KCPE-KCSE



00Chemistry paper 1, 2&3 MAKUENI COUNTY CLUSTER PREPARATORY EXAMINATION 2016 233/1 CHEMISTRY PAPER 1 (THEORY) JULY/AUGUST 2016 TIME: 2 HOURS.1.2.3.4.5.6.The following represents a Bunsen Burner flame.AB(a) Name the parts of the flame labeled A and B.(b) Identify the hottest part of the flame. Give a reason.Give the I.U.P.A.C name of the oxide of nitrogen that:-(i) Relights a glowing splint(ii) Forms brown complex compound with acidified Iron (II) sulphate solution(iii) Reacts with water to form nitric (V) acidThe table below shows PH values of substances A, B, C and D. Study it and answer the questions that follow. Substance A B C DPH31017(a) Which substance is likely to be pure water(b) Which solution contains the lowest concentration of hydrogen ions?(c) In the equation below, identify the reagent that acts as a base. Give a reason for your answer.H2O2(aq) + H2O(l)H3O+(aq) + H- (aq)Identify the particles which enable the following substances to conduct electricity. (i) Aluminium metal(ii) Molten lead (II) bromideElement R - 238 decays in series forming different nuclides as shown below.RXP YT(a) Identify the type of decay X and Y(b) Give one use of radioactive isotopes in medicineA form two student in an attempt to prevent rusting, put copper and zinc in contact with iron as shown below.Iron(2 marks)(1 mark)(1 mark) (1 mark) (1 mark)(? mark) (? mark) (2 marks)(1 mark)(2 marks) (1 mark) XYIronCopperZinc(i) State what would happen in set up X and Y after one week.(2 marks)(ii) Explain your answer in diagram Y.(1mark)7.Study the table below and answer the questions that follow.IonX3+Y2-Electron arrangement2,82,8,8(a) Write the electronic arrangement of elements. X and Y (b) Write the formula of the compound that would be formed between X and Y. 8. Study the flowchart below and answer the questions that follow. Colourless gas Solid NBrown gasMetal oxide LPage | 100Chemistry paper 1, 2&3 (a)Write the formula of the anion present in solid N.(1 mark)(b)Solid N in the flow chart above burns in air with a red flame. Identify the(i) Cation present in solid N(1mark)(ii) Metal oxide L9.Study the information in the table below and answer the question the table below the table.BondBond energy (kJmol-1)C-H414Cl-Cl244C-Cl326H-Cl431Calculate the enthalpy change for the reactor.(3marks)CH4 (g) + Cl2 (g) → CH3Cl(g) + HCl(g)10.The table below shows the tests carried out on separate samples of water drawn from a well and the results obtained.TestResults(i) Addition of excess aqueous ammoniaWhite precipitate(ii) Addition of a few drops of dilute sulphuric (VI) acidNo observable change(iii) Addition of dilute hydrochloric acid followed by a few drops of Barium ChlorideWhite precipitate(a) Identify the cation and the anion present in the water.(1 mark)(b) Write an ionic equation for the reaction which takes place in test (iii)(1 mark)11.Study the structure below.C3H7COOC2H5(a) Name the compound(1 mark)(b) Name the compounds used to prepare the above compound.(1mark)(c) What is the identifying physical property of the above compound?12.Study the information in the table and answer the questions below.SubstanceSolubility g/100g waterV126W2Describe how a solid sample of substance V could be obtained from solid mixture of V and W.(3 marks)13.In order to prepare hydrogen gas in the laboratory a student set-up the apparatus shown in the diagram below. Study it andanswer the questions that follow.Dropping funnelConc. Nitric (V) acidDeliveryGas jartubeTroughWaterAluminium(a)Suggest why the student did not collect hydrogen gas.(b)In a separate experiment the student reacted iron and hydrochloric acid to prepare hydrogen gas.(i) Write an ionic equation for the reaction.(1mark)(ii) The hydrogen gas produced was found to have a foul smell. Suggest an explanation for this.(1mark)14.In an experiment, excess magnesium ribbons were immersed in ethanoic acid and the gas evolved was measured at 10seconds intervals.(a)Write an equation for the reaction between Ethanoic acid and magnesium ribbon.(1mark)(b)Sketch a curve of volume of gas evolved against time for the above reaction.Time in secondsPage | 200Chemistry paper 1, 2&3 (c) On the same axis above sketch the curve that would be obtained of hydrochloric acid was used. Label the curve 1. (1 mark) 15.When excess chlorine is bubbled through cold dilute sodium hydroxide solution, the resulting solution is a bleaching agent.(a) Write a chemical equation for the reaction that produces the bleaching agent.(1 mark)(b) Name the bleaching compound and show how it bleaches using an equation.(2 marks)16.An element X has a relative atomic mass of 88. When a current of 0.5 amphere was passed through a fused chloride of X for32 minutes 10 seconds, 0.44g of X was deposited.(i) Determine the charge of element X (1 Faraday = 96500C)(2 marks)(ii) Write the formula of hydroxide of X.(1 mark)17.(a) Name two ores from which zinc is extracted.(1 mark)(b) During extraction of zinc metal, the ore is subjected to froth floatation. Give a reason why this process is necessary.(1 mark)(c) Name one alloy of zinc and state its use.18.(a) State Graham?s law of diffusion.(b) Two gases A and B have relative densities of 1.98 and 2.90 respectively. They diffuse under the same conditions.(i) Compare their rates of diffusion(1 mark)(ii) Determine the relative molecular mass of A, given that the relative molecular mass of B is 64.(2 marks)19.The table below shows elements in the halogen group of the periodic table. Study the table and answer the questions thatfollow.ElementAtomic numberMelting point 0CFluorine9-218Chlorine17-101Bromine35-7Iodine53114(i) Name the element likely to be a solid at room temperature. Explain(1 mark)(ii) Explain why the melting point increases from fluorine to iodine.(2 marks)20.Starting with aluminium sulphate, describe how a solid sample of aluminium hydroxide could be prepared.(2 Marks)21.Study the following flow chart and answer the questions that follow.Process THCl(g)Alcohol R(i) Write the formula ofI. Alcohol RII. Compound S(ii) Name process TConc. H2SO4(l)EthaneCompound S(1 mark)(1 mark)(1 mark) 22.The table below gives atomic numbers of elements represented by the letters A, B, C and D.ElementABCDAtomic number15161720Use the information to answer the questions that follow.(a)Name the type of bonding that exists in the compound formed when A and D react.(1 mark)(b)Select the letter which represents the best oxidizing agent. Give a reason for your answer.(1 mark)(c)Give a reason why phosphorous is stored under water.(1 mark)23.Production of hydrogen iodide can be demonstrated by the equation.H2(g) + I2(g)2HI(g)Energy KJ/mole2HI(g)H2(g) + I2(g) Reaction pathExplain how the following would affect the yield of hydrogen iodide.(i) Increase in temperature(2 marks)(ii) Decrease in pressure(1 mark)Page | 300Chemistry paper 1, 2&3 24. Use the scheme below to answer the questions that follow. Carbon (IV) Oxide Solid HHeatH2OSolid JCa(OH)2(aq)(a) Identify the solids; S and J(2 marks)(b) State one commercial use of solid J.(1 mark)Given the equations, determine the heat of formation of ethanol.(3 marks)C(s) + O2(g)CO2(g)?H = -393Kj/molH2(g) + O2(g)H2O(l)?H = -286Kj/molC2H5OH (l) + 3O2(g)2CO2(g) + 3H2O(l)?H = -1368kJ/molExplain how you would separate a mixture of ammonium chloride and sodium chloride into its pure components.(2 marks)25.Natural Gallium consists of two isotopes 68Ga and 71Ga in the ratio 3:2 respectively. Given that the atomic number ofgallium is 31.(a) Calculate the number of neutrons in the isotope 68Ga.(? mark)Calculate the relative atomic mass of gallium(1? mark)A piece of burning magnesium was lowered into a gas jar of Carbon (IV) oxide.(b) State the observations made.(2 marks)Write an equation for the reaction in (a) above.(1 mark)Page | 400Chemistry paper 1, 2&3 MAKUENI COUNTY CLUSTER PREPARATORY EXAMINATION 2016 233/2 CHEMISTRY PAPER 2 (THEORY) JULY/AUGUST 2016 TIME: 2 HOURS. 1.(a) The grid below is part of the periodic table. Letters are not actual symbols. Study it and answer thequestions that follow.GIKLHJMN(i) Give the letters representing atoms that can form a singly-charged anion.(1 mark)(ii) Identify the most electromagnetic element in the grid. Explain.(1 mark)(iii) Identify the strongest reducing agent.(1 mark)(iv) Write the formula of the most stable compound formed when J and K react(1 mark)(v) Give the name of the type of bond in the compound formed in (iv) above.(? mark)(vi) Give the chemical family name of L and M.(? mark)(viii) Write the ionic equation for the reaction in which gas L is bubbled through a solution with ions of M.(1mark)(ix) Element P is alkaline earth metal and belongs to period 2. Indicate its position on the grid.(1 mark)(b) Use the information in the table below to answer the questions that follow.ElementAtomic numberMelting point 0CQ1198R12650S141410T17-102U18-189V1964Give a reason why the melting point of:(i) Q is higher than of V.(1 mark)(ii) R is higher than of Q.(1 mark)(iii) S is the highest.(1 mark)2. (a) A form one student crushed banana leaves with water and left the mixture for some days. He found that the mixture had fermented. He suspected that the mixture had been contaminated with ethanol which has a boiling point of 78 0C while water has a boiling point of 1000C. The student then set up the apparatus below to separate the mixture. Thermometer ADB C Distillate Heat (i) Name the piece of apparatus labelled B.(1 mark)(ii) What is the purpose of the thermometer in the set up?(1 mark)(iii) At what point of apparatus B should the tap water be connected. Explain.(2 marks)Page | 500Chemistry paper 1, 2&3 (iv) Name the part labelled A and state its function(2 marks)(v) Which liquid was collected first? Explain(1 mark)(vi) What is the name given to the above method of separating mixtures?(1 mark)(vii) What property of the components of the mixture makes it possible for the components to be separated by the method?(1mark)(viii) State two applications of the above method of separation.(b) A form two student was supplied with a liquid suspected to be water. (i) Describe one chemical test that would be carried out to show that the liquid was water. (ii) How would it have been proved that the liquid is pure water?3.The flow chart shows some chemical reactions.NaOHCH3COOHStep ICH3COOHEthanolNaE(2 marks)(1 mark)CH3COONaCompound ACH3CH2OHH2SO(4)(l)CH4Cl2 Step IIBr(g)DH2CCH2=CH2FStep IIICH2 = CH2(X)n (a)Draw the structural formula and names of the following compounds.(3 marks)CompoundNameStructure formulaA C D (b)Write the name of the processes that leads to the formation of substances A and F.(1marks)SubstanceProcessA F (c)Name the type of reaction and conditions required for the formation Step 1(1 mark)(d)If the relative molecular mass of compound X is 84000 units, determine the value of n (C = 12, H = 1)(1 mark)(e)Write an equation that leads to the formation of substance E.(1 mark)(f)State and explain the observation made when substances F and CH2=CH2 are burnt in excess air.(2 marks)(g)Given the thermochemical equations for combustion of ethanol, hydrogen and graphite (carbon)C2H5OH(aq) + 3O2(g)2CO2(g) + 3H2O4(l)?H = -1368kJ/molH2(g) + O2(g)H2O(l)? H = -286 kJ/molC(s) + O2(g)CO2(g)? H = -393 kJ/mol(i) Draw an energy cycle diagram to represent the above information linking the formation of ethanol with its enthalpy ofcombustion and its constituents.(2 marks)(ii) Calculate the enthalpy of formation of ethanol(2 marks)4.In an experiment to study the rate of reaction between duralumin (an alloy of aluminium, magnesium and copper) andhydrochloric acid, 0.5g of the alloy were reacted with excess 4M hydrochloric acid. The data in the table below was recorded.Use it to answer the questions that follow.Time (minutes)0.01.02.03.04.05.06.07.0Vol of gas evolved, cm30.0220.0410.0540.0620.0640.0640.0640.0(a)(i) Plot a graph of total volume of gas produced against time.(3 marks)(ii) From the graph, determine the volume of the gas produced at the end of the 2 ? minutes.(1 mark)(b)Determine the rate of reaction between the 3rd and 4th minute.(1 mark)(c)Give a reason why some solid remained at the end of the experiment.(2 mark)(d)Given that 2.5cm3 of the total volume of gas was from the reaction between magnesium andPage | 600Chemistry paper 1, 2&3 hydrochloric acid. Calculate the percentage by mass of aluminium present in 0.5g of the alloy.(Al = 27, Molar gas volume = 24000cm3)5.The chart shows the extraction of lead from its ore.Galena ore +ImpuritiesSubstance ALimestonePowdered oreCokeRoasting furnaceSmelting furnaceGas Y(3 marks)Molten Lead Substance Z Substance B(a)Write the chemical formula of the chief ore.(1 mark)(b)Name the possible impurities present in the ore.(2 marks)(c)Why is it necessary for the ore to be converted into powder form?(1 mark)(d)Identify process X and state it?s significance(1 mark)(e)Write equations for the reaction taking place in theI. Roasting furnace(1 mark)II. Formation of substance B(1 mark)It is not advisable to use lead pipes in transporting drinking water.(1 mark)(f)Identify one of the impurities present in molten lead obtained by the process.(1 mark)(g)State one use of lead(1 mark)6.(a) Study the standard electrode potentials below and answer the questions that follow. The letters do not represent the actualsymbols of the elements.E? voltsE2+(aq) + 2e-E(s)-0.44A+(aq) + e-A(s)-2.92?D2(s) + e-D-(aq)+1.36C+(aq) + e-? C2(g)0.00B+(aq) + e-B (s)+0.52(i) Identify the strongest reducing agent. Give a reason.(1 mark)(ii) Select two half cells when combined produce the highest potential difference and determine the electromotive force.(2 marks)(iii) Which element is likely to be hydrogen? Give a reason(2 marks)(iv) Explain whether the reaction represented below can take place.(2 marks)2A+(aq) + E(s)→ 2A(s) + E2+ (aq)(b) The apparatus below shows the set up that was used in the electrolysis of 2M Sulphuric (VI) acid. Study it and answer the questions that follow. Battery Gas FGas G2M Sulphuric (VI) Acid (i) Write an equation for the reaction that produce gas F.(1 mark)(ii) Describe how gas G can be identified(1 mark)(iii) Why is the concentration of the acid expected to increase during electrolysis.(2 marks)Page | 7Chemistry paper 1, 2&3 7.The following results were obtained in an experiment to determine the heat of neutralization of 50cm3 2M hydrochloric acidand 50cm3 2M sodium hydroxide.Mass of plastic cup=45.1gInitial temperature of acid=27.00CInitial temperature of alkali=23.00CMass of plastic cup + HCl + NaOH=145.1gTemperature of the mixture of acid and alkali=38.50C(a) Define heat of neutralization(1 mark)(b) Write an ionic equation for the neutralization of hydrochloric acid and sodium hydroxide.(1 mark)(i) The amount of heat produced during the experiment(2 marks)(Specific heat capacity of solution = 4.2jg-1k-1, density of solution = 1gcm3) (ii) Molar heat of neutralization for the reaction.(2? marks)(c) Explain why the molar heat of neutralization of NaOH and Ethanoic acid of equal volume and molarity would be less than thevalue obtained in C (ii) above.(1 mark)(d) Write down the thermochemical equation for reaction between NaOH and dilute hydrochloric acidabove(1 mark)(e) Draw an energy level diagram for the neutralization reaction in (e) above.(2 marks)Page | 8Chemistry paper 1, 2&3 MAKUENI COUNTY CLUSTER PREPARATORY EXAMINATION 2016 CHEMISTRY 233/3 CONFIDENTIAL Requirement; In addition to the apparatus and fittings found in a chemistry laboratory each candidate will require the following: ?Solid P (1.8g of oxalic acid) in a stoppered container.?Solution Q - 100cm3?Pipette and pipette filler.?100 cm3 measuring cylinder.?250cm3 beakers (two)?250cm3 volumetric flasks.?1 label?Burette?One boiling tube?Five dry clean test tubes in a rack?Clamp stand?Solution L - 50cm3?Stop watch?10cm3 measuring cylinder (2)?Tripod stand and wire gauze?Thermometer (-10oC - 110oC)?Test tube holder?Funnel?250 cm3 conical flasks ( 2)?Test tube holders?Distilled water?White tile?Solid D - 2g Lead II Nitrate in a stoppered container.?Solid M - 2g Sodium Chloride in a stoppered container.?Solid T - 2g Malleic Acid in a stoppered container.?Solid Sodium Hydrogen Carbonate in a stoppered container.Access to:-?2M Sodium Hydroxide supplied with a dropper.?2M Ammonium Hydroxide with a dropper.?0.05M Potassium Iodide solution with a dropper.?Acidified Potassium Dichromate (VI) with a dropper.?Acidified potassium manganate (VII) supplied with a dropper.?Phenolphthalein indicator supplied with a dropper.?Bunsen burner.Notes:1.Solution Q is prepared by dissolving 4g of sodium hydroxide in distilled water and diluting to one litre.2.Solution L is prepared by dissolving 3.16g of potassium manganate (VII) in 200cm3 of 2MH2S04 and adding water to makeup to one litre.3.Acidified potassium dichromate (VI) is prepared by dissolving 29.4g in 400cm3 of 2MH2S04 and adding water to make up toone litre.Page | 9Chemistry paper 1, 2&3 MAKUENI COUNTY CLUSTER PREPARATORY EXAMINATION 2016 233/3 CHEMISTRY Paper 3 Practical July/ August 2016. Time: 2 ? Hours 1.You are provided with:-1.8g of dibasic acid H2X labeled solid P.-Solution Q containing 1.0g of sodium hydroxide in 250 cm3 of the solution.-Phenolphthalein indicator.You are required to:-Prepare 250.0cm3 of solution using solid P.-Determine the value of X in the formula H2XProcedure: Place all solid P in 250cm3 beaker. Add about 100cm3 of distilled water to the beaker. Swirl until all the solid dissolves. Transfer the solution into a 250cm3 volumetric flask. Top up with distilled water to the mark and label it solution P. Using a measuring cylinder transfer about 100cm3 of the solution P into a 250cm3 beaker, preserve the rest in the volumetric flask for procedure II. Pipette 25cm3 of solution Q into a clean conical flask. Add 2- 3 drops of phenolphthalein indicator to the 25 cm3 solution in the conical flask. Fill the burette with solution P from the beaker. Titrate until the pink colour disappears. Repeat two more times and record the results in the table below. Table1. 123Final burette reading Initial burette reading Volume of solution P used (cm3) (4 marks) a)Calculate the average volume of solution P used.(1 mark)b)Calculate the molarity of solution Q (Na = 23.0, O = 16.0, H = 1.0).( 2 mark)c)How many moles of sodium hydroxide were pipette.(1 mark)d)How many moles of the acid, solution P reacted with 25.0 cm3 of solution Q.(2 marks)e)How many moles of H2X were present in 1.8g of solid P.(2 marks)f)Determine the value of X in the formula H2X (H = 1)(2 marks)B) Procedure IIYou are provided with:--Acidified potassium manganate VII, solution L.-Solution P dibasic acid H2X-A stop watch / clock.-Thermometer.You are required to determine how the rate of reaction of potassium manganate VII, solution L with the dibasic acid, solution P varies with change in temperature. Using a 10cm3 measuring cylinder, place 2.0cm3 of solution L portions into FIVE test tubes on a test tube rack. Clean the measuring cylinder and use it to place 10.0cm3 of solution P into a boiling tube. Prepare a water bath by placing about 200cm3 of water in beaker and start heating it. Insert a thermometer in solution P in the boiling tube and place the boiling tube in the warm water bath till the solution P attains temperature of 400C. Remove the boiling tube from the water bath and add the first portion of solution and the same time start a stop watch. Record the time taken for the purple colour of the mixture to decolourise in table II below. Repeat the experiment by using 10.0cm3 of solution P at temperature on 500C, 600C, 700C and 800C. Record the times in table II. Complete the table by computing a) Table II Temperature of solution. Time for colour to decolourise (sec) (5 marks) b) Plot a graph of( y axis) against temperature(3 marks)Page | 10Chemistry paper 1, 2&3 c) From the graph determine the time taken to decolourise the mixture if the mixture is at a temperature of 650C. (2 Marks) d) How does the rate of reaction of potassium manganate (VII) with oxalic acid vary with temperature?(1 mark)2.You are provided with solid D, carry out the tests below. Write your observations and inferences in the spaces provided.a)Using a boiling tube, dissolve all solid D in about 20cm3 distilled water, label this as solution D. Divide the solutionobtained into three portions of about 2cm3. Retain the remaining solution for use in question 2 a. (iv).i)To the first portion add aqueous sodium hydroxide dropwise until in excess.ObservationInferences(1mark)( 1mark)ii)To the second portion add aqueous ammonium hydroxide dropwise until in excess.ObservationInferences(1mark)( 1mark)iii)To the third portion add a few drops of potassium iodide.ObservationInferences( ? mark)( ? mark)iv)Using a clean boiling tube dissolve all solid M in about 10cm3 distilled water. To about 2cm3 of solution, add few dropsof solution D. Heat the contents of the test tube strongly.ObservationInferences(1mark)( 1mark)b)You are provided with solid T. carry out the tests below. Write your observations and inferences in the spaces provided.i)Place about one third of solid T on a metallic spatula and burn it using a Bunsen burner.ObservationInferences(1mark)( 1mark)ii)Place the remaining of solid T in a test tube. Add about 6cm3 of distilled water and shake the mixture well. (retain themixture for use in test C)ObservationInferences(1mark)( 1mark)c)i)To about 2cm3 of the mixture, add a small amount of solid sodium hydrogen carbonate.ObservationInferences(1mark)( 1mark)ii)To about 1 cm3 of the mixture add 1.0cm3 of acidified potassium chromate (VI) and warm.ObservationInferences(1mark)( 1mark)iii)To about 2cm3 of the mixture add two drops of acidified potassium manganate (VII).ObservationInferences(1mark)( 1mark)Page | 11Chemistry paper 1, 2&3 MAKUENI COUNTY CLUSTER PREPARATORY EXAMINATION 2016 Kenya Certificate of Secondary Education (K.C.S.E) CHEMISTRY Paper 1 Marking scheme 1.a)A - Pale blue zone.1 markB - Green blue zone.1 markb)A reason; ? ? complete combustion takes place due to plenty of air. ? ?Total 3 marks2.i)Nitrogen (I) oxide?ii)Nitrogen (II) oxide?iii)Nitrogen (IV) oxide?3marks3.a)Substance D ? ?b)Substance A ? ?c)H2O2 (hydrogen peroxide) is the base. ? 1Reason: It is a proton donor. ? 14.a)Aluminium metal - delocalized electrons. ? 1b)Molten lead II (bromide) - mobile ions. ?Accept Pb2+ and Br- ions 5.i)X - α? 1Y - β? 1 ii)-Treat cancer? 1-Dating? 1 -Detecting leakage in water pipes. ? 1 -Sterilization of hospital equipment for surgery? 1 -Energy? 1 NB: accept specific uses 6.i)X - Iron rustedY - No rusting on iron.ii)Zinc more reactive than iron hence zinc undergoes corrosion in place of iron. i.e. zinc reacts with oxygen and moisture.W.T.T.E7.a)X - 2.8.3 ? 1Y - 2.8.6 ? 1b)X2Y3? 18.a)b)i) Ca2+?ii) CaO or LO??9.Bond breaking? (414 x 4) + 244 = 1900kJ? 1 Bonding formation ? - 326 + (- 414 x3) + (- 431) = 1999kJ ? 1 Energy change = bond breaking - bond formation. = 1900 - 1999? ? = - 99kJ? ? 10. a) Cation : Al3+ Anion: b) Ba 2+ (aq) + SO4 2-(aq)→ BaSO4 (s)11. a) Ethylbutanoate ? 1b) Butanoic acid and ethanol ?1c) Fruity / pleasant smell. ? 1(Reject sweet smell)12.-Add water to the solid mixture.-V dissolves while W will not-Filter to obtain W as residue-Heat the filtrate to evaporate the water13. a) conc. HNO3 is a strong oxidizing agent. It oxidizes and thickens the thin coating of aluminium oxide thus leading to no reaction between metal and acid. ?1 b) Fe(s) + 2H+ (aq) → Fe2+ + H2 (g) ? 1 c) Sulphide impurities in the iron react with the acid to form hydrogen sulphide gas which has foul smell. ? 1 14. a)2CH3 COOH (aq) + Mg (s) → (CH3 COO)2 Mg (aq) + H2 (g) ? 1b) and c)Page | 1200Chemistry paper 1, 2&3 I Curve I ? ? mark Second curve ? ? mark Flattening correctly ? mark Time in seconds 15. a) 2NaOH (aq) + Cl2 (g) → NaOCl (aq) + NaCl (aq) + H2O (l) ? 1 b) Bleaching compound - Sodium chlorite (l) ? 1 NaOCl (aq) + dye → NaCl (aq) + colourless ? 1 16.T = (32 x60) + 10 = 1930s ? 1I = 0.5 Q = It = 0.5 x 1930 = 765 C 0.44 - 965C 88g?x 96,500 = 19,3000C ? 1 Charge of X == 2:. X(OH)2 17. a) Calamine? ? Zinc blende? ? b) Increase concentration ? ? of the metal ore by reducing the impurities. ? ? c) Alloy - Bronze? ? Use - in making of trophies for awards in games, ? ? 18. a) Under the same conditions of temperature and pressure, the rate of diffusion of a gas is inversely proportional to the square root of its density. (1mark) b) i)= √? ?= 1.21Gas B diffuses 1.21 times faster than A. ? ?ii)= √or= √?== R.MMA =? ?= 43.6965? ?19. a) Iodine ? ? melting point above r.t.p ? ?b) Molecular mass increases, thus increasing intermolecular forces of attraction. ? 120.-Put the aluminium sulphate in a beaker-? ?Add aqueous ammonia dropwise until in excess-? ?Filter the mixture-? ?Dry the residue? ? in a desicator at low temperatures to obtain solid aluminium hydroxide.21. (i) I : Ethanol? 1II: Chloroethane? 1(ii) Dehydration. ? 1Page | 13Chemistry paper 1, 2&3 22. a) ionic or electrovalent bonding. ? 1 b) Element C? ? Reason: it has seven (7) electrons in the outermost energy level and hence easily gains an electron to complete the octet? ? c) To keep away air or oxygen which would react with it. ? 1 23. a) Forward reaction favoured since reaction is endothermic ; more HI produced? 1 b) Reactant side 2V products side 2V volumes are the same therefore pressure has no effect. ? 1 24. a) H:Calcium carbonate ? 1J:Calcium oxide ? 1b) J:Is used as a drying agent. ? 125. 2C(s) +3H2(g) + ? O2(g)C2H5OH(l)?Hf = ? Energy cycle ? 1 +2O2(g)+ O2(g)+ 3O2(g)?H= 2(-393) ? ? ?H= 3(-286) ? ? ?H= - 1368kJ? ? 2CO2(g) + 3H2O(l)?Hf= -786 + - 858 + 1368? ?= - 276 kJ/Mol? ?26.-Heat the mixture. ? 1-Ammonium chloride sublimes? 1-Sodium chloride does not sublime.27. a)68 - 31 = 37 neutrons? ?)()b) R.A.M = (? ?()=? ?= 69.2 ? ?28. a) black specks ? 1White powder ? 1b)2 Mg (s) + CO2 (g) → 2 MgO (s) + C (s) ? 1Page | 14Chemistry paper 1, 2&3 MAKUENI COUNTY CLUSTER PREPARATORY EXAMINATION 2016 CHEMISTRY PAPER 233/2 PAPER 2 MARKING SCHEME 1.(a)(i) L and M ? 1(ii) L ? 1 Non - metal with the smallest atomic ? ? 1 size hence the highest electron affinity. ? ? (iii) H ? 1 (iv) J2k3 ? 1 (v) Ionic/electrovalent ? 1 (vi) Halogens ? 1 (Reject group seven element) (vii) L2(g) + 2M-(aq)?2L-(aq) + M2(g)(viii)I: Both are metals ? 1II. N is a noble gas hence inert. (Accept: N has stable electronic configuration) (ix) Position G? 1P H (b) (i) V has a larger atomic size ? ?, hence metallic bond is weaker. (ii) R has more protons hence greater ? ? nuclear charge making the metallic bond stronger ? (iii) Giant atomic structure. ? ? 2. (a) (i) Liebig condenser ? 1 (ii) It helps in determining ? 1 the boiling range so that pure ethanol is obtained. When liquids boil, there temperatures remain constant. (iii) Point C; ? 1 Explanation: The cold water will provide maximum contact with the distillate in the delivery tube. ? 1 (iv) Part A: Fractionating column. ? 1 ? It increases the surface area for condensation of the substance whose boiling point has not been reached. ? ? ? Provides a surface in which vapour condenses into liquid and the liquid redistills. ? ? (v) ? Ethanol was collected first ? ? ? It has a lower boiling point 780C, hence it boils first. ? ? (vi) Fractional distillation ? 1 (vii) Have different but close boiling points. ? 1 (viii) ? Manufacture of spirits ? Fractional distillation of crude oil. ? Obtaining oxygen from liquid air. (Any two which are correct 2 marks) (b) (i) Add to any drous cobalt chloride paper which turn from blue to pink. ? 1 OR: Add the liquid to anhydrous copper (II) sulphate which turns from white to blue. ? 1 (Any correct one for 1 mk) (ii) By determining the boiling point of the liquid. ? 13.(a) A - Ethyl ethanoate ??H O H H|||||CH3COOHCH2CH3/ H-C- C-O-C-C-H ??|||HH HC | C = dichloromethane?? CH2Cl2/ H - Cl | H H H ||D - 1,2 - dibromoe ethane ?? CH2BrCH2Br// H - C- C - Br ??||Br H (b) A - Esterification ? ? B - Hydrogenation ? ? (c) Type of reaction:- Oxidation ? ? Page | 1500Chemistry paper 1, 2&3 Conditions: Acidified potassium manganate or acidified potassium dichromate (VI) (Reject: Formulae without H+(aq) to show acidification.) (d)(CH2CH2)n = 84,00028n = 84,000n =? ?n = 3000 ? ?(e) Equation. 2CH3CH2OH (aq) + 2Na(s) ?2CH3CH2ONa(aq) + H2 (g) ? 1(f)- CH2CH2; Burns with a very sooty flame ? ?- Reason has a double bond hence unsaturated. ? ? - F; Burns with a blue flame/less sooty flame ? ? - Reason: Has C-C single bond hence ? ? saturated. (g) (i) Energy circle.2C(s) + 3H2(g) + O2? Hf? ?C2H5OH(l)?H3 O2 ? ?32O2?H2? ? 3O2?H1 ? ? 2CO2(g)+3H2O(l)(Correctly drawn maximum 2 mks) (ii) Enthalpy of formation of ethanol. ? Hf + ? H1 = ? H2 + ?H3 ? ? ?Hf = ? H2 + ?H3 ? Hf = 3 (-286 ) + 2(-393) ? ? - 3(-1368) = -858 - 786 + 1368 = -276kJ mol-1 ? ? (If units missing penalize ? mark)4.(a) (i) Graph scan(ii) 490?10cm3 ? 1 (Mark shown on the graph)Page | 16Chemistry paper 1, 2&3 (b)? ? = 80cm3/min ? 1(c) Copper ? 1 which is part of duralumin does not react with the acid. ? 1(d) Volume of gas released from Al reacting = 640 - 2.5 = 638.75cm3 ?Moles of H2(g);moles ? ?Moles of Al;= 0.01774 moles ? ?Moles of Al; 27 x 0.01774 = 0.47906g% of Al by mass =x 100 = 95.8125%5.(a) Chief ore formula PbS ? 1(b) Possible impurities ? Zinc sulphide (ZnS) ? 1 ? Silicon oxide ? 1 (Accept - sand) (c) It is converted to powder form ? 1 to increase the surface area of the ore and expose the mineral. (d) Process X is - froth floatation ? 1 significance: Concentrates the ore. (e) Equations I. 2PbS(s) + 3O2(g) ?2PbO(s) + 2SO2(g)(Penalize fully if not balanced, penalize ? mark for wrong state symbols) (II) PbS(s) + Fe(s) ? FeS(s) + Pb(s) ? 1 (f) Dissolved lead will cause brain damage when taken in our bodies. ? 1 (g) Impurities in molten lead ? Silver ? Gold ? Copper? 1 (Any for 1 mk)? Tin ? Sulphur ? Arsenic compounds (h) ? Used in radioactive shielding ? Used in manufacture of lead acid accumulators. ? Used for making paint. ? Used making bullets. ? Used in manufacture of soldering wire ? Used in making lead pipes and ball bearings. ? Tetraethyl is added to petrol as an antiknock additive.(Any one correct use ? 1)6.(a) (i) Strongest reducing agent;Reason; Has the most negative E? value ? ? (ii) A? ? and D2 or D ? ? NB: The two must be correct. E.M.F = 1.36 - - 1 2.92 ? ? = + 4.28V ? ? (iii) C ? 1 Reason: Has E? value of 0.00V ? ? and has been used as reference electrode? ? (iv) E(s) ? E2+ (aq) + 2e-E? = +0.44V ? ?2E- + 2A+(aq)? 2A(s)E? = -2.92V? ?Summing up.E(s) + 2A+(aq)?2A(s) + E2+(aq)E? = -2.48VIt cannot take place since E? = -2.48V(b)(i) Equation for producing gas F.4OH-(aq)? 4e- + 2H2O(l) + O2(g) ? 1(ii) - Introduce a burning splint at the mouth of the test tube ? ? - A pop sound is produced ? ? (iii) - H+(aq) and OH-(aq) are discharged ? 1 or water is electrolysed/decomposed. - The amount of water electrolysed is more than the amount of water formed at the anode. ? 1 7. (a) Heat of Neutralization is the enthalpy change when 1 mole of hydrogen ions from an acid react with 1 mole of ions from an alkali/base to form one mole of water. (b) H+(aq) + OH-(aq) ? H2O(l) ? 1 (c) (i) Temperature change = 38.5 - () ? ?= 25.00CMass of the solution = 145.1 - 45.1? ?= 100g(ii) Moles of NaOH reacting1000cm3 ? 2 moles50cm3 =x 2 = 0.1 moleLikewise: Mole of HCl reacting ? ?1000cm3 ? 2 molesPage | 1700Chemistry paper 1, 2&3 50cm3 =x 2 = 0.1 moleMole ratio NaOH ? 1:1 respectively. ? ? ? If 0.1 mole ? 5.67 kJoules ? ? 1 mole == -56.7kJmol-1? ?(If units or sign missing penalise ? mark)(d) Some of the energy ? ? is used to ionize the weak Ethanoic acid. ? 1 (e) Equation: NaOH(aq) + HCl(aq)? NaCl(aq) + H2O(l) ? 1(f) NaOH(aq) + HCl(aq) ? ? ? H = -56.7kJ/molEnthalpyOR/Energy ? ?NaCl(aq) + H2O(l) ? ?Reaction path (Progress) ? ? Page | 18Chemistry paper 1, 2&3 MAKUENI COUNTY CLUSTER PREPARATORY EXAMINATION 2016 Kenya Certificate of Secondary Education (K.C.S.E.) Chemistry 3 Practical Time: 2 ? Hours MARKING SCHEME TABLE 1 1.Procedure 1Final burette reading21.543.021.5Initial burette reading0.021.50.0Volume of solution P used ( cm 3)21.521.521.5Table 1 ………………..5marksAward a total of 5 marks distributed as follows:-a)Complete table ……………………………….…..1 marki)Complete table with 3 titration done ………...1 markii) Incomplete table with 2 titration done …...….? markiii) Incomplete table with only 1 titration done ...0 marksb)Use of decimals ( tied to 1st and 2nd rows only )1 marki)Accept either one or two decimal places used consistently, otherwise penalize fully.ii) If 2 decimal places are used, the second decimal place must be a “0” or “5”,otherwise penalize fully.iii) Accept inconsistency in the use of zeros as initial burette reading. i.e 0, 0.0, 0.00.c)Accuracy………………………………………. 1 markCompare the candidate?s titre value with the school value (v.s), tick the chosen value where it earns accredit.Conditionsi)If at least one value is within0.1 cm3 of school value …….1 markii) If no value is within0.1 of s.v but at least one within0.2 cm3 of v.s …….. ? markiii) If no value is within0.2 cm3 of s.v ………………0 markd)PRINCIPLES OF AVERAGING. ………………………………….. 1markValues averaged must be shown and must be within0.2 cm3 of each other.Conditions i) If 3 consistent values averaged ………………………………1mark ii) If 3 titrations are done but only 2 are consistent and averaged …. 1mark iii) If only 2 titrations are done, are consistent and averaged ………..1 mark iv) If only 3 values are possible but only 2 are averaged ……0 mark. v) If only 2 titrations are done ,are inconsistent and averaged ….0 mark vi) If 3 titrations are done, are inconsistent and yet averaged …..0 mark e)FINAL ANSWER ……………………………..1 markCompare the candidates correct AVERAGE TITRE with s.v.i)If it is within0.2cm3 of v.s …………..0markii) If it is not withincm3 of v.s but it is within0.2 cm3 of v.s …….. ? marks.iii) If it is beyondcm3 of v.s ……….. 0marks.CALCULATIONSb)Molarity of solution Q ………… 1markx1 ? mk= o.1M NaOH ? mk….c)Moles of sodium hydroxide pipetted ….1mk?= 0.0025 moles ? mkd)Moles of acid, solution P that reacted with 25.0 cm3 of solution Q ……….. 2mksEquationH2X (aq) + 2 NaOH (aq) → Na2X (aq) + 2H2O(l) ……..1mk ? mk = 0.00125 moles ? mk e) Moles of H2X in 1.8g of solid P ………………….1 mk 1 ? mk Page | 19Chemistry paper 1, 2&3 f) RMM of H2X …………………………….2mk ? mk g)- 2? mk= correct answer ….. ? mkB.PROCEDURE.a)Table II ……………………………. (5marks)Temperature of solution400C500C600C700C800CTime for colour to decolourise (sec)77331252sec -10.0130.0300.0830.20.5Award a total of 5mks distributed as follows:-COMPLETE TABLE (tied to second row)…….1mk Complete table with 5 readings …………1mk Incomplete table with 4 readings ……….1mk Incomplete table with 3 readings ………. ? mk Incomplete table with 1 -2 readings ……….0mk Use of decimals (tied to 2nd row) ………. (1 mark) Conditions: i)Accept time reading and award 1mk ONLY IF CONSISTENTLY given as a whole numbers or to 1 decimalplace, otherwise penalize fully.ii)Reject and award 0 mk if decimal place other values other than “0” or “5” e.g. 77.3 or 33.9.ACCURACY (tied to 2nd row) …….. (1mk)Compare school values (s.v) to candidates reading at temperature = 400C and award 1 mk if the reading is within seconds of the s.v. NB: S.V refers to teachers time reading at temp = 400C TREND: ( Tied to 2nd row) ……. (1mark) Award 1mk for continuous drop in time (sec) ,otherwise penalize fully. ROW 3 (1mk) -Award 1 mk for 5 calculated and correct values.-Award ? for 4 calculated values otherwise penalize fully for values between 3 and 1.b)Graph …………………………………. (3 mk)Award a total of 3mks distributed as follows.LABELING OF AXIS ……………………… ? mkAward ? mk only if both axes are correctly labeled (i.esec on the vertical axis) and Temperature on horizontal axes.SCALE ………………………….. ? mkConditionsi)Area covered by plots should be at least half the grid provided on both axes.ii)Scale intervals must be consistent.iv)Scale chosen must be able to accommodate all the plots whether plotted or not.PLOTTING ……………………………… 1mki)Award 1 mk for 4 - 5 plotsii)Award ? mk for 3 plotsiv)Award 0 mk for 1 - 2 plotsSHAPE ……………………………………1mk-award 1 mk for line of best fit.-The line should pass through at least three correctly plotted points, otherwise penalize fully.c)……………………………………….. 2mkAccept correct value reading ofsec at 650 C for 1 mkCalculations:= correct value reading ? mkPage | 20Chemistry paper 1, 2&3t =? mkQUESTION 2Observationi) White ppt, ? mk soluble in excess ( ? mk)ii) White ppt, (? mk) insoluble in excess( ? mk)iii) Yellow ppt, (? mk)iv) White ppt, (? mk) white ppt dissolves on heating(? mk)b) i. Burns with yellow sooty/smoky flame ( ? mk)reject yellow aloneii) It dissolves to form a colourless solution AcceptColourless solution formed without dissolves c) i) Effervescence / bubbles / fizzing ( 1 mk) Reject: Hissingii) Orange colour persists or remains the same. AcceptOrange colour of potassium dichromate does not turn to green for 1 mkReject: yellow colour persists.iii) KMnO4 is decolourised ( 1 mk)AcceptKMnO4 changes from purple to colourless (1mk) RejectSolution turns colourless or becomes colourless or remains colourless.InferencesAl 3+ ,Pb2+ or Zn 2+ present.Conditions-If all 3 mentioned ……….. 1mk-If only 2 mentioned …….. ? mk-If only 1 mentioned ………0mks (2 marks)Al 3+, (? mk) or Pb2+ present. ( ? mk)(2 marks)Pb2+ present ( ? mk)Cl- present.-A long chain hydrocarbon or ( ? mk)-Unsaturated organic compound or ( ? mk)-A hydrocarbon with high carbon: hydrogen ratio.Or\/C = C or- CC -/\Rejecti) C = C orC Cii) Carbon carbon double or triple bond in words. iii) alkenes or alkynes-Polar organic compound or polar.AcceptSoluble salt ( ? mk) soluble compound ( ? mk) Presence of : - CoH+ / H30+ ( 1mk)Accept-Acidic compound-Organic Acid-Carbonic acid-Acidic solution ( for ? mk)Absence of R - OH ( 1mk)N:B Penalize for and other contradiction functional group.\/C = C or - C C - present ( 1mk)/\AcceptUnsaturated organic compound ( for ? mk) NB: Penalize fully for any contradiction functional groupe.g R - OH or unsaturated hydrocarbons. Page | 2100Chemistry paper 1, 2&3 CENTRAL KENYA NATIONAL SCHOOLS JOINT MOCK - 2016 233/1 CHEMISTRY PAPER 1 (THEORY) JULY/AUGUST, 2016 TIME: 2 HOURS 1.Two elements A and B have electronic configurations 2.8.3 and 2.6 respectively.(a) To which group and period does element B belong?(1mk)(b) If the two react, what is the formula of the compound they form?(1mk)2.600cm? of oxygen gas diffused through a porous hole in 50 seconds. How long will it take 80cm? of sulphur (IV) oxide todiffuse through the same hole under the same conditions (S = 32, O = 16).(3mks)3.Study the scheme below and answer the questions that follow.FeSO4(aq) Step ICl2(g)Step IIHeatYellow solid FBrown solid FSolid + waterAddition ofNaOH andfiltration(i) Write down the formula of the yellow solid F.(1mk)(ii) What property of chlorine is shown in Step I?(1mk)(iii) Write an equation for the reaction which occurs in Step II.(1mk)4.Describe how a solid sample of lead (II) sulphate would be prepared using the following reagents: dilute nitric (V) acid, lead(II) carbonate solid sodium sulphate and distilled water.(3mks)5.Using dots (?) and crosses (x), show bonding in:(a) The compound formed when nitrogen reacts with fluorine (atomic numbers F = 9, N = 7).(2mks)(b) Sodium oxide (atomic numbers Na = 11, O = 8).(2mks)6.M grammes of a radioactive isotope decayed to 5 grammes in 100 days. The half-life of the isotope is 25 days.(a) What is meant by half-life?(1mk)(b) Calculate the initial mass M of the radioactive isotope.(2mks)7.Determine the oxidation number of:(i) Manganese in KMnO4.(1mk)2?(ii) Chromium in Cr2O7(1mk)8.An element X is atomic number 3, relative atomic mass 6.94 and consists of two isotopes of mass numbers 6 and7respectively.(a) What is the mass number of the more abundant isotope of X?(1mk)(b) Calculate the relative abundance of each of the isotopes.(2mks)9.In an experiment to investigate the conductivity of a substance a student used the set up shown below. The student noticedthat the bulb did not light.(i) What had been omitted in the set up?(1mk)(ii) Explain why the bulb lights up when the omission is corrected.(1mk)10. Name the process that takes place when:(i) Fats or oils are hydrolyzed using an alkali.(1mk)(ii) Sulphur is added to rubber in the manufacture of rubber tyres.(1mk)11.(a) Name two cations responsible for hard water.(2mks)(b) Name two chemicals that are used to remove hardness of water.(2mks)Page | 2200Chemistry paper 1, 2&3 12.Ethanol (CH3CH2OH) and dimethylether (CH3OCH3) are two compounds with the same molecular mass. Explain whyethanol has a much higher boiling point (78.2?C) than dimethylether (-24?C).(2mks)13.Classify the following as either compounds or mixtures.(3mks)SubstanceType of substance(a) Air(b) Salt solution(c) Sugar14.(a) What is meant by molar heat of formation?(1mk)(b) Calculate the molar enthalpy of formation of ethyne (C2H2) given the following.C2H2 + 5/2O2(g) ? 2CO2(g) + H2O(l)?H = -1300kJ/molC(S) + O2(g) ? CO2(g)?H = -394kJ/molH2(g) + 1/2O2(g) ? H2O(l)?H = -286kJ/mol(2mks)15.Study the information in the table below and answer the questions that follow:Solubility (g/100g water)Saltat 50?Cat 80?CG4358Y82138A mixture containing 40g salt G and 120g salt Y in 100g of water at 80?C was cooled to 50?C.(a) Which salt crystallized out? Give reason.(2mks)(b) Calculate the mass of the salt that crystallized out.(1mk)16.When the oxide of metal Z is heated in the presence of metal X, it is reduced.The oxide of metal X is reduced by metal Y. Arrange the three metals in order of increasing reactivity.(2mks)17.The molecular formula mass of gas A is 28 and its empirical formula is CH2.(a) Determine the molecular formula of gas A (C = 12.0, H = 1.0).(2mks)(b) Write the equation of the reaction between A and 1 mole of chlorine gas.(1mk)18.State one use of each of the following apparatus in the laboratory.(3mks)(i) Dessicator.(ii) Crucible.(iii) Deflagrating spoon.19.(a) State the two conditions necessary for rusting to occur.(1mk)(b) State two reasons why tin coating is used in food cans.(2mks)20.Describe how a pure sample of copper turnings can be obtained from mixture of copper turnings and zinc carbonate.(3mks) 21. The diagram below shows sports of pure substances A, B and C on a chromatography paper. Spot D is that of a mixture. Base lineABCDAfter development A, B, C were found to have moved 4cm, 1.5cm and 3cm respectively. D had separated into two spotswhich had moved 3cm and 4cm.(i) On the diagram show the positions of all the spots after development.(3mks)(ii) Identify the substances present in the mixture D.(1mk)22. Chlorine is used to prepare vinyl chloride (chloroethene) CH2 = CHCl.(i) State why vinyl chloride (CH2 = CHCl) undergoes addition polymerization.(1mk)(ii) Name the polymer formed.(1mk)(iii) Complete the following equation to show how the two monomers combine during polymerization.(1mk)CH2 = CHCl + CH2 = CHCl?23. Explain how a sample of CH3CH2CH2OH could be distinguished from a sample of CH3CH2COOH.(2mks)24. A form on student was supplied with a colourless liquid suspected to be water.(i) Describe one chemical test that could be carried out to show that the liquid was water.(1mk)(ii) How could it have been shown that one liquid was pure water?(1mk)25. During extraction of copper, the ore is first concentrated and roasted to producecopper (I) sulphide.(a) Name the ore from which copper is commonly extracted.(1mk)Page | 2300Chemistry paper 1, 2&3 (b) Write an equation for the reaction in which copper (I) sulphide is produced by roasting the ore in air.(1mk)(c) Give one effect that the process in (b) above could have on the environment.(1mk)(d) Give one use of copper metals.(1mk)26. Study the scheme below and answer the questions that follow.Dry CO2(g)Hot charcoalKOHGas X(i) Write an equation involving hot charcoal and dry carbon (IV) oxide gas.(1mk)(ii) Name gas X and state one chemical property of the gas.(2mks)27. How does the use of manganese (IV) oxide in the laboratory preparation of chlorine gas differ from its use on the laboratorypreparation of oxygen gas.(1mk)28. Briefly explain the following observations.(i) Alkaline earth metals are generally less reactive than the alkali metals.(1mk)(i) The order of reactively increases down group I elements but decreases down group (VII) elements.(2mks)29. Study the table below showing tests carried out on a sample of water and results obtained then answer the questions thatfollow.TESTS(i)Addition of NaOH solution dropwise until in excess.(ii)Addition of aqueous NH3(aq) dropwise until in excess.(iii)Addition of dilute HCl acid followed by BaCl2 solution.(a) Identify the anion present in the water.(b) Write an ionic equation for the reaction in (iii) above. (c) Write the formula of the complex ion formed in (ii) above.RESULTSWhite precipitate formed which dissolve in excess. Colouress solution obtained.White ppt is formed.(1mk)(1mk)(1mk) Page | 2400Chemistry paper 1, 2&3 CENTRAL KENYA NATIONAL SCHOOLS JOINT MOCK - 2016 233/2 CHEMISTRY PAPER 2 (THEORY) JULY/AUGUST, 2016 TIME: 2 HOURS 1.(a) The grid given below represents part of the periodic table. Study it and answer the questions that follow. Letters do notrepresent the actual symbols of the elements.ABCDEF(i) What name is given to the group of elements to which C and F belong?(ii) Which letter represents the element that is the least reactive?(?mk)(iii) What type of bond is formed when B and E react? Explain.(2mks)(iv) Write the formula of the compound formed when D and oxygen gas reacts.(v) On the grid, indicate with a tick (?) the position of element G which is in the third period of the periodic table and formsG3- ion.(1mk)(b) Study the information in the table below and answer the questions that follow. Letters do not represent the actualsymbols of the substances.SubstanceMelting pointBoiling pointSolubilityDensity at room temp. (g/cm?)(?C)(?C)in waterH-11778.5Very soluble0.8J-78-33Very soluble7.7 x 10-4K-2377Insoluble1.6L-219-183Slightly soluble1.33 x 10ˉ?(i)Which substance would dissolve in water and could be separated from the solution by fractional distillation. Give a reason.(2mks)(ii)Which substance is a liquid at room temperature and when mixed with water, two layers would be formed.(1mk)(iii) Which letter represents a substance that is a gas at room temperature and which can be collected.IOver water? Explain.(2mks)II By downward displacement of air?(Density of air = 1.29 x 10-3g/cm? at room temperature).(1mk)2.A student fro Nyeri High School wanted to determine the enthalpy change of combustion when a hydrocarbon with theformula C6H14 was burnt. The following are the results of the experiment done.Mass of water= 100gInitial temperature= 18.0?CFinal temperature= 58.0?CMass of the hydrocarbon burned= 0.43gSpecific heat capacity of water= 4.2Jg-1k-1(a) Write a balanced equation for the combustion of the hydrocarbon.(1mk)(b)(i) Calculate the amount of heat given out in kJ when 0.43g of the hydrocarbon burn in air.(2mks)(ii) Calculate the number of moles of the hydrocarbon that were burnt.(1mk)(iii) Calculate the molar enthalpy of combustion of the hydrocarbon.(2mks)(c) The theoretical value of the heat released when 1 mole of the hydrocarbon is burnt is 4194.7kJ/mol-1. Give two reasons why the value obtained from this experiment is less than the theoretical value.(1mk)(d) The diagram below shows an energy level diagram for the formation of magnesium chloride. Study it and answer thequestions that follow.EnergyMg+ 2Cl?HBMgCl2(S)?HC?HAMg+ 2ClReaction path (i) State the enthalpy changes represented by A,B and CPage | 2500Chemistry paper 1, 2&3 (ii) What is the relationship between ?HA, ?HB, and ?HC.(?mk)(e)(i) Define heat value of a fuel.(1mk)(ii) Give two reasons why wood and charcoal are chosen for domestic heating.(2mks)3.(a) Use the standard electrode potentials for A, B, C, D and F given below to answer the questions that follow.E? (Volts)2?A ? aq ?2 ?? 2 eA(S)-2.90? B?aq?? 2eB(S)-2.38??C?aq?? e?C2(g)0.002??D?aq?? 2eD(S)+0.34?F2(g) + e-F(aq)+2.87(i) Which element is likely to be hydrogen? Give a reason for your answer?(2mks)(ii) What is E? the strongest reducing agent?(1mk)(iii) Calculate the e.m.f of the cell that would be formed when half cells of B and D are combined.(1mk)(b) Aqueous copper (II) sulphate was electrolysed using the set up shown below.(i) When the switch was closed, a gas was produced at electrode B.Which electrode is the anode?(1mark)(ii) Write the half equation for the reaction at electrode B.(1 mark)(iii) What happens to the PH of the electrolyte above during electrolysis? Explain.(2 marks)(iv) If carbon electrodes were replaced with copper electrodes in the cell above, write the equations for the reaction thatwould occur at the anode.(1mark)(c) During electrolysis of aqueous copper (II) sulphate using copper electrodes, a current of 0.2 amperes was passed through thecell for 5 hours. Determine the change in mass of the cathode that occurred as a result of the electrolysis process(Cu = 64, IF = 96,500C).(3mks)4.(a)(i) What are unsaturated hydrocarbon compounds?(1mk)(ii) Name the following organic compound.(1mk)O // CH3CH2CH2C ? OCH2CH3 iii) Draw the structure of the following compound 2-methylbutan-l-ol. (1mk) Page | 2600Chemistry paper 1, 2&3(b)The scheme below shows a series of reactions starting with propanol.Solution A + H2K(S)H+/KMnO4CH3CH2COOHStep ICon H2SO4NaOHFStep III CH3CH2CH2OHConcH2SO4180?CBCH2CHCH3Step IICH3?CH2 ? C?GHnStep IVheatProduct C + H2O(l)HClECH3CH31 mole of Cl2 gasCompound D + HCl (i) Name the type of reaction in Steps I and II.(1mk)(ii) Write equation for the reaction that takes place in Step III.(1mk)(iii) Name substances A, D, E and F.(2mks)(iv) Draw the structural formula of compound C.(1mk)(v) Give one disadvantage of continued use of substance G.(1mk)(vi) State the type of reaction involved in formation of compounds B and D.(1mk)(vii) If the relative molecular mass of G is 35, 700, determine the value of n.(2mks)(c) Below are structures of two cleansing agents. R - COO-Na+ ? X ?R -OSO 3Na+ ? Y (i) Identify the cleaning agent suitable for use in water containing MgSO4.(ii) State one disadvantage of using this cleaning agent.(1mk)Page | 2700Chemistry paper 1, 2&3 5.The flow chart below shows the large scale manufacture of ammonia gas and some ammonium compounds. Study it andanswer the questions that follow.Dry hydrogen gasDry nitrogen gasPurifiers Compressors Heat exchanger Catalytic chamber Step IStep 2Compound BAmmonia gasCompound AHNO3H2SO4WaterCompound C(a)What are the sources of the following raw materials?(i) Hydrogen gas.(?mk)(ii) Nitrogen gas.(?mk)(b)What optimum conditions are needed during the manufacture of ammonia in the :(i) Compressor.(1mk)(ii) Catalytic chamber.(1mk)(c)Why should the gas be passed through the compressor.(1mk)(d)Write an equation for the reaction that occurs in Step I.(1mk)(e)Give one use of Compound B.(1mk)(f)Calculate the percentage of nitrogen in Compound A.(2mks)(g)IWhat observation would be made if Compound C was added to a sample suspected to contain copper (II) ionsdropwise then in excess?(2mks)II Name the compound formed when Compound C is added in excess. (1mk)(h)Study the equation below and use it to answer questions that follow.N2(g) + 3H2(g)2NH3(g)?H = -VeWhat would be the effect on the yield of ammonia gas when:Ipressure is increased.(1mk)II Temperature is decreased.(1mk)Page | 2800Chemistry paper 1, 2&3 6. Study the flow chart below and answer the questions that follow. Concentrated hydrochloric acid + Solid P BrownPotassiumH2S(aq)Yellow gas QSolid Usolution R iodideCold dilutesodium hydroxide Step I Aqueous solution Lead nitrate solution White solid T (a)Give the names of the following.(3mks)(i)Solid P(ii)Solid U(iii)Solid T(b)Write the equation for the reaction taking place in Step I.(1mk)(c)Write the equation for the reaction between concentrated hydrochloric acid and solid P.(1mk)(d)Explain what would happen if hot concentrated sodium hydroxide was used in place of cold dilute sodiumhydroxide.(1mk)(e)State two differences between bleaching by chlorine and bleaching by sulphur (IV) oxide.(2mks)ChlorineSulphur (IV) oxide(f)When chlorine water is left under sunlight, the yellow fades to form a colourless solution. Use a chemicalequation to explain this observation.(1mk)(g)Explain two pollution effects caused by chlorine and its compounds to the environment.(2mks)7.The flow chart below is for the extraction of iron metal. Study it then answer the questions that follow.Gas P RoastingSFe2O3(S)furnaceTBlasts ofhot air(a)Identify:(i)Gas P(ii)Solid Q(iii) Solid R(b) Name the main ore used during extraction of iron. (c) Identify one substance present in the slag.CO(g)SlagQGas P + hot airR(3mks)(1mk)(1mk) (d) Write the equation for the reaction that takes place leading to formation of solid S.(1mk)(e) Give the role of solid R in the process.(1mk)Page | 29Chemistry paper 1, 2&3 233/3 CHEMISTRY PAPER 3 (PRACTICAL) JULY/AUGUST 2016 CONFIDENTIAL CENTRAL KENYA NATIONAL SCHOOLS JOINT MOCK - 2016 In addition to apparatus and fittings found in a chemistry laboratory, each candidate will require the following: 1.About 150cm? of solution A, labelled as solution A.2.About 150cm? of solution B, labelled as solution B.3.About 80cm? of solution C, labelled as solution C.4.One pipette (25.0ml).5.One pipette filler.6.One burette.7.One 250ml volumetric flask.8.One label.9.500cm? of distilled water.10. Three conical flasks. 11. 10mls measuring cylinder (one) 12. One 100mls measuring cylinder. 13. One boiling tube. 14. Six test tubes. 15. One 100mls plastic beaker. 16. One thermometer. 17. 1g of solid X, supplied in a stoppered container. 18. Solid F (0.2g), supplied in a stoppered container. 19. One spatula. 20. 1g of NaHCO3 in an envelope/or a stoppered container. Access to:1.Phenolphthalein indicator supplied with a dropper.2.Bunsen burner.3.Acidified potassium dichromate (VI) supplied with a dropper.4.Universal indicator supplied with a dropper.5.PH chart (4 - 11)6.2M NaOH.7.2M NH4OH8.0.1M NaCl.9.Acidified barium chloride.NOTES:?Solid X is Al2(SO4)3.16H2O, molecular weight = 630.38.?Solid F is ascorbic acid C6H8H6, molecular weight 176.13?Solution A is prepared by taking 180cm? of conc. HCl (gravity 1.18), and adding it to 600cm? of distilled water in a 1 litrevolumetric flask and adding it to the mark.Label this as solution A.?Solution B is prepared by dissolving 80g of NaOH pellets in 800cm? of distilled water, transfer to 1 litre volumetric flask andadd distilled water up to the mark, label this as solution B.?Solution C is prepared by dissolving 25g of ethane dioic acid (H2C2O4.2H2O).(Also called oxalic acid) in 600cm? of distilled water, transfer to 1 litre volumetric flask and add distilled water to the mark,label this as solution C.?Acidified potassium dichromate (VI) is made by dissolving 3.16g of solid K2Cr2O7 in600cm? of 2M H2SO4 and diluting it with distilled water to make 1 litre.Page | 30Chemistry paper 1, 2&3 CENTRAL KENYA NATIONAL SCHOOLS JOINT MOCK - 2016 233/3 CHEMISTRY PAPER 3 (PRACTICAL) JULY/AUGUST, 2016 TIME: 2? HOURS 1.You are provided with:-Acid A labelled solution A.-2.0M sodium hydroxide solution labelled solution B.-Solution C containing 25.0g per litre of an alkanoic acid.You are required to: (a) Prepare a dilute solution of sodium hydroxide, solution B. (b) Determine the: (i) molar mass of the alkanoic acid. (ii) reaction ratio between sodium hydroxide and acid A. PROCEDURE I Using a pipette and a pipette filler, place 25.0cm? of solution B into a 250.0ml volumetric flask. Add about 200cm? of distilled water. Shake well. Add more distilled water to make up to the mark. Label this solution D. Retain the remaining solution B for use in Procedure II. Fill a burette with solution C. Using a clean pipette and a pipette filler, place 25.0cm? of solution D into a 250ml conical flask. Add two drops of phenolphthalein indicator and titrate with solution C. Record your results in table 1. Repeat the titration two more times and complete the table. Table IIIIIIIFinal burette reading (cm?) Initial burette reading (cm?) Volume of solution C (cm?) added Determine the: (i) Average volume of solution C used.(1mk)(ii) Concentration of solution D in moles per litre.(1mk)(iii) Concentration of the alkanoic acid in solution C in moles per litre(1 mole of the acid reacts with 3 moles of the base).(1mk)(iv) Molar mass of the alkanoic acid.(1mk)PROCEDURE II Fill a clean burette with solution A. Place 5cm? of solution A into a 100ml beaker. Measure the initial temperature of solution A in the beaker and record it in table II. Using a 10ml or a 100ml measuring cylinder, measure 25cm? of solution B. Add it to solution A in the beaker and immediately stir the mixture with the thermometer. Record the maximum temperature reached in table II. Repeat the experiment with other sets of volumes of solutions A and B and complete the table. Table II Volume of solution A (cm?).5913172125Volume of solution B (cm?).2521171395Maximum temperature (?C).Initial temperature (?C).Change in temperature, ?T.(6mks)(a) On the grid provided, plot a graph of ?T (Vertical axis) against the volume of solution A.(3mks)(b) From the graph, determine the volume of solution A which gave the maximum change in temperature.(1mk)(c) Determine the volume of solution B that reacted with the volume of solution A in (b) above.(1mk)(d) Calculate the:(i) ratio between the volumes of solution A and B that neutralized one another.(1mk)(ii) concentration in moles per litre of the acid in solution A.(Assume that the volume ratio is the same as the mole ratio).(1mk)2.(a) You are provided with a solid X. Carry out the tests that follow.Write your observations and inferences.(i) Place half a spatula endful of solid X in a clean dry test tube. Heat gently and then strongly until no further change.ObservationsInferences(1mk)(1mk)(ii) Dissolve the remaining solid X in about 10cm? of distilled water.Page | 31Chemistry paper 1, 2&3 Divide the solution into four portions. I To the first portion, add 2M sodium hydroxide solution drop wise until in excess. ObservationsInferences(1mk)(1mk)IITo the second portion, add 2M ammonia solution dropwise until in excess.ObservationsInferences(1mk)(1mk)IIITo the third portion, add 3 to 4 drops of sodium chloride.ObservationsInferences(1mk)(1mk)IVTo the fourth portion, add three drops of acidified Barium chloride solution.ObservationsInferences(1mk)(1mk)3.You are provided with a solid F. Carry out the following tests and record your observations and inferences in the spacesprovided.(a)Take one half a spatula end full in a clean spatula and ignite in a non luminousflame.ObservationsInferences(1mk)(?mk)(b)Place all the remaining solid F in a dry test tube. Add about 10cm? of distilled water and shake the mixture. (Retain themixture for use in tests (c), (d) and (e).ObservationsInferences(?mk)(1mk)(c)Using 2cm? of the mixture obtained in (b) above, determine the pH of the mixture.MethodObservationsInferences(1?mks)(?mk)(d)To 2cm? of the mixture obtained in (b) above, add all the sodium hydrogen carbonate provided.ObservationsInferences(1mk)(1mk)(e)To 2cm? of the mixture obtained in (b) above, add three drops of acidified potassium dichromate (VI).ObservationsInferences(1mk)(1mk)Page | 3200Chemistry paper 1, 2&3 CENTRAL KENYA NATIONAL SCHOOLS JOINT MOCK - 2016 233/1 CHEMISTRY PAPER 1 MARKING SCHEME1.2.(a) Group 6Period 2(b) A2B360cm? ? 50 sec 80cm?? 80 ? 5066= 66.67t A? M AORR At BM B? 66 67 ?32= 94.28 sec? M B64R60B50?MA3280 ?80326032?? ?5064 ? = 94.28 sec3.(i) FeCl3(ii) Oxidising(iii) 2Fe(OH)3(S) ? Fe2O3(S) + 3H2O(l)4.React lead (II) carbonate ? with dilute HNO3acid to form Pb(NO3)2. ?-Add water to solid Na2SO4 to from Na2SO4 solution-React Pb(NO3)2 solution with ? Na2SO4 solution; a white ppt is formed.-Filter and wash the residue.-Dry the residue ? between filter papers.5.(a)(b)6.(a) Time taken for a given mass of radioactive isotope to reduce to half.(b)Nooft12?10025?41stt12ndt13rdt14tht15 g22? ? ? ? ? 10 g ? ? ? ? ?2220 ? ? ? ? ? 40 ? ? ? ? ? 80 g ? Initial mass is 80g 7.(i)(+1 x1) + (1 x ?) + (4? - 2) = 01 + ? - 8 = 0? = +7(ii)(? x 2) + (7? - 2) = -22? - 14 = -2? = +6Page | 3300Chemistry paper 1, 2&3 8.(a)7(b) Let % of isotope 7 be ?? % of isotope 6 = 100 - ?7?6 ?100???100? ? 6 94100 7? + 600 - 6? = 694 ? = 694 - 600 ? = 94% Isotope - 7 is 94% Isotope - 6 is 6% 9.(i) Heat(ii) PbBr2 melts. Molten PbBr2 contains mobile ions which conduct electric current.10.(a) Saponification.(b) Vulcanisation. 11. (a) Calcium ions. ?? Magnesium ions. ?? (b) Sodium carbonate. ?? Calcium hydroxide. ?? Ammonia solution. Sodium permutit.(Any two)12.Ethanol has hydrogen bonds while diethylether does not have ?? diethylether has only van der waals forces ?? hydrogenbond are stronger than van der waals forces. ??13.(a) Mixture ??(b) Mixture ??(c) Compound ??14.(a) Enthalpy change when one mole of a compound is formed from its gaseous ions ?? under standard conditions.(b)?Hf = 2(-394) - 286 - (-1300) ??= +226kJ/mole ??15.(a) Salt Y ?? at 50?C only 82g of the 120g salt Y dissolve. ??(b)120 - 82 ??38g ??16.Z<X<Y ??17.(a)14n = 28n = 2 ?? MF = (E.F)n = (CH2)2 = C2H4 ?? (b) C2H4(g) + Cl2(g) ? C2H4Cl2(g) ?? 18. (i) For drying substances/keeping substances free from moisture. ?? (ii) For heating solids that require strong heating. ?? (iii) For holding substances being burned. ??19.(a) Presence of water.Presence of oxygen/air. (b) - Tin is non-toxic - Tin is unreactive. - Does not corrode easily. 20.Add dilute hydrochloric acid to the mixture ?? filter ?? to obtain copper turnings residue, wash and dry ?? the residue.21.(i)(ii) C and A.22.(i) It is unsaturated.(ii) Polyvinyl chloride.(iii)H Cl H Cl????C ? C ? C ? C????H H H HPage | 3400Chemistry paper 1, 2&3 23. (a) Add a sample of each to Na2CO3 ?? in separate test tubes. There is effervescence ?? in one with CH3CH2COOH but no effervescence ?? in the one with CH3CH2CH2OH. ?? (b) Add 3 drops of H+/KMnO4 to a sample of each in a test tube; purple colour is decolourised in CH3CH2CH2OH and purple colour remains in CH3CH2COOH. (c) Add 3 drops of H+/K2Cr2O7 to a sample of each in a test tube; in CH3CH2CH2OH, orange colour turns to green but in CH3CH2COOH, orange colour is retained. 24.(a) Add the colourless liquid to:-Anhydrous copper (II) sulphate which changes colour from white to blue.-Anhydrous cobalt (II) chloride which changes colour from blue to pink.-Any one collect.(b)-Determine its boiling point which is 100?C or freezing point which is O?C.-Determine its refractive index.-Determine its density which is 1g/cm?25.(a) Copper pyrite.(b) CuFeS2(S) + 4O2(g) ? 3SO2(g) + 2FeO(S) + Cu2S(S) (d) - Making cooking utensils. - Making electrical wires. - Making coins and ornaments. - Making roofing sheets. - Making alloys. 26. (i) CO2(g) + C(S) ? 2CO(g) (ii) Carbon (II) oxide - reducing agent. 26.Used as an oxidizing agent ?? in the preparation of Cl2(g) while used as a catalyst ?? in the preparation of oxygen.Any 1 correct ??28.(i) Both group 1 and (ii) elements results by losing electrons. ??-Alkaline earth metals have move protons hence attract their electrons more ?? than the alkali metals and therefore cannotdonate them readily.(ii)-As you move down group 1, the no of energy levels increases making electrons in the outermost energy level to becomeloosely attracted to the nucleus hence easily host.-In group (VII) elements reacts by gaining electrons. As an electron is entering the outermost energy level, it is repelled ?? by the electrons already there. As we go down the group, the energy levels increase hence repulsion/shielding effect increases. 29.(a)2?(b)SOBa42 ??aq ?? SO2?2 ?4? BaSO 4 ?S ? (c)?Zn(NH3)4?? aq ? Page | 3500Chemistry paper 1, 2&3 CENTRAL KENYA NATIONAL SCHOOLS JOINT MOCK - 2016 233/2 CHEMISTRY PAPER 2 MARKING SCHEME1.2.(a)(b)(a)(b)(i)Alkaline earth metals.(ii)A(iii)Covalent - They form bond by sharing electrons.(iv)D2O3/Al2O3.(v)On diagram, period 3 group 5.(i)H - Their boiling points ?? are quite close.(ii)K(iii)IL ?? Its boiling point is lower than room temperature andis?? slightly soluble in water.IIJ ??2C6H14(l) + 1902(g) ? 12 CO2(g) + 14H2O(l)(i)Heat given out ? 100 ? 40 ? 4 2 ?? = 16.8k ?? 1000(ii)Moles?Mass?043??= 0.005moles ??Molarmass86(iii)0.005 moles - 16.8kJ1 mole - ?1 ?168?? = -3360kJ/mol ??000 53.(c)(d)(e)(a)(b)(i)(ii)(iii)(i)(ii)(i)(ii)(i)(ii)(iii)(i)Not all heat is absorbed by 100g of water.Error in measuring temps and masses.Some heat is absorbed by apparatus.A - Heat of solution.B - Lattice energy.C - Hydration energy.?HA = ?HB + ?HC or ?HB = ?HA - ?HC or ?HC = ?HA - ?HBAmount of heat energy produced when a unit mass of a fuel iscompletely burnt in oxygen.(a)Environmentally friendly.(b)Easy to transport and store.(c)High calorific value.(d)Readily available.(e)Non poisonous.(f)Cheap.(g)Burns slowly.C.It has an E? of zero or reference electrode or used as the standard electrode reject has no e.m.f. -2.90V reject A or A2+.Ecell = Ereduced - Eoxidised+0.34 - -2.38?? = +2.72V??B ??? ?(ii)(iii)40 H ? aq? ? 2 H 2 O ?l? ? O 2? g ? ? 4 e??Becomes acidic ?? //PH - lowers/reduces - H+ ions ?? remain in solution as OH- ions are discharged.2? ?(iv) Cu(c)Q = It? S?? Cu? 2 e??? aq ? 0.2 x 5 x 3600 ?? = 3600C ?? Cu2+ + 2e- ? Cus ?? 64g - 2 x 96500C ? - 3600 3600?64= 1.194g ??2?96500Thus cathode increased in mass by 1.194g4.(a)(i)Hydrocarbons with a double or triple bond between adjacentcarbon atoms.(ii)EthylbutanoatePage | 3600?Chemistry paper 1, 2&3(iii)H H H H? ? ? ?H ? C ? C ? C ? C ? OH? ? ?(b)(i)(ii)(iii)(iv)(v)(vi)(vii)H H CH3 HStStep II - Addition polymerizationCH3CH2COONa + NaOH ? CH3CH3 + Na2CO3A - Potassium propanoate E - 1 - Chloropropane / 2 - Chloropropane D - Chloroethane F - Sodium propanoateOCH3CH2 C ? OCH2CH2CH3B - Dehydration.D - Substitution(2 x 3) + (1 x 6) = 4235700n = 850 ?42?850(c)(i)Y(ii)- Non-biodegradable hence causes pollution.- Expensive.5.(a)(i)- Natural gas.- Crude oil.- Electrolysis of acidified water or brine.(ii)Fractional distillation of liquid air.(b)(i)Pressure of 200 - 500atm.(ii)- Finely divided iron.- Temp of 400 - 500?C.(c)To compress gases to high pressure which favour high yield of ammonia.(d)NH3(g) + HNO3(aq) ? NH4NO3(aq)(e)- Used as a fertilizer- Making explosives.(f)(NH4)2 SO4 = (14 x 2) + (1 x 8) + (1 x 32) + (16 x 4) = 13228?100212%132(g)(i)A pale blue ppt on addition of a few drops ?? precipitate dissolve in excess of C to form a deep bluesolution. ??(ii)Tetra amine copper (II) ions.(h)(i)Yield of ammonia increases/more ammonia produced.(ii)Yield of ammonia increases.6.(a)(i)Potassium manganate (VII)(ii)Sulphur.(iii)Lead (II) chloride.(b)2NaOH(aq) + Cl2(g) ? NaCl(aq) + NaOCl(aq) + H2O(l)(c)2KMnO4(S) + 16Cl(l) ? 2KCl(aq) + 2MnCl2(aq) + 5Cl2(g) + 8H2O(l)(d)Sodium chlorate (V) is formed instead of sodium chlorite.(e)ChlorineSulphur (IV) oxide1. Bleaches by oxidationBleaches by reduction2. PermanentTemporaryunlight(f)2HOCl(aq)?S????2HCl(aq) + O2(g)(g)(i)Formation of acidic rain.(ii)Chlorine is poisonous when whaled.(iii)Chlorine compounds e.g. CFCS destroy ozone layer.7.(a)(i)Carbon (IV) oxide.(ii)Coke/carbon.(iii)Calcium carbonate/limestone/marble chips.(b)(i)Haematite(c)- Calcium silicate.- Calcium illuminate.(d)Fe2O3(S) + 3CO(s) ? 2Fe(S) + CO2(g)(e)To produce calcium oxide which react with silica to form slag.Page | 37 00Chemistry paper 1, 2&3 CENTRAL KENYA NATIONAL SCHOOLS JOINT MOCK - 2016 233/3 CHEMISTRY PAPER 3 MARKING SCHEME QUESTION 1 Table IIIIIIIFinal burette reading (cm?)14.314.314.3Initial burette reading (cm?)0.00.00.0Volume of solution C (cm?) added14.314.314.3PROCEDURE ITable 1: 5 marks awarded as follows:1Complete table ………………………………………….. (1mk)1Use of decimals …………………………………………. (1mk)1Accuracy ………………………………………………… (1mk)1Principle of averaging……………………………………. (1mk)1Final answer……………………………………………… (1mk)1(5mks)5Calculations:(ii)Concentration of solution D in moles per litre.Moles of B2?25Moles of D??10002 ? 251000? 005m o les1000 ?? ORMV? MV? ccdd250= 0.200M ??M d?2 ? 25250I? 0 2 M(iii) Concentration of alkanoic acid in C in moles per litre.1Ans ? ii ? above10001 AnsI? ii ? ? 25? ? ?31000OrMa Va? 125 ? OR?Titre3Titre?? = Ans ?? I MbVb31Ans? ii??25Ma??= ?? Ans ??I3Titre(iv)Moles mass of the alkanoic acid.?25?? = Ans ??IAns?iii? abovePROCEDURE IITable II: 6mks distributed as plete table 3mks; award ?mk for each experiment done.-Penalize ?mk once for ?T values greater than 12 of where not all values are beyond 12.-Where ?T is negative, treat as a case of invention and penalize ?mk overall and another ?mk for wrong arithmetic error.-Penalize ?mk for: each of the following:(i) Wrong arithmetic error.(ii) Inverted initial temperature reading.(iii) If the variations in initial temperature is beyond 2?C of the first initial.-Penalize 1mk for unrealistic initial temperature greater than 40?C and less than 10?.-If ?T = 0 or constant through out, with 6 experiments done, award 0mk for complete table.(b) Use of decimals ………………………………………..(1mk)Strictly tied to 3rd and 4th rows onlyAccept whole numbers or to ONE decimal point with .0 or .5 onto two decimal placewith 0.25, 0.05, 0.75 or 0.00 else penalize FULLY.(c) Accuracy ……………………………………………….(1mk)Compare the candidates First initial with the SV and award ? 2?C for 1mkElse penalize FULLY.Page | 3800Chemistry paper 1, 2&3 (d) Trends award ?mk for continuous rise and another ?mk for a continuous or is ?mk for a continuous rise followed by a constant and then ?mk for a continuous drop.Where there is wrong arithmetic, use correct value when awarding the mark for trend. Table II Volume of solution A (cm?).59131721253Volume of solution B (cm?).25211713951Maximum temperature (?C).2527323128261Initial temperature (?C).2121212121211Change in temperature, ?T.46111075(6mks)(a) Graph ………………… 3mks awarded as follows: IAxis …………………….. ?mk.Penalize fully for wrong units but accept if NO units/or omitted. If 1 axes is labelled award zero, inverted axis award zero. Reject T done instead of ?T. II Scale……………………….. ?mk. Scale intervals must be consistent, must accommodate all plots whether plotted or not. NB: If any of above misses, award zero. Award scale even if the axes are inverted, so long as the above conditions are MET.III Plotting ……………………….1mk.For 6 - 5 points correctly plotted award 1mk For 4 - 3 points correctly plotted award ?mk ?3 points correctly plotted award 0mk If scale interval changes, mark within upto scale interval and award accordingly. Accept correct plots from inverted axis. IV Lines…………………………..1mkFirst line must pass at volume = 5cm?Page | 3900Chemistry paper 1, 2&3 (b) Accept correct reading from the graph. ??-If shown on the graph correctly but reading is WRONG award ?mk.-If values of VA is ? 25 award 0mk.-Reject values from wrong graphs (if lines scores a zero).(c) Volume of B30 - Ans (b) above ?? = Ans ??(d)(i) RatiosAns b: Ans c??1 : 1 ??If the ratio is NOT 1; 1 penalize ??2 ? Ans ? ?III(ii) Moles of NaOHM o les o fA ?NaOH ?2? a n s ( c)10002 ? ans ? c ?10001000?Ans ConcofA????.I1000ans(b)= Ans ??212.(a)(i)ObservationsInferences- Vapour droplets condense a theSolid X is hydrated.cooler parts of the test tube. ????- White residue. ?? (1mk) (ii)IWhite ppt dissolves in excessPb2+, Zn2+ or Al3+to form a colourless solution. ?? IIWhite ppt insoluble in excess. ??Pb2+ ?? or Al3+ ??orZn2+ absent ??IIINo white ppt ??Pb2+ absent ??Al2+ present ??IVWhite ppt ??SO2?4 ?? 3(a)ObservationsInferencesBurns ?? with a yellow, ?? sooty, luminousOrganic ?compound high C: H ??flame.unsaturated ??(b)Dissolves ?? to form a colourless solutionPolar Organic compound ??(c)Spot the mixture ?? with universal indicatorWeakly acidic ??solutionH+/RCOOH ?and match ?? against the pH chart. pH of 4 ?? (d)Bubbles ??H+ ??RCOOH(e)Orange H+/K2Cr2O7 turns green ??ROH ??orReducing agent ??Page | 4000Chemistry paper 1, 2&3 KIRINYAGA CENTRAL SUB-COUNTY EFFECTIVE FORTY JOINT EXAMINATION - 2016 233/1 CHEMISTRY PAPER 1 (THEORY) JULY/AUGUST, 2016 TIME: 2 HOURS 1.Name the most suitable method you can use to separate;(a)Xanthophyll and chlorophyll in green leaves.(1 mark)(b)Oil from simsim seeds.(1 mark)2.The table below shows atomic numbers of four elements W, X, Y and Z.ElementWXYZAtomic number2017199(a)Write electron arrangement of the ion of Z.(1 mark)(b)(i)Write the formula of the compound formed between W and X.(1 mark)(ii)Name the bond(s) and structure of the compound in (i) above.(1 mark)3.A student set-up an experiment as shown below. Moist iron wool was placed in a boiling tube and inverted over water.(a)What was observed after two days?(1 mark)(b)Explain the observations.(1 mark)(c)What would be observed if a large piece of iron wool was used?(1 mark)4.Element X is found in period 3 group (IV) it consists of two isotopes 28X and QX. A sample of X was found to consistof 90% of 28X if the relative atomic mass of X is 28.3, work out the number of neutrons in QX.(3 marks)5.Study the table below and answer the questions that follow:ElementAtomic radius (nm)Ionic radius (nm)P0.1680.095Q0.0940.133R0.1240.156S0.1460.086(i)State the elements which are metals.(1 mark)(ii)Identify the strongest reducing agent. Give a reason.(2 marks)6.The diagram below represents an apparatus found in a chemistry laboratory.Give its name.(1 mark)7.Given the following bond energies.C - C(347kJ molˉ?)C - H(413kJ molˉ?)C = C(612kJ molˉ?)H - H(435.9kJ molˉ?)Calculate the enthalpy change of hydrogenation of ethene.(3 marks)8.When hydrogen gas was passed over heated lead (II) oxide in a combustion tube andthe gaseous products cooled, a colourless liquid was obtained.(i)Which chemical test would you use to confirm the colourless liquid above?(1 mark)Page | 4100Chemistry paper 1, 2&3 (ii)What observations were made in the combustion tube?(1 mark)(iii)Write an equation for the reaction between hydrogen and lead (II) oxide.(1 mark)9.The diagram below shows an experiment for investigating electrical conductivity in lead (II) iodide.Study it and answer the questions that follow.(a)On the diagram;(i)Label the cathode.(1 mark)(ii)Show the direction of movement of electrons.(1 mark)(b)Write an equation for the reaction that takes place at the anode.(1 mark)10.(a)State the Graham?s law of diffusion.(1 mark)(b)Two gases A and B diffuse in the ratio 2: 1 if the molecular mass of gas A is 16g, find the molecular mass of B.(2 marks)11.Study the flow chart below and answer the questions that follow.White solid NDilute nitricSolution M +carbon (IV) oxide Add excess NH3(aq) to aAdd few dropsportion of Mof NaOH(aq) toa portion of M White precipitateWhite precipitateHGStep 2HCl(aq)Add excessWhite precipitateNaOH(aq)RColourless solutionQ(a)Identify solid N.(1 mark)(b)Write down the equation for the reaction that leads to the formation of solution Q from the white precipitate G.(1 mark)(c)State the property of precipitate G that is demonstrated by Step 1 and 2.(1 mark)12.The basic raw material for extraction of aluminium is bauxite.(a)Name the method that is used to extract aluminium from bauxite.(1 mark)(b)Cryolite is used in the extraction of aluminium from bauxite. State its role.(1 mark)Page | 4200Chemistry paper 1, 2&3 (c) Aluminium is a reactive metal yet utensils made of aluminium do not corrode easily. Explain this observation. (1 mark)13.The scheme below represents the manufacture of a cleansing agent M.NaOH(aq)R(a)(i)ConcH2SO4Draw the structure of M.RSO3HSolid M(1 mark)14.15.16.17.18.(ii)To which type of cleansing agent does M belong?(1 mark)If chlorine gas is passed over heated iron fillings and the product dissolved in water, a yellow solution is formed. (i) Identify the yellow solution. (1 mark)(ii) What would be observed if aqueous sodium hydroxide solution was added to the yellow solution?(1 mark)(iii) Write an ionic equation for the reaction between the yellow solution and sodium hydroxide.(1 mark)Using excess zinc powder and dilute sulphuric (VI) acid describe how a sample of dry zinc sulphate crystals can be prepared. (3 marks)An organic compound Y was analysed and found to contain carbon, hydrogen and oxygen only. 1.29g of Y on complete combustion gave 2.64g of carbon (IV) oxideand 0.81g of water. Find the empricial formula of Y. (C = 12, H = 1, O = 16).(3 marks)The diagrams below were set up by form 4 students to investigate methods of preventing rusting.(i)It was observed that rusting occurred in set up B and not in set up A. Explain.(2 marks)(ii)State one other method of preventing rusting in iron.(1 mark)An equilibrium exists between the reactants and products as shown in the equation below.? ? ? Br2?aq??H2O?l?OBr?aq??Br?aq??2Hr?aq?(Orange + yellow)(Colourless)(i)Select the species that acts as an acid. Explain.(1 mark)(ii)State and explain the observations made when aqueous sodium hydroxide solution is added to the aboveequilibrium.(1 mark)19.The apparatus shown below were set-up to prepare and collect hydrogen sulphide gas.(a)Name substance G.(1 mark)(b)Complete the set up to show how a dry sample of hydrogen sulphide gas is collected.(2 marks)20.The boiling points of some compounds of hydrogen and some elements in group (IV) and (VI) of the periodic table aregiven poundBoiling point (?C)CompoundBoiling point (?C)CH4-174.0H2O100SiH4-112.0H2S-61(a)Which of the compounds CH4 and SiH4 has stronger intermolecular forces.Give a reason.(1 mark)(b)Explain why the boiling points of H2O and H2S show different trends from that of CH4 and SiH4.(4 marks)21. Radon 222 Ra undergoes alpha decay to form lead, taking 15 days for the original mass to reduce to 6.25%. 84(a)Write the nuclear equation for the reaction.(1 mark)(b)Calculate the half-life of radon.(2 marks)22.Ethanol and pentane are miscible liquids. Explain how water can be used to separate a mixture of ethanol and pentane.(2 marks)Page | 4300Chemistry paper 1, 2&3 23.Illustrate bonding in carbon (II) oxide using dot (?) and cross (x) (C - 6, O - 8).(2 marks)24.The diagram below shows a set-up that was used to prepare and collect a sample of nitric (V) acid.(a)Give a reason why it is possible to separate nitric (V) acid from sulphuric (VI) acid in the set-up.(1 mark)(b)Name another substance that can be used instead of potassium nitrate.(1 mark)(c)Give one use of nitric (V) acid.(1 mark)25.A mixture of kerosene and water was shaken and left to stand, ammonia gas was then bubbled into the mixture followedby a few drops of phenolphthalein indicator. State and explain the observations made.(2 marks)26.Trona is a double salt of sodium with formula Na2CO3. NaHCO3. 2H2O. Trona is collected, dried and heated to convertit to sodium carbonate.(i)Write an equation for the decomposition of trona by heat.(1 mark)(ii)State two uses of sodium carbonate.(2 marks)27.Below is part of a synthetic polymer. Study it and answer the questions that follow.H H H H H H??????? C ? C ? C ? C ? C ? C ???????HHH(i)Draw the structure of its monomer.(1 mark)(ii)Determine the number of monomers making the above compound if its relative molecular mass is 104,000. Thebenzene ring has six carbon atoms and five hydrogen atoms (C = 12, H = 1).(2 marks)28.In an experiment to prepare hydrogen gas using magnesium ribbon and dilute hydrochloric acid, a student plotted volumeof hydrogen gas against time as shown in the sketch below. Volume of hydrogen gas (cm?) Time (seconds) (a)(i) On the same axes, sketch the curve that would be obtained if a few crystals of copper (II) sulphate are added and label itcurve C.(1 mark)(ii) What would be the function of copper (II) sulphate in the reaction?(1 mark)29.1g of element T was completely converted to its chloride, TCl2. The mass of the chloride formed was 3.96g. Calculate therelative atomic mass of element T. (Cl = 35.5).(3 marks)Page | 4400Chemistry paper 1, 2&3 KIRINYAGA CENTRAL SUB-COUNTY EFFECTIVE FORTY JOINT EXAMINATION - 2016 233/2 CHEMISTRY PAPER 2 (THEORY) JULY/AUGUST, 2016 TIME: 2 HOURS 1.The table below gives some elements of the periodic table (not actual symbols) and their atomic masses, atomic numbersand melting points.ElementBCDEFGHIJKAtomic N?781915296161211Atomic mass1416393141912324023Mpt (?C)--63.744-272-223Vary11366998(a)Select two elements with oxidation states of -3.(1 mark)(b)Which elements represents:-(i)the most powerful reducing agent.(? mark)(ii)the most powerful oxidizing agent.(? mark)(c)Which metallic element has the highest first ionization energy?(1 mark)(d)Select two elements which when reacted form a compound that conducts electricity in both molten and aqueous state.(e)Select any two elements which when reacted form a compound that dissolves in water to form an acidic solution.(f)Using dots (?) and crosses (x) to represent valency electrons, draw diagrams to show bonding between B and J.(2 marks)(g)Explain why for some elements the atomic mass is not twice the atomic number.(1 mark)(h)Explain why the melting point of element K is higher than that of element D.(1 mark)(i) Describe how a solid mixture of the sulphate of element K and lead (II) sulphate can be separated.(3 marks)2.The solubilities of two salts D and E are given in the following table in each case the solubility is expressed as grammesper 100g of water.Temperature (?C)1020304050607080Solubility of D1721242934404756Solubility of E35.83636.236.536.837.337.638.0(a)Using these data plot solubility curves for D and E on the same grid.(5 marks)(b)Use your graph to answer the following questions:(i)At what temperature are the solubilities of the two salts equal?(1 mark)(ii)Estimate the solubility of salt D at O?C.(1 mark)(iii) A saturated solution of E in 50g of water at 25?C was evaporated to dryness. What was the mass of the residue? (1 mark)(iv) Two separate 100g of water are saturated at 75?C, one with D and the other with E. What is the difference in mass betweenthe two solutions?(v) The saturated solution obtained were each cooled to 20?C.I Calculate the total mass of the two salts precipitated.II Calculate the mass of each salt dissolved at saturation in 20g of water at 20?C. 3. (i) Study the flow chart below and answer the questions that follow.Sodium chlorideWater + RSolid + QStep IStep IIHydrogen chlorideEthynegas (one mole)Step IIISubstance SProcess ACatalyst /60?CPVC(2 marks)(2 marks)(2 marks)BurnProducts Page | 4500Chemistry paper 1, 2&3 (i)Identify substances Q and R.(2 marks)(ii)Using a chemical equation, show how R reacts with water.(1 mark)(iii)Name and draw the structures of substance S.(2 marks)(iv)Name process A.(1 mark)(v)State two uses of PVC.(1 mark)(b)The scheme below was used to prepare a cleansing agent. Study it and answer the questions that follow.FatNaOH(aq)/BoilSolution of cleansingStep I Step II Solid cleansing agent (i) What name is given to the type of cleansing agent prepared by the method above?(1 mark)(ii) Name one chemical substance added in Step II.(1 mark)(iii) What is the purpose of adding the chemical named in b(ii) above.(1 mark)(iv) Name any other suitable substance that can be used in Step I.(1 mark)(v) Explain how an aqueous solution of the cleansing agent removes oil during washing.(2 marks)4.(a) The standard reduction potentials for five half cells are shown in the table below.Study it and answer the questions that follow. The letters do not represent the actual symbols of the elements.E?(V)A 2 ? aq ? ? 2 e2 ?? ?? 2 A? aq ? ? 1 09? Q?aq??2e?Q?S??0132??R? aq ?2 ?? 2 e? R ? S ? ? 2 37?Y? aq ??25? aq ?? 2 e? 2 e? Y ? S ? ? 0 34?? S 2 ? g ? 0 00 (i) With a reason identify the strongest reducing agent.(1 mark)(ii) Which element is likely to be hydrogen. Explain.(1 mark(iii) Write an equation for the cell formed when Q and Y half cells are joined.(1 mark)(iv) Calculate the e.m.f of the cell in (iii) above.(1 mark)(b) The diagram below represents a mercury cell that can be used in the industrial manufacture of sodium hydroxide. Study itand answer the questions that follow.(i)Name raw material introduced at 2.(? mark)(ii)Name another material that can be used in the cell instead of graphite.(? mark)(iii)Write an equation for the reaction.I that occurs at the anode.(1 mark)II In which sodium hydroxide is produced.(1 mark)(iv)Give two reasons why mercury is recycled.(1 mark)Page | 4600Chemistry paper 1, 2&35.(iv)A current of 100 amperes was passed through the cell for five (5) hours. Calculate the mass of sodiumhydroxide that was produced.(Na = 23.0, O = 16.0, H = 1.0, 1 Faraday = 96500C).(3 marks)Study the flow diagram below and answer the questions that follow.AOreGrinderBRoasted in airCFeO+Cu2S+SO2Heated withRoasted inHeated withuncharged Cu2SGFEsilicaairDSlag tappedoff (a) Give the names of the two ores that can be used in the above process in Stage A.(1 mark(b) What process takes place in Stage B?(1 mark(c) Give the equation for the formation of the slag that is tapped of in Stage D.What is the name of the slag?(2 marks(d) What are the names of the products formed in Stage G?(1 mark(e) What are the main impurities that are contained in the copper obtained in Stage G.(1 mark)(f) Draw a well labelled diagram of the set-up of apparatus that would be used to purify the copper obtained in Stage G.(2 marks)(g) State two uses of copper.(1 mark)(h) What environmental problems would be associated with copper mining?(1 mark)6.(a) Methanol is manufactured from carbon (IV) oxide and hydrogen gas according to the equation.CO2(g) + 3H2(g)CH3OH(g) + H2O(g)?H = -veThe reaction is carried out in the presence of a chromium catalyst at 400?C and 30Kpa under these conditions, an equilibriumis reached when 2% of the carbon (IV) oxide is converted to methanol.(i) Explain how the yield of methanol would be affected if; the manufacturing process above is carried out at, 200?C and apressure of 30Kpa.(2 marks)(ii) A more efficient catalyst is used.(2 marks)(b) In an experiment to determine the molar heat of reaction when zinc displaces copper, 0.4g of zinc powder were added to25.0cm? of 2.0M copper (II) sulphate solution. The temperature of copper (II) sulphate solution was 24?C, while that of themixture was 36?C.(i) Other than increase in temperature, state and explain the observations which were made during the reaction.(3 marks)(ii) Calculate the heat change during the reaction.(Specific heat capacity of the solution = 4.2Jgˉ?Kˉ? and the density of thesolution = 1g/cm?.(1 mark)(iii) Determine the molar heat of displacement of copper by zinc. (Zn = 65).(2 marks7.(a) The diagram below shows an incomplete set-up used to prepare and collect ammonia gas.(i)Name solid T.(1 mark)(ii) Write an equation for the reaction that occurred when a mixture of solid T and calcium hydroxide was heated.(1 mark)(iii) Complete the diagram to show how a dry sample of ammonia gas can be collected.(3 marks)Page | 4700Chemistry paper 1, 2&3 (b) Ammonia gas is used to manufacture nitric (V) acid as shown below. Water Ammonia HighCompoundCoolingCompoundAbsorptionAirtemperaturechambertowerAirNitric (V) acid(i) Name the catalyst used in the above process.(? mark)(ii) Identify compound U.(? mark)(iii) Write the equation for the reaction that took place in the absorption tower.(1 mark)(iv) Ammonia and nitric (V) acid are used in the manufacture of ammonium nitrate fertilizer, calculate the amount of thefertilizer manufactured per day, if the daily consumption of ammonia is 2400kg. Assume that the factory is 100%efficient.(N = 14, H = 1, O = 16).(3 marks)Page | 48Chemistry paper 1, 2&3 233/3 CHEMISTRY PAPER 3 (PRACTICAL) JULY/AUGUST 2016 TIME: 2? HOURS CONFIDENTIAL KIRINYAGA CENTRAL SUB-COUNTY EFFECTIVE FORTY JOINT EXAMINATIONS - 2016 Each candidate will require: -30cm? of solution A, Hydrochloric Acid.-100cm? of solution C.-60cm? of solution F, Sulphuric (VI) Acid (density - 1.84g/cm?)-Solid G, 0.2g of magnesium powder.-Stopwatch.-Thermometer (-10 to 100?C).-100ml beaker.-Phenolphthalein indicator.-Pipette.-Pipette filler.-250ml volumetric flask.-Distilled water.-2 labels.-250ml conical flask.-Burette.-White tile.-Filter funnel.-Stand and clamp.-About 2.0g of solid H.-About 0.2g of sodium hydrogen carbonate.-6 test tubes in a rack.-Test tube holder.-Metallic spatula.-Boiling tube.-Red and blue litmus paper.-About 2.0g of solid J.-50ml or 100ml measuring cylinder.ACCESS TO: 2M NaOH solution. 2M Ammonium hydroxide solution. 2M Barium nitrate solution. 2M Lead (II) nitrate solution. Bunsen burner. Acidified potassium dichromate (VI). Acidified potassium manganate (VII). 2M Nitric (V) acid. NOTE: -Solution F is 0.5M sulphuric (VI) acid (density - 1.84g/cm?).-Solution C is made by dissolving 10g sodium hydroxide and2g sodium nitrate in water to make 1 litre of solution.-Solution A is 2M hydrochloric acid.-Solid J is made by mixing hydrated zinc sulphate andammonium sulphate in the ratio 1: 1.-Solid H is 1.5g maleic acid.Page | 49Chemistry paper 1, 2&3 KIRINYAGA CENTRAL SUB-COUNTY EFFECTIVE FORTY JOINT EXAMINATION - 2016 233/3 CHEMISTRY PAPER 3 (PRACTICAL) JULY/AUGUST, 2016 TIME: 2? HOURS 1.You are provided with:?Solution A - 2.0M Hydrochloric Acid.?Solution C - a solution containing 12g/dm? of sodium hydroxide contaminated with sodium nitrate.?Phenolphthalein indicator.You are required to prepare a dilute solution of hydrochloric acid solution A and use it to determine the purity of sodiumhydroxide in solution C.PROCEDURE-Using a pipette and a pipette filler place 25cm? of solution A into a 250ml volumetric flask.-Add distilled water to make 250cm? of solution. Label this solution B.-Pipette 25cm? of solution B into a 250ml conical flask. Add 2 drops of phenolphthalein indicator.-Fill the burette with solution C and titrate with solution B until there is a permanent colour change.-Repeat the titration two more times and complete the table below.123Final burette reading (cm?)Initial burette reading (cm?)Volume of C used (cm?)(a)Determine the average volume of solution C used.(1 mark)(b)Calculate the number of moles in(i)250cm? of solution B.(2 marks)(ii)25cm? of solution B.(1 mark)(c)Calculate the(i)Number of moles of sodium hydroxide in the average volume of solution C used.(2 marks)(ii)Mass of sodium hydroxide in 1dm? of solution C.(2 marks)(iii) Percentage purity of the sodium hydroxide.(1 mark)2.You are provided with:- Sulphuric (VI) acid, solution F. - 0.2g magnesium, solid G. You are required to determine the molar heat of reaction, ?H between magnesium the acid. PROCEDURE: -Measure 50cm? of solution F using a measuring cylinder and place it in a 100cm? beaker.-Stir the solution gently with a thermometer and take it?s temperature after every half-minute.-Record your results in Table III below.-After one and half minutes, add all of solid G at once. Stir the mixture gently with the thermometer and record thetemperature of the mixture after every half-minute in table III up to the sixth minute.Table IIITime (min)0?11?22?33?44?55?6Temperature (?C)(a)In the grid provided, plot a graph of temperature (vertical axis) against time.(3 marks)(b)From the graph determine the change in temperature, ?T.(1 mark)(c)Calculate the heat change for the reaction using the expression.(Heat change = mass of solution x 4.2 x ?T - assume density of solution = 1.0g/cm?).(2 marks)(d)Calculate the molar heat of reaction of sulphuric (VI) acid with magnesium.(Mg = 24.0).(2 marks)3.IYou are provided with solid J. Carry out the test below to identify the compound.(a)Place ? spatula of solid J in a hard test tube and heat strongly until no further change. Test the gas produced with litmuspaper.ObservationInference(1mk)(1mk)(b)Place the remaining solid J into a clean boiling tube. Half fill it with distilled water and shake well. Divide the solution intofour portions.ObservationInference(1mk)(1mk)Page | 50Chemistry paper 1, 2&3 (i) To the first portion add dilute sodium hydroxide solution dropwise till in excess. ObservationInference(1mk)(1mk)(ii) To the second portion add ammonia solution dropwise till in excess.ObservationInference(1mk)(?mk)(iii) To the third portion add drops of dilute barium nitrate.ObservationInference(?mk)(1mk)(iv) To the fourth portion add a few drops of dilute nitric acid followed by lead (II) nitrate solution and warm.ObservationInference(?mk)(?mk)You are provided with solid H. Carry out the tests below.Write your observations and inferences in the spaces provided.(a) Place about a spatulaful of solid H on a metallic spatula and burn it using a Bunsen burner.ObservationInference(?mk)(1mk)(b) Place the remaining solid H in a boiling tube. Add about 10cm? of distilled water and shake well. Retain the mixture for usein the tests below.ObservationInference(?mk)(?mk)(c) Divide the solution in (b) above into three portions.(i) To the first portion, add a small amount of solid sodium hydrogen carbonate.ObservationInference(1mk)(1mk)(ii) To the second portion, add 1cm? of acidified potassium dichromate (VI) and warm.ObservationInference(?mk)(1mk)(iii) To the third portion, add two drops of acidified potassium manganate (VII).ObservationInference(?mk)(?mk)Page | 5100Chemistry paper 1, 2&3 KIRINYAGA CENTRAL SUB-COUNTY EFFECTIVE 40 JOINT EXAMS - 2016 233/1 CHEMISTRY PAPER 1 MARKING SCHEME 1.(a)Chromatography. (1mk)(b)Solvent extraction. (1mk)2.(a)2.8 (1mk)(b)(i)WX2(1mk)(ii)Bonds - Ionic bonds (?mk)Structure - Giant ionic structure. (?mk)3.(a)Moist iron wool had turned to brown. (1mk)(b)The brown substance (?mk) was rust which occurred due to presence of moisture and oxygen. (?mk)4.?90??10?(?mk)? ? 28 ?? 100 ?2520 ? 10 Q1002520 + 10Q??? ? Q ? ? 28 3? 100?28 3(?mk)1= 2830 10Q= 2830 - 252010Q= 310Q = 31(1mk)Electron arrangement = 2.8.4, Atomic number = 14 (?mk)Number of neutrons= 31 - 14= 17 (?mk)5.(i)P and S (?mk each)(ii)P - It has the greatest atom radius (?mk) hence easily looses an electron. (?mk)6.A pipette (1mk)7.HHHH????C = C + H2? H ? C ? C ? H (1mk)????HHHHEnergy for bond breakingEnergy for bond formationC = C612 = +612C - C347= -3474 C - H4 x 413 = +16526 C - H 6 x 413= -24781 H - H435.9= +435.9-2825KJ+2699.9KJ(?mk)(?mk)Enthalpy change of hydrogenation =+ 2699.9KJ + -2825KJ(?mk)= -125.1KJ(?mk)8.(i) Use of anhydrous copper (II) sulphate, (?mk) if the colour changes from white to blue (?mk) the liquid is water.ORUse of anhydrous cobalt (II) chloride, (?mk) if the colour changes from blue to pink (?mk) the, liquid is water.(ii) A grey solid (1mk)(iii) PbO(s) + H2(g) ? Pb(s) + H2O(g)(1mk)9.(a)Page | 5200Chemistry paper 1, 2&3?(b)Anode2I?l?? I 2 ?s? ??2e(1mk)10.(a)(b)The rate of diffusion of a gas at constant temperature and pressure is inversely proportional to the square root ofits density. (1mk)R A ? M B2 ? 4 ? MBR BA: B2: 12?M AM B(1mk)MB = 8?= 64g(1mk) 11611.(a)Solid N - lead carbonate or PbCO3(1mk)(b)Pb(OH)2(s) + 2NaOH(aq) ? Na2 Pb(OH)4(aq)(c)Amphoterism (1mk)12.(a)Electrolysis.(1mk)(b)To lower the melting point of aluminium oxide. (1mk)(c)Aluminium has a thin oxide layer (1mk) which prevents it fromreacting with oxygen.13.(i)??(1mk)RSO(ii)Soapless detergents. (1mk)14.(i)Iron (III) chloride or FeCl3 (1mk)(ii)A brown precipitate.(1mk)? ?3Na (iii)Fe3?aq??3OH? aq??Fe?OH?3?s??Brownppt?15.React excess zinc powder with dilute sulphuric (VI) acid (?mk). Filter out (?mk) the unreacted zinc powder. Heat(?mk) the solution to saturation point, allow to cool (?mk) Filter out (?mk) the crystals and dry (?mk) them in betweenfilter papers.16.12(?mk)M ass ofC?M a ss o fH?Mass of oxygen(i)Mass(ii)R.A.M44 ? 2 64 ? 0 72 g2(?mk)18? 081 ? 009= 1.29g - (0.72 + 0.09)g= 0.48g (?mk)CHO0.720.090.4812116 (iii)No of moles07200904812116(?mk)0.060.090.03(iv) Mole ratio0060090030030030032 :31(?mk)E . F - C2 H3O(?mk)17.(i)Tin is less reactive than iron hence couldn?t prevent iron from reacting (?mk)with oxygen. While in A magnesium is more reactively (?mk) than iron hence it reacted with (?mk) oxygeninstead of iron.(ii)- Electroplating.-Painting.-Oiling and greasing.-Use of silica gel(1mk) for any one18.(i)H2O (?mk), it donates a proton (H+) (?mk)(ii)Sodium hydroxide reacts with H+ (?mk)The orange/yellow colour fades (?mk) since the equilibrium shifts to the right.Page | 5300222Chemistry paper 1, 2&3 19.(a)Dilute hydrochloric acid HCl).(1mk)(b) (?mk) Correct method of collection - (1mk) Workability - (?mk) 20.(a)S1H4 (?mk) it has a bigger molecular size (?mk) and the strength of intermolecularforces increases with increase in molecular size//it has a higher boiling point.(b)CH4 and S1H4 have van dar waal?s force only (?mk) and hence the boiling pointsincreases with increase in molecular size (?mk) H2O has both van der waal?s forces and hydrogen bonding(?mk) while H2S has only van der waal?s forces. (?mk)222218421.(a)Ra ?Pb +He(1mk)84822111t 12t(b)100 % ? ? ? 50 ???No of half lives = 4 (?mk)15tt25 ??? 12 5 ??? 6 25(?mk) Half life =(?mk) = 3.75 days (?mk4 22.Add water (?mk) to the mixture water mixes with ethanol and forms the lower layer (?mk) while the upper layer ispentane using a separating funnel (?mk) to separate pentane use fractional distillation (?mk) to obtain ethanol fromwater.23.(2mks) 24.(a) Sulphuric (VI) acid is non volatile/less volatile (1mk) hence displaces the less volatile nitric (V) acid from its salt.(b)Sodium nitrate NaNO3). (1mk)(c)- Manufacture of nitrate fertilizers.-Manufacture of explosives.-Manufacture of dyes and drugs-Refining of precious metals.(1mk for any one)25.Pink (1mk) colour appears at the bottom layer, ammonia gas dissolve in water (?mk) which is the bottom layer releasingOH- (?mk) ions which turn phenolphthalein to pink.26.(i)2Na2CO3 NaHCO3.2H2O?h?eat?3Na2CO3(s) + CO2(g) + 5H2O(g) (1mk)(ii)- Manufacture of glass.-Softening of hard water.-Manufacture of soaps and detergents-In paper industry.(2mks for any two)Page | 5400Chemistry paper 1, 2&327.(ii)HH? ?C=C?HNumber of monomers =R MMMass ofmonomerMass of a monomer = 12 x 6 + 5 + 12 x 2 + 3 = 104? 104000 (?mk)(?mk) 104 = 1000 (1mk)28.(a)(i)Volume ofhydrogengas (cm?)(1mk)CTime (seconds) (ii)Is a catalyst(1mk)29.Mass of Cl2 in TCl2 = 3.96 - 1 = 2.96g(?mk)296Moles of chlorine atoms ?35 5? 0 0833(?mk)Moles of T = 1/2 x 0.0833 = 0.041690.04169 moles T ? 1g1 moles T ? ?(?mk)1 ? 10 04169= 23.986g(?mk) (1mk) Page | 5500Chemistry paper 1, 2&3 KIRINYAGA CENTRAL SUB-COUNTY EFFECTIVE 40 JOINT EXAMS - 2016 233/2 CHEMISTRY PAPER 2 MARKING SCHEME 1.(a)B, E(b)(i) D(ii) G(c)J(d)D and G or J and G orD and C or K and G or K and C(e)B and C or I and C or E and C(f)(g)For some elements the number of neutrons is not equal to the number of protons.(1mk)(h)K has stronger metallic bonds ?? since it Comparison must be done in has smallest atomic size ?? hence higherstrength of bonds and size of energy is needed to break.(i)- Add water and stir. ??- Sulphate of K dissolves while PbSO4 doe not.??- Filter - PbSO4 is the residue sulphate of K is filtrate.- Evaporate the filtrate to dryness ?? to obtain solid sulphate of K ??2.(a)(b)(i)55?C ? 1 small square ??(ii)14?C ? 1 small square ??(iii)At 25?C solubility of E is 31g/100g H2O ??? 50g of water contains 15.5g ?? of solute when evaporated (iv)At 75?CD ? 51g/100g H2O ?? = 151g solution ??E ? 38g/100g H2O ? = 151g solutionDifference = 151-138 = 13g ??(v)ISalt D ? 51 - 21 = 30g of soluteSalt E ? 38 - 36 = 2.0g of solutePage | 5600Chemistry paper 1, 2&3 Total mass of solute = 30 + 2 = 32g II Salt D - at 20?C ? 21g/100g H2O 21g ? 100g H2O t? 20g H2Ot ?20 ? 21100?? = 4.2g ?? Salt E at 20?C 36g/100g H2O36g ? 100g H2Oqq? 20g H2O ? 20 ? 36?? = 7.2g ?? 1003.4.(a)(b)(a)(i)(ii) (iii)(iv) (v)(i)(ii) (iii) (iv) (v)(i)(ii)Q - Concentrated sulphuric ??Acid // H2SO4(l)R - Calcium carbide // CaC2CaC2(s) + H2O(l) ?Ca(OH)2(s) + C2H2(g)Chloroethene ?? HH? ?C = C? ?HClPolymerization ??- Artificial leather for clothing, shoes, handbags- Insulation to electric wires.Soapy/soap detergent. ??Concentrated sodium chloride // Brine ??To precipitate out soap. ??Potassium hydroxide // KOH.- Cleansing agent is made of non-polar(hydrocarbon) and polar (head). ??- When mixed with oil/grease, the hydrocarbon end is attracted to oil ?? while the polar stays in water. ??- The oil particles are broken and carried off ?? into the solution.R ?? - Has the highest negative E?value ?? // loses electrons most readily.S or S2 ?? - Has E? value of 0.00 // ??is used as the reference electrode.2? 2? (iii)Y?aq??Q?s??Y?s??Q?aq???(iv)Ecell = +0.34 + 0.13 = +0.47V ??(b)(i)Water ??(ii)Platinum // Titanium?(iii)IAnode?2Cl?aq??Cl2?g??2e??II2NaHg(l) + H2O(l) ? 2NaOH(aq)+ 2Hg(l) + H2(g)OR2Na(s) + 2H2O(l) ? 2NaOH(aq) + H2(l)(iv)- Reduce costs// its economical // Hg is expensive.- Reduce environmental pollution // Hg is poisonous.(v) Q = It = 100 x 5 x 60 x 60?? = 1800000C????2Na? aq?? 2 e? 2 Na Na+ + e- + Hg ? NaHgIF ? 1 mol Na ? 1 mol NaoH ??96500C ? 40g NaOH1800000C ? d d ?5.(a)Chalcopyrite // copper pyrites.Chalcorite(b)Froth floatation.(c) FeO(s) + SiO2(s) ? FeSiO3(l) ??.Iron (II) silicate ??.40 ? 180000096500? 746 1g Page | 5700Chemistry paper 1, 2&3 (d)(Molten) copperSulphate (IV) oxide (e)Iron, zinc, silver, gold, platinum(f) (g)- Manufacture of electric wires, cables and fittings.- Making coins and jewellery - Making alloys- Brass- Bronze - German silver - Manufacture of lightning arrestors. (h) - Respiratory diseases due to emission of poisonous SO2. - Breeding grounds for mosquitoes (large gaping holes left trap stationary water. 6.(a)(i)The yield increased (1mk) the equilibrium will shift from left to the right (1mk) // forward reaction isfavoured. (2mks)(ii)The yield remain the same (1mk) catalyst only change the rate of attainment of equilibrium (1mk) //a catalyst has no effect on the position of the equilibrium.(2mks)(b)(i)- The blue colour of the solution fades. (1mk)- A brown solid is deposited. (1mk)The blue Cu2+ ion (1mk) are discharged to copper (?mk) metal which is brown. (3mks)(ii)Temperature change= 36 - 24 = 12?CHeat change= 25 x 4.2 x 12 (?mk)= 1260 Joules(?mk)(1mk)(iii)Moles Zn used04(?mk) = 0.006154650.006154 moles ? 1260 Joules12601 m ole ?0 00 6154? 1 m k ? ? 204 , 714 9 ?H = -204,745KJ molˉ? ?? (2mks)Total (10mks)7.(i)Solid T - Ammonium chloride (1mk)/ammonium sulphate/ammonium carbonate.(ii)2NH4Cl(s) + Ca(OH)2(s) ? CaCl2(s) + 2NH3(g) + 2H2O(l)(1mk)(iii)(b)(i)Platinum (?mk)(ii)Compound U ? nitrogen (II) oxide/NO(?mk)(iii)NO2(g) + H2O(l) + O2(g) ? 2HNO3(aq) (1mk)(iv)NH3(aq) + HNO3(aq) ? NH4NO3(aq)MM of NH3 = 17 (?mk)MM of NH4 NO3 = 80 (?mk)24000002400000?80Moles NH? ?1mk ? MolesNHNO? ?1mk ?317243217 ? 1000Moles NHNO? 2400000? 1mk ? = 11,294kg (?mk)43802 Page | 5800Chemistry paper 1, 2&3 KIRINYAGA CENTRAL SUB-COUNTY EFFECTIVE 40 JOINT EXAMS - 2016 233/3 CHEMISTRY PAPER 3 (PRACTICAL) MARKING SCHEME 1.123Final reading (cm?)20.019.920.1Initial reading (cm?)0.00.00.0Volume of solution C (cm?)20.019.920.0(a)(b)Complete table- (2mks)Decimals- (?mk)Accuracy- (?mk)(3mks)20 0 ? 19 9 ? 20 1?? = 20.0cm? ??3(i)Number of moles in 25cm? of solution A.? 25 ? 2 ?? 1000 = 0.05 moles ?? No of moles in 25cm? of A = No of moles in 250cm? of B = 0.05 moles. ?? (ii)Moles in 25cm? of B005?25?? = 0.05 moles ??250 (c)(i)NaOH(aq) + HCl(aq) ? NaCl(aq) + H2O(l)Mole ratio = 1: 1 ??Mole of NaOH= Moles of HCl= 0.005 moles ??(ii)Mass of sodium hydroxide in 1dm? of solution C.Moles in 1dm? =1000 ?000 5??20= 0.25 moles ??Mass of NaOH= No of moles x R.M.M= 0.25 moles x 40 ??= 10g ??(iii)Percentage purity.10???12? 100 = 83.33% ??2.Time (min)0? 1Temperature (?C)20.020.020.0Complete table-(2mks)Decimals-Trend-(b)?T = 34 - 20 = 14.0?C(c)Heat change = MC?TMass of solution = 50 x 1g/cm?Mass of solution = 50g? Heat change ? 50 ? 4 2 ? 141? 225.0(?mk)(?mk)(3mks2?30.0332.53?32.5433.04?34.0534.05?34.0634.0 1000 = 2.94kJ(d)Mass of Mg = 0.2gM. mass of Mg = 25g/mol Moles of Mg ? 0 2 = 0.0083mol 240.0083 mol ? 2.94kJ1 mol ? ??1 ?29400083Page | 5900Chemistry paper 1, 2&3 ? Molar heat for r x n = -354.21kJ molˉ?3.I(10mks)Observation(a)- Colourless gas that turns moist red litmuspaper to blue. ??- Colourless droplets of liquid forms on coolerend of t.t. ??Observation(b)Solid dissolves ?? to form a colourless solution. ??Observation(i)White precipitate. ??Soluble in excess. ??Observation(ii)White precipitate. ??Soluble in excess. ??Observation(iii)White precipitate. ??Inference?NH 4present ??- J is a hydrated salt ?? /contains H2O of crystallization.InferenceSoluble salt present. ??Coloured ions absent ???(Fe2+, Fe3+, Cu2+)InferencePb2+, Al3+, Zn2+ present ?All 3 - (1mk)Any 2 - (?mk)1 - (0mk)InferenceZn2+ present ??Inference2? 2? 2?SO,4SO, CO,present ?33 All 3 - (1mk)Any 2 - (?mk)1 - (0mk)Observation(iv)White precipitate. ??Insoluble on warming ??3.II(7mks)SOInference2 ?4 present ?? ExperimentObservationsInferences(a)Burning of solid HH burns with a luminous? C ? C ? ??? orflame/sooty flame. ????C = C????Present/unsaturated cpd.- Long chain organic cpd.(b)Solid H +- Solid dissolves to- Solid H is a polar cpd. ??distilled waterform a colourlesssolution. ??(c)(i)Solution H- Effervescence/+ solid NaHCO3Bubbles of gas ??OC OH Carboxlic group present Solution H +- Solution changes??(ii)acidified K2Cr2O7colour from orange? C = C ? ??? orto green. ????? C ? C ? ??May be presentSolution H +- Purple colour of acidified??acidified KMnO4KMnO4 is decolourised. ??? C = C ? ??? or??? C ? C ?PresentPage | 60Chemistry paper 1, 2&3 NANDI NORTH AND NANDI CENTRAL JOINT EXAMINATIONS 2016 233/1 CHEMISTRY PAPER 1 THEORY JULY / AUGUST 2016 TIME: 2 HOURS 1.Two elements A and B have electronic configurations 2.8.3 and 2.6 respectively.(a) To which group and period does element B belong?(1mk)(b) If the two react, what is the formula of the compound they form?(1mk)2.(a) State Charles? Law.(1mk)(b) The volume of a sample of nitrogen gas at a temperature of 298k and 600 minHg pressures was 4.8 x 10-2m3.Calculate the temperature at which the volume of the gas would be 3.2x102m3 if pressure is constant.(2mks)3.The formula given below represents a portion of polymer.(a) Give the name of the polymer.(1mk)(b) Draw the structure of the monomer used to manufacture the polymer.(1mk)4.In a closed system, aqueous iron (II) chloride reacts with hydrogen sulphide gas as shown in the equation below.2FeCL3(aq) + H2S(g)2FeCl2(aq)+ 2HCl(aq) + S(s)State and explain the observation that would be made if dilute hydrochloric acid is added to the system at equilibrium.(2mks)5.Omolo a student in Form 1 set up an apparatus as shown for the preparation of dry chlorine gas.(a)(i) Name substance W.(1mk)(ii) State a suitable drying agent.(1mk)(b) Identify any two mistakes in the set-up.(2mks)6.The table below shows the results obtained when soap solution was added to different samples of equal volumes of calciumhydroxide solution treated with different amounts of Carbon (IV) oxide.SampleSolutionVolume of soap added to sampleto latherC50cm3 of calcium hydroxide + excess x carbon (IV) oxide.10cm3D50cm3 of calcium hydroxide + little carbon (IV) oxide.2cm37.Hydrogen sulphide gas was bubbled through a solution of zinc nitrate for sometime.(i) State the observations made.(1mk)(ii) Where should the experiment be carried out and why?(1mk)8.The diagram below shows set-up used to burn hydrogen and collect the product.(a)State why it?s necessary to dry the hydrogen gas before igniting it.(1mk)(b)(i) State the precaution that must be taken before igniting the hydrogen.(1mk)(ii) State two uses of hydrogen gas.(1mk)9.The diagram below shows acidic and basic oxides fit into the general family of oxides.(i) State the name given to the type of oxides that would be placed in the shaded region.(1mk)(ii) Give the name of any oxide that could be placed in the shaded region.(1mk)10. Eugene Kipngetich of Form II at Laboret School set up the following experiment with the help of the two laboratory assistants. Metal rods S, T, U and V were cleaned with sand paper and placed in a beaker containing water. A second set was put in a container of steam and a third set was placed in a beaker containing dilute acid. Bubbles of gas and reaction was observed around some of the rods as shown in the diagrams below. (a) It was very necessary to clean the rods with sand paper before dipping them. Explaining.(1mk)(b) Arrange the four metals in order of their reactivity starting with the most reactive.(1mk)11.The following set up was used to investigate some properties of two gases G and H.When beaker B was filled with gas G the level of water in the glass tube rose to point II. When the experiment was repeatedusing gas H, the level of water dropped to point III. Explain these observations.(3mks)12.Paper chromatography was carried out to investigate presence of amino acids in beans. Study the chromatograms below toanswer the questions that follow.What conclusion can be drawn from these results?(1mk)13.Describe how you would prepare a dry sample of lead II chloride starting with lead II carbonate.(3mks)14.(a) A piece of burning magnesium was lowered into a gas jar containing nitrogen oxide. State and explain the observationsmade.(2mks)(b) Write an equation for the reaction in (a) above.(1mk)15.The half equations involved in a cell are:-2H2O(l) + 2e =H2(g) +2OH(aq):E? = - 0.83VPage | 61Chemistry paper 1, 2&3 O2(g) +2H2O(l) + 4e =4OH(aq):E? = - 0.40V(a) Write the overall equation for the electrochemical cell.(1mk)(b) Calculate the e.m.f. generated by a battery consisting of ten cells.(1mk)(c) State one environment advantage of using these cells in spacecrafts.(1mk)16.The structures below are sections of models of the structures of elements P and Q.(i) In which group of the periodic table do the elements belong?I.P(1mk)II.Q(ii) Which of the two elements is a better conductor of electricity? Explain.(1mk)17.Air was passed through reagents as shown below.(i)State and explain the observations made when air is passed through chamber A for a long time.(2mks)(ii) Name one component in C. Explain.(1mk)18.The following set-up shows the heating of a mixture of equal amounts of sodium chloride and ammonium chloride.(a) What is substance K?(1mk)(b) What is the process by which substance K is formed?(1mk)19.In the industrial extraction of lead metal, the ore is first roasted in a furnace. The solid mixture obtained is then fed intoanother furnace together with coke limestone and scrape iron. State the functions of each of the following in this process:-(a) Coke(1mk)(b) Scrape iron(1mk)(c) Limestone(1mk)20.The set-up below was made by a form four student. At the start of the experiment, the bulb did not light.(a) State and explain the observation made when Cl2(g) was bubbled in the water for about 10 minutes.(2mks)(b) Write the chemical equation for the reaction which took place at the cathode.(1mk)21.Use the information below to answer the questions that follow:-Equation:Enthalpy of formation(i) H2(g) + ?O2(g)→ H2O(l)?H1 = -286kJmol-1(ii) C(s)+ O2(g)→ CO2(g)?H2 = -394kJmol-1(iii) 2C(s)+ 3H2(g) + ?O2(g)→ C(s)H2OH(l)?H3 = -277kJmol-1Calculate the molar enthalpy of combustion of ethanol. Given that:(3mks)C(s)H2OH(l) + 3O2(g)→2CO2(g) + 3H2O(l)22.Dry sulphur (IV) oxide was passed through two pieces of coloured silk both in a gas jar as shown in the diagram(a) State the observation in the gas jars.(2mks)(b) What equations to explain your observations in flask II.(2mks)23.Study the diagram below and answer the questions that follow.(i) Write the equation for the combustion of propane.(1mk)(ii) The PH of substance K was found to be less than 7. Explain this observation.(1mk)24.The table below gives some physical properties of substances A, B and C. Study it and answr the questions that follow.Electrical conductivitySubstanceColourM.P (0C)Solubility in waterSolidLiqudABlack114InsolubleNon conductorLiquidBBlack1326SolubleNon conductorConductsCBlack3730InsolubleConductsConductsIdentify the substance that is:(i) Giant atomic structure(1mk)(ii) Ionic structure(1mk)25.Calculate the amount of calcium carbonate that would remain if 15.0g of calcium carbonate were reacted with 0.2 moles ofhydrochloric acid. (C = 12.0 = 1.60, Ca = 40.0)(3mks)26.A certain mass of a metal E1 reacted with excess dilute hydrochloric acid at 250C. The volume of hydrogen gas liberated wasmeasured after every 30 seconds. The results were presented as shown in the graph below.(a)Name one piece of apparatus that may have been used to measure the volume of the gas liberated.(1mk)(b)(i) On the same axis, sketch the curve that would be obtained if the experiment was repeated at 370C.(1mk)(ii) Explain the shape of your curve in (b) (i) above.(1mk)27.(a) Give two reasons why most laboratory apparatus are made of glass.(1mk)(b)The diagrams below are some common laboratory apparatus. Name each apparatus and state its use.28.The equation below shows a reversible reaction.H3O+(aq) + HSO-4(aq)H2O(l) + H2SO4(i) Identify the acid in the forward reaction and explain.(2mks)29.(a) Give two advantages of hard water.(1mk)(b) Explain how water hardness is removed by ion exchange method.(2mks)30.M grammes of radioactive isotope decayed to 5 grammes in 100 days. The half-life of the isotope is 25 days.(a) What is meant by half-life?(1mk)(b) Calculate the initial mass M of the radioactive isotope.(2mks)Page | 62Chemistry paper 1, 2&3 NANDI NORTH AND NANDI CENTRAL JOINT EXAMINATIONS 2016 233/2 CHEMISTRY PAPER 2 THEORY JULY / AUGUST 2016 TIME: 2 HOURS 1.The grid below is a Periodic Table. The letters used are not the actual chemical symbols of the elements. Study the table andanswer the questions that follow.GRJQYDTWUZEXV(a)What name is given to the elements that occupy region X?(1mk)(b)Write an equation to show how element Y forms an ion.(1mk)(c)Compare the atomic and ionic radius of T.(1mk)(d)Explain why the ionization energy of V is lower than that of D.(2mks)(e)Name the chemical family to which E belongs.(1mk)(f)An element A is in period 3 and it loses three electrons to form an ion. Write the electronic configuration of an atom of A.(1mk)(g)Elements D and U combine to form a compound with a giant structure.(i) Name the giant structure.(1mk)(ii) State two characteristics of the structure.(1mk)(h)Write the formula of the compound formed when T and Y react.(1mk)(i)State and explain the change in electrical conductivity from D to T.(2mks)2.(a) An electrolytic cell is set up a form two class to perform an electrolysis of brine using carbon chloride.(i) What is brine?(1mk)(ii) Identify the cations in brine.(1mk)(iii) Identify the ion discharged at anode and name its factor of discharge.(2mks)(b)The diagram below shows an electrochemical cell to determine the E0 of Iron.The reading on the voltmeter is -0.44V.(i) On the diagram show by an arrow the direction of the flow of electrons.(2mks)(ii) State two functions of the salt bridge.(2mks)(iii) Write an equation for the reaction in the Fe2+ / Fe half cell.(1mk)(iv) Identify the reference half cell.(1mk)(v) Calculate the cell emf given that the reference half-cell has an E0 value of 0.00V.(2mks)(vi) Write the cell representation.(1mk)3.(a) The graph below is temperature-time curve obtained when a block of ice is heated from -40C to just over 1000C.(i) Name the heat change occurring in region 2.(1mk)(ii) Identify the state of the substance at region 3.(1mk)(iii) Explain why there is no change in temperature in region 4.(2mks)(iv) In which of the regions is there a solid-liquid mixture?(1mk)(b)To determine the heat of combustion of ethanol, a form four class used the set-up shown below.Table showing observationsMeasurementsValuesSteady final temperature of 50ml of water used.69.50CInitial temperature of water18.00CTemperature change,□ in KInitial mass of Ethanol Burner and Ethanol before burning28.8gFinal Mass of Ethanol Burner with remaining Ethanol after burning28.4gMass of Ethanol that burnt(i) Fill in the missing information in the class table.(1mk)(ii) The 50ml of water used is de-ionised and its specific heat capacity c, is 4.2kJ/Kg/K. Calculate heat of combustion of theethanol used.(2mks)(iii) Calculate the moles of ethanol that were burnt (RMM of ethanol = 46).(2mks)(iv) Calculate the heat of combustion per mole of ethanol.(2mks)4.(a) Describe the chemical test that can be used to distinguish sodium sulphate from sodium sulphite.(2mks)(b) Starting with lead oxide, describe how a pure sample of lead carbonate can be prepared in the laboratory.(3mks)Page | 6300Chemistry paper 1, 2&3 (i) What is solubility?(1mk)(ii) The table below shows the solubility of solids X and Y at different temperatures.SOLUBILITY IN g PER 100g OF WATERTEMPERATURE (0C)XY68.0112.065.058.074.055.053.058.048.047.047.045.043.036.043.0I) Draw the solubility curves on the same axes. (Temperature on the X-axis).(1mk)II) A solution of 68.00C contains80g of solid X and 80g of solid Y. The mixture is cooled to 53.00C. Using the graph you havedrawn in I) above, give the composition of the solid formed.(2mks)5.(a) A, B, C are three homologous series of organic compounds.SeriesGeneral formulaACnH2n-2BCnH2nCCnH2n+2(i) What is the name given to series C?(1mk)(ii) Write down the name and structural formula of the second member of series “B”.(2mks)(iii) Draw the structural formulae of the first two members of the series ?A?.(2mks)(iv) Complete the balance in the following equation:CH3CH3 + O2→(b) Study the flow chart below and answer the questions that follow.ButaneStep IJStep IIEtheneHPolymerisation Step IIIWater at 3000C and60 atmospheres EthanolStep IVPropanoic acidJ(i) State the conditions for the reaction in step I to occur.(1mk)(ii) Identify substance H.(1mk)(iii) Give:-(I) One disadvantage of the continued use of substances such as J.(1mk)(II) The name of the process that takes place in step III.(1mk)(III) The name and the formula of substance K.(2mks)Name:…………………………………………………………Formula:………………………………………………………(iv) The relative molecular mass of J is 16,800. Calculate the number of monomers that make up J.(2mks)6.(a) The first step in the industrial manufacture of nitric acid is the catalytic oxidation of ammonia gas.(i) What is the name of the catalyst used?(1mk)(ii) Write the equation for the catalytic oxidation of ammonia gas.(1mk)(iii) Nitric acid is used to make ammonia nitrate. State two uses of ammonium nitrate. (1mk)(b) Study the apparatus and answer the questions that follow.Page | 64Chemistry paper 1, 2&3 (i) Why does nitric (v) acid appear yellow?(1mk)(ii) Give the identity of gas Q and give its test.(1mk)(iii) State the use of glass wool and the role of sand in the experiment.(2mks)(iv) Write an equation to show the decomposition of nitric acid when strongly heated.(1mk)(c) Determine the oxidation of nitrogen in NO-3.(1mk)7.In the laboratory small quantities of oxygen gas can be generated using the following set-up. Study it and answer thequestions that follow.(a)(i)Give the name of substance R.(1mk)(ii)What is the purpose of the apparatus labeled S?(1mk)(iii)Write an equation for the reaction taking place in the round bottom flask.(1mk)(b) Sodium peroxide react with water at room temperature to produce 0.4dm3 of oxygen gas. Determine the mass of sodiumperoxide which was reacted with water.(Molar gas at r.t.p = 24.0 dm3, Na = 23, O = 16, H = 1)(2mks)(c) A burning piece of magnesium ribbon continues to burn in a gas jar containing carbon (IV) oxide. Explain.(2mks)(d) State two commercial uses of oxygen gas.(1mk)Page | 65Chemistry paper 1, 2&3 NANDI NORTH AND NANDI CENTRAL JOINT EXAMINATIONS 2016 233/3 CHEMISTRY PRACTICALS CONFIDENTIAL INSTRUCTIONS TO SCHOOLS In addition to the apparatus and fittings found in a chemistry laboratory, each candidate will require the following: -1.About 120cm3 of solution Q - 2M hydrochloric acid.2.About 120cm3 of solution R - 2M sodium hydroxide.3.2g piece dustless chalk (STRICTLY OMEGA TYPE). Cut a piece which must weigh 2g and label it solid S.4.Stop watch / clock.5.1 pipette.6.1 burette.7.3 250ml conical flaks.8.1 measuring cylinder (100ml)9.1 measuring cylinder (10ml)10.5 test tubes11.1 filter paper12.Filter funnel13.1 dropper14.250cm3 distilled water.15.Solid F - Barium nitrate solid.16.Distilled water.17.Blue and Red litmus paper.18.Wooden splint.19.10ml measuring cylinder.20.Boiling tube.21.8 clean test tubes.22.Solid sodium hydrogen carbonate.23.A small piece of aluminium foil.24.Test-tube holder.25.Solid G - maleic acid.Each student should have access to:-?Source of heat.?Acidified potassium manganate (VII) with a dropper.?Acidified potassium dichromate (VI) with a dropper.?0.5M Lead (II) nitrate with a dropper.?0.5M Barium nitrate with a dropper.?2M sodium hydroxide with a dropper.?2M ammonium solution with a dropper.Page | 66Chemistry paper 1, 2&3 NANDI NORTH AND NANDI CENTRAL JOINT EXAMINATIONS 2016 233/3 CHEMISTRY PAPER 3 PRACTICAL JULY / AUGUST 2016 TIME: 2 ? HOURS 1. You are provided with:-? Solution Q, a 2M solution of Hydrochloric acid. ? Solution R, a 2M solution of Sodium hydroxide. ? Solid S, 2g piece of chalk (impure calcium carbonate) You are required to determine: (i) How the rate of reaction between carbonate varies with concentration of hydrochloric acid. (ii) Determine the percentage purity of the carbonate. Procedure I (a) Measure 10cm3 of solution R into a 100cm3 measuring cylinder. Add distilled water to make 100cm3 of solution. Transfer the solution into a 250ml conical flask. Label it solution T. Fill the burette with solution T. (b)Label 5 test tubes 1, 2, 3, 4 and 5.(c)Using a dropper and a 10ml measuring cylinder, measure 1cm3 of solution Q into test tube 1.(d)Measure 100cm3 of solution Q into a 250ml conical flask. Transfer solid S into the conical flask and immediately start astop watch.(e)Swirl the remaining mixture for a further 1 minute. Using a dropper and 10ml measuring cylinder draw out 1cm 3 of themixture into test tube 2.(f)Swirl the remaining mixture for a further 1 minute, draw 1cm3 of mixture into test tube 3.(g)Repeat procedure (f) above and place the mixture in test tubes 4 and 5.(h) To each of the test tubes 1-5, add 10cm3 of distilled water. transfer contents of test tube 1 into a conical flask. Add 2-3 drops of phenolphthalein indicator. Titrate this solution against solution T in the burette by adding T dropwise till a permanent pink colour just appear. Record the volume of T in the table 1, repeat the procedure with contents of test tubes 2, 3, 4 and 5. Complete the table 1 below. (RETAIN THE REACTING MIXTURE FOR USE IN PROCEDURE II) TABLE I Test Tube Number12345Time (minutes)01234Final burette reading (cm3) Initial burette reading (cm3) Volume of solution T used (cm3) (6mks) (a)On the grid provided, plot a graph of volume of solution T(y-axis) against time.(3mks)(b)(i) From the graph, determine the volume of solution T that react with 1cm3 of the mixture after 3? minutes.(1mk)(ii) Calculate the concentration of the mixture after 3? minutes.(1mk)(c) In terms of rate of reaction explain the shape of the graph.(1mk)Procedure II Filter solution S obtained in procedure 1 above into a clean conical flask. Pipette 25cm3 of this solution into a clean conical flask. Add 20cm3 of distilled water. Rinse the burette and fill with fresh solution T. Titrate using 2-3 drops phenolphthalein indicator. Record your results in the table II. Repeat the procedure two more times and complete the table II below. Table II IIIIIIFinal burette reading (cm3) Initial burette reading (cm3) Volume of solution T used cm3 (4mks) (a) Calculate the volume of solution T used.(1mk)(b) Calculate:-(i)The number of moles of the excess acid in 25cm3 of solution Q.(1mk)(ii)The number of moles of the excess acid in 100cm3 of solution Q.(1mk)(c) Calculate the mass of carbonate that reacted with 100cm3 of solution Q.(1mk)(d) Calculate the percentage purity of the carbonate in solid S.(1mk)Page | 67Chemistry paper 1, 2&3 2.You are provided with solid F to carry out the tests indicated below and record your observation and inferences in the spacesprovided.(a) Place a spatula end-full of F in a boiling tube. Add about 10cm3 of distilled water and shake to dissolve.(Retain theremaining solid F for use in test (b) below).Divide the resultant mixture into four portions.(i)To the first portion, add 1cm3 nitric acid followed by 3 drops of Barium Nitrate solution.ObservationInference(1mk)(1mk)(ii)To the second portion, add 1cm3 nitric acid followed by 3 drops of Lead (II) nitrate solution.ObservationInference(1mk)(1mk)(iii)To the third portion, add aqueous ammonia dropwise until in excess.ObservationInference(1mk)(1mk)(iv)To the fourth portion, add sodium hydroxide dropwise until in excess.Retain the mixture for use in part (v) below.ObservationInferences(1mk)(1mk)(v)To the mixture from (iv) above, add a piece of Aluminium foil and warm the mixture gently and carefully.ObservationInferences(2mks)(1mk)(i)Using a clean metallic spatula, place a little of the remaining solid F and burn it strongly on a non-luminous flame.ObservationInferences(?mk)(?mk)3.You are provided with substance G. Carry out the following tests and record your observations and inferences in the spacesprovided.(a) Place a spatula end-full of solid G on a clean metallic spatula and ignite.ObservationInference(1mk)(1mk)(b) Put the remaining solid G in a clean boiling tube and add about 10cm3 of distilled water divide the solution into fourportions.(i) To the first portion add two drops of acidified potassium manganate (VII).ObservationInference(? mk)(1mk)(ii)To the second portion, add 3 - 4 drops of acidified dichromate (VI).ObservationInferences(? mk)(1mk)(iii)To the third portion, add a half spatula end-full of sodium hydrogen carbonate.ObservationInferences(1mk)(1mk)(iv)To the fourth portion, test the PH with universal indicator.ObservationInferences(1mk)(1mk)Page | 6800Chemistry paper 1, 2&3 NANDI NORTH AND NANDI CENTRAL JOINT EXAMINATIONS 2016 233/1 CHEMISTRY PAPER 1 MARKING SCHEME1.2.(a) B -Group VI√?Period 2√?(b)A2B3√1(a) The volume of a fixed mass of a gas is directly proportional to absolute temperature at constant pressure (WTTE). (b) V 1 ? V 2T1T 24 8 ? 10298? 2? 2? 3 2 ? 10T2? 1 32?10?298T2?? 1984 8 ? 10671 kor ?? 274 333 0 C 3.(a)(Polyphenyl ethane)(b) HHC=CH 4.Brown solution√? produce; Equilibrium√? shift to the left so as to reduce√1 the amount of HCl added.5.(a) i) Concentrated hydrochloric acid. √1ii) Concentrated sulphuric (VI) acid. √1 (b) i) The delivery tubes in the wash bottles with the drying agent are arranged the other way round. (opposite) √1 - conical flask not stoppered. ii) Chlorine should be collected by downward delivery√ - denser than air. iii) The tube taking the gas from the conical flask dips into the reactants. √ 6.In C calcium hydroxide react with carbon (IV) oxide to form calcium carbonate which dissolves in excess to re-introduceCa2+ making water hard in D all the Ca2+ are removed by converting it to calcium carbonate thus water is soft.7.(i) Black precipitate of ZnS is formed.- Yellow solid of sulphur is deposited at the bottom of the beaker.(ii) In the fume chamber because H2S is poisonous.8.(a) Drying the gas is necessary to ascertain that the product was a result of igniting hydrogen.(b)(i) Give time to expel all air that was initially in the combustion tube.(ii) Air balloons, hydrogenation, arch welding.9.(i) Amphoteric oxide;(ii) Lead oxide rej. formula/Zinc oxideAluminium oxide.10.(a) To remove an oxide layer that had developed for a long time with exposure to oxygen.(b) TSVU.11.Gas G is diffusing faster than air in the beaker.Gas H is denser than air therefore diffuses at a lower rate than water. 12. Beans contain three types of amino acids. 13.Add PbCO3;with HNO3;Pb(NO3)2(aq) is formed.Add Pb(NO3)2 with a soluble chloride or dilute HCl; PbCl2 + a soluble NO3- formed. Filter; PbCl2(s) collected as a residue;dry between filter papers or in the oven.14.(a)- Magnesium continued burning.- A white solid is formed.- Hot magnesium dissociates N2O into N2 and O2 magnesium then burns in O2.(b) Mg(s) + N2O(g)→ MgO(s) + N2(g)15.(a)2H2(g) + O2(g)2H2O(l)4OH- + 2H2(g)→ H2O+4 =Eθ+ 0.83VO2(g) +2H2O + 4e-→4OH Eθ- 0.403VO2 + H2 →2H2OEθ- 0.43V10 x 0.43V = 4.3V(b)E.M.F. = 0.40 - 0.83 = 1.23 per cell.Page | 6900Chemistry paper 1, 2&3 For ten cells = 10 x 1.23 = 12.3 (c) Water formed can be used. Water is not a pollutant. Don?t release harmful wastes. 16.(i) P - IIQ - III(ii) Q - Has more delocalized electrons (3e-) than P (2e-)17.(i) White precipitate forms which dissolves to form a colourless solution. This is due to the formation of insoluble calciumcarbonate which dissolves forming calcium hydrogen carbonate.(ii) Any noble gas mentioned / water vapour.18.(a)- Ammonium chloride / NH4Cl(b)- Sublimation19.- Coke - to reduce PbO to Pb- Limestone - to remove silica as slag.- Scrap iron - to reduce unleaded PbS to Pb.20.(a)- Bulb lights- Water turns from colourless from colourless to yellow green.(b)2H+ +2e →H2(g)ΔHpΔHf + ΔH3 = ΔH1 + ΔH221. 3H+2C+O2CH3CH2OHΔH1+3023/2ΔH3DH22CO2+3H2OΔH1=ΔH2 + ΔH3-1646=-277ΔH3=-1646 + 277=-1369kJmol-122.(a)(I) Silk remained coloured(II) The silk cloth was bleached.(b) SO2(g) + H2O(l) H2SO3(aq)H2SO3(aq) + [O]dye→ H2SO4(aq) + colourless material23.(I) C3H8+ 5O2(g)→ 3CO2(g) + 4H2O(g)ΔH3 = ΔH1 + ΔH2 - ΔHf= 2x - 394 + 3x - 286 - 277 -788 - 858 + 277=-1646 + 277-1369kJmol-1 (II) Carbon (IV) oxide which is acidic dissolves in the condensed water and forms carbonic acid whose PH is less than 7. 24.(a)(i) A(ii) B25.1 mole CaCO3 2 moles of HCl (CaCO3(s) + 2HCl(aq)→ CaCl2+H2O(l)+CO2(g) )Therefore 0.1 ( ?) mole CaCO3 0.2 mole (?)CaCO3 = 40 + 12 + 48 = 100g ( ?)Therefore 15g CaCO3=15=0.15 molesOr 100g →2 moles100g?←0.2 molesExcess moles 0.15 - 0.05 ( ?)0.2 x 100 = 10gExcess mass = (0.05) x 100 ( ?) = 5g2Excess = 15g - 10g = 5g26.(a) Gas syringe / graduated gas cylinder / measuring cylinder.(b)(i)25 20at 370151050306090120150180Time (s)Page | 7000Chemistry paper 1, 2&3 (ii) The molecules of the reactants have higher energy hence higher number of molecules with enough activation energy (En). The reaction is faster / are more effective collusions (more fruitful collissions.27.(a)- For visibility - Non reactive.- Does not corrode - Heat resistant (any 2 correct((b)- Desicator- Use drying or keeping substances free of moisture.- Evaporating dishUse evaporating liquids to obtain crystals.28.H3O+ - had donated a proton or proton donor.29.(a)- Good for drinking contain calcium which help to form strong teeth and bones.- Prevent lead poisoning.- Brewing beer.(b)- When hard water is passed through sodium permutit, sodium ions are replaced with Ca2+ and Mg2+ making water softsince ions responsible for water hardness have been removed.30.(a)- Time taken for a given mass of radioactive isotope to reduce to half.(Time taken for activity to realize by ? the original amount)(b)- No of half lives = 4t?t?t?t?804020105gInitial mass = 80gOR?1?TM ?? 2?? t? M 112 ? ?1? ?100?5?2?25?1?M?0 ? 16? ? 5? M0?16?5?80gPage | 71Chemistry paper 1, 2&3 NANDI NORTH AND NANDI CENTRAL JOINT EXAMINATIONS 2016 233/2 CHEMISTRY PAPER 2 MARKING SCHEME 1.(a) Transition elements√1 // Transmission metals(b) Y + e→ Y-√?(c) - The atomic radius is larger√1 than the ionic radius because the outermost√1 energy level is destroyed as the atom forms the ion // The atomic radius is larger because atom has more energy levels than ion. (d) The outermost electron in V is loosely√1 held because of the large atom but in D it is strongly√1 held because of smaller atom // small size. (e) Alkaline Earth metals. √1(f)2: 8 : 3 √1(g) i) Giant Ionic structureii)- It is soluble in water //√1- It has high melting point √1(h) TY2√1(i) Increases because of increase in number of free mobile electrons on the outermost energy level.2.(a)(i)Brine is a concentrated√1 solution of sodium chloride.(ii)Na+√?H+√?(iii) Ion - Cl-√1Factor of discharge - concentration √1(b)(i) On the diagram(ii)- To complete circuit. √1- To provide for a balance of charges in the two half cells. √1(iii) Fe(s)→ Fe2+(aq) + 2eEcell=+ 0.44VH+/H(iv) Ecell=0.0 - - 0.44=+0.44V√1(v) Fe / Fe2+ // H+ / HEcell=+ 0.44V3.(a)(i) Latent heat of fusion. √1(ii) Liquid(iii) Because heat supplied is used to change state from liquid to gas.(iv)2(b)(i)51.5k;0.4g(ii) ΔH=50 x 4.2 x 51.5=-10.815kJ1000(iii) Moles=0.446=0.0087 moles(iv)-10.815 = 1243/1kJ/mole0.00874.(a)- Add water to the two salts separately√?Precipitate which dissolves confirms salt was Na2SO4√?- Shake to dissolve√?Precipitate which does not dissolve is Na2SO4√?- Add lead (II) nitrate√? - Add dilute HNO3 or HCl√? (b) - Into a beaker containing dilute nitric acid, √? add lead oxide until in excess. - Filter to remove excess lead (II) oxide√? as residue and lead (II) nitrate as filtrate. - To filtrate add Na2CO3 solution. √? - Filter√? to remove PbCO3 as residue and sodium nitrate as filtrate. - Wash√? residue and dry. √? (c)(i) Solubility is the mass (in grams) of solute that is dissolved in 100g of solvent at a certain temperature.(ii)(I) THE GRAPH(II)X - 80 - 58 = 22g of XY - 80 - 48 = 32g of X5.(a) (i) Alkanes√1(ii) Propene√1 (CH3CH = CH2) √1(iii) HC = CH√1 CH3C = CH√1EthynePropyne(iv)2CH3CH3(g) + 7O2(g)→4CO2(g) + 6H2O(l) √1(b)(i) Temperature = 4000C, √? Pressure = 1.5atm√?(ii)Ethane / CH3CH3√1Page | 72Chemistry paper 1, 2&3 (iii) I. It is non-biodegradable. √1 II. Oxidation√1 III. Name - Ethylpropanoate√1 Formula - CH3CH2COO CH2CH3√1 (iv)(CH2 = CH3)n = 16,800√128n=16,800√?n=600 monomers √?6.(a)(i) Platinised rhodium / gauze. √1(ii)4NH3(g) + 5O2(g)→4NO(g) + 6H2O(l) √1(iii)- Nitrogenous fertilizers√?- Make explosives√?(b)(i)Due to presence of Nitrogen (IV) oxde. √1(ii)Oxygen gas. It rekindles a glowing splint.(iii)- Glass wool is to soak Nitric (V) acid. √1- It conducts heat from the acid. √1- Sand prevents direct heating of acid which might explode. √1(iv)4HNOH3(aq) →4NO2(g) + 2H2O(l) + O2(g)(c) Let O.N be Xx = 6 - 1Oxidation numberx - 6 = -1x = +5of Nitrogen is +57.(a)(i) Manganese (IV) Oxide. √1(ii)- To support the gas jar in position for collection of gas. √1- To allow the gas generated into the gas jar.(iii)MnO2H2O2(l)2H2O(l) + O2(g) √1(b)2Na2O2(s) + 2H2O(l) →4NaOH(aq) + O2(g)0.4dm3=0.011666√?Mass of Na2O2= 0.03332 x 78√?24dm3=2.59896√?Moles of Na2O2=2 x 0.01666 moles√?=2.6g√?=0.03332 moles(c) Heat produced decomposes√1 Carbon (IV) oxide to carbon and oxygen. The oxygen√? produced supports thecontinuous burning of magnesium.(d)- Air enriched with oxygen is used by patients with breathing difficulties.- When mixed with helium it is used by mountain climbers and deep sea divers.- Oxygen mixed with acetylene burns to produce a hot flame used for welding and cutting metals.- Used to remove impurities during steel making.(any 2 - ? mark each)Page | 7300Chemistry paper 1, 2&3 NANDI NORTH AND NANDI CENTRAL JOINT EXAMINATIONS 2016 233/3 CHEMISTRY PAPER 3 MARKING SCHEME 1.(a)Table 1(6mks)t Tube Number12345e (minutes)01234al burette reading (cm3)10.018.927.235.243.0ial burette reading (cm3)0.010.018.927.235.2lume of solution T used (cm3)10.08.98.38.07.8Complete table………………… (3mks)Conditions and penalties-Penalize ? mark for any space unfilled to maximum of 3mks.-Where volume of T is constant, mark the first reading and reject the rest.-Penalize ? mark for any titre reading beyond 12cm3(b) Decimal ……………………….(1mk)-Award 1 mark for 1 or 2 decimal places used consistently, otherwise penalize FULLY for inconsistent use of decimals oruse of whole numbers.(c) Accuracy ……………………… (1mk) -Award 1mk if the candidate?s first reading is within +0.2 of S.V, otherwise penalize FULLY.(d) Trend …………………………. (1mk)-Award 1mk for continuous decrease in the volume of solution T, otherwise penalize FULLY.(a) GRAPH(i) Labeling ……………….. (? mk)-Penalize fully for inverted axis or use of wrong units on axes.-Ignore if no units are given and credit accordingly.(ii) Scale …………………. (? mk)-Plots must cover at least half of the grid.-Scale interval must be consistent.-Scale must accommodate all points on table whether plotted or not.(iii) Plotting …………………(1 mk)-Mark correct plots that are within the correct scale interval.-Award 1m for 4 - 5 plots given; ? mk for 3 plots; O if 2 plots are given.(iv) Curve …………………. (1mk)Award 1mk for smooth curve, otherwise award zero.(b)(i) Award ? mark for showing on the graph and another ?mk for the correct value.(ii) Molarity of NaOH, solution TM1V1=M2V22 x 10=M2 x 100M2 = 0.2 Mass of T=(0.2 x correct ans b(ii) √?1000 =correct answer√?Moles of HCl in 1cm3 = correct answer. ? 1000cm3 →(100 x Ans) √?1cm3 = Correct answer √? (c) Rate of reaction decrease with decrease√1 in concentration of hydrochloric acid (WTTE) Procedure II Table II periment numberIIIIIIal burette reading (cm3)112ial burette reading (cm3)1lume of solution T used cm3102Table II ……………………………. (4mks)(a) Complete table ……………………..(1mk)Penalize ? mark once for inverted able, incomplete table, unrealistic values, arithmetic error or values beyond 50cm3 andunexplained.(b) Decimals …………………. ( ? mark)Penalize FULLY for inconsistent use of decimals or no decimals used.Page | 7400Chemistry paper 1, 2&3 (c) Accuracy ………………… ( ? mark) Compare the candidates value with S.V If within +0.1 award ? mark If not within +0.1 award (0mark) (d) Principles of averaging ………………….. (1mk) - Award 1mk for 3 consistent values averaged. - Award 1mk if 3 experiments done but 2 are consistent and are averaged. - Award zero mark if 3 values are consistent and only 2 are averaged. - Award zero mark if inconsistent values are averaged. (e) Final accuracy ………………………………. (1mk) The candidate?s correctly averaged value is compared to S.V. If within +0.1 award 1mk If within +0.2 award ? mark If beyond +0.2 award 0 marks Calculations(b)(i) Moles of solution T used==Moles of HCl in 25cm3Moles of ratios 1:1=(ii)Moles of HCl in 100cm3 = ? 100=(c)Mass of carbonateMoles of carbonate==Mass==(e)% of purity=2.(i)Observation? 0 2 ? Av titre ?1000correct answercorrect answer? A ns( i )?25correct answer? x answer b(i)correct answer100 x correct answer abovecorrect answer(Ans C x 100)=Correct answer2Inferences2? 2? 2?No white precipitateSO4,CO3,SOabsent3Reject:-No observable change-No change-No ppt-No colour change-No observation(1mk)(ii)ObservationNo white precipitate1 mk for all mentioned correctly? mk for two mentioned correctly0 mk for one mentioned correctly.(1mk)Inferences2? 2? ? 2? absentReject:-No observable change-No change-No ppt-No colour change-No observation(iii)S O 4, C O 3, C la n d S O 3(1mk)(1mk) ObservationInferences-White precipitate insoluble inexcess2?2?Mg,BapresentNH3(aq)Accept for ? mark(1mk)2?3?2?(iv)Observation-White precipitate insoluble inZn, Al, PbInferencesexcess2? 2?absent(1mk)NaOH(1mk)Mg, BapresentAccept for ? mark2? 3? 2? Zn,Al,Pbabsent(1mk)Page | 7500Chemistry paper 1, 2&3 (v) ObservationInferences-Effervescence // bubbles of a colourless gas?are produced which turn red litmus paperblue.(2mks)(b)NO 3NH 3presentgas(1mk) ObservationInferencesBurns with yellow-green flame.2?Reject- Green- Yellow( ? mk)Baions present(? mk)3.(a)ObservationMelts; colorless liquid formsBurns with smoky / sooty yellow flame.Accept for ? mark- Yellow / luminous flame(1mk)(b)(i)ObservationKMnO 4 decolourised or KMnO 4 purple colourof turns colourless.Reject-Turns colourless-Solution turns colourless-Forms colourless solution-DecolourizedInferencesC = C or- C = C -Long chain organic compoundUnsaturated organic compound presentRejectLong chain hydrocarbon alkyne, alkene (1mk)InferencesC = C or- C = C - or R-OH(1mk) (1mk)(ii)ObservationInferencesOrange KCr Odoes not turn green/ orangeR - OH absent 227colour ofKCrOpersists / retained / does not227(1mk)change.(1mk)NB:- Penalize fully for any contradictory functional group- Penalize fully for wrong observation recorded but correct inference.(iii)ObservationInferencesEffervescence / bubbling / fizzing or??H/ HColourless gas is produced that puts off burning3 O/ RCOOH or -COOH present, splint.? mk for any mentioned.Reject( ? mark)Hissing / Fizzling(1mk)(iv)ObservationInferencespH4Weakly acidic( ? mark)( ? mark)Page | 7600Chemistry paper 1, 2&3 KASSU JOINT EVALUATION EXAMINATION Kenya Certificate of Secondary Education 233/1 CHEMISTRY Paper 1 THEORY JUNE 2016 Time: 2 hours 1.(a) Give two differences between luminous and non-luminous flames.(2 marks)(b) How is the non-luminous flame produced?(1 mark)2.(a) The apparatus below were used to separate a mixture of liquid A and B.A B State two properties of liquids that make it possible to separate using such apparatus.(2 marks)(b) Give the name of the above apparatus.(1 mark)3.(a) Explain why solid Carbon (IV) oxide is preferred over ordinary ice for use by ice cream venders.(1 mark)(b) Name one piece apparatus used to measure volume of gases.(1 mark)(c) Draw a diagram of a deflagrating spoon.(1 mark)4. The table below shows the pH values of solutions P, R, Q and S.SolutionPRQSpH276.513.5(a) Which solution represent:(i)Strong base-(1 mark)(ii)Weak acid-(1 mark)(b) Give an example of solution S.(1 mark)5.6.95g of hydrated iron (II) sulphate FeSO4. nH2O was dissolved in 250 cm3 solution resulting into a 0.1M solution.Determine the value of n. (Fe = 56, O = 16, S = 32, H = 1).(3 marks)6.Rusting leads to fast wearing out of farm tools and equipment as well as buildings.(a)Give the chemical name of rust.(1 mark)(b)What two conditions accelerate rusting process?(2 marks)7. Study the diagram below and answer the questions that follow. Glass wool soaked in water Iron Gas Heat (a) Write an equation for the reaction that take place in the combustion tube.(1 mark)(b) Why would it not be advisable to use potassium in place of iron in the set-up?(1 mark)(c) Glass wool should be heated before heating iron. Explain.(1 mark)8.I.Name the following organic compounds.(a)CH3 CH CH2 CH CH3(1 mark)CH3 Br(b)HOCH2 - CHOH - CH2OH(1 mark)II.GivenA CH3(CH2)16 COO- Na+B CH3(CH2)6 CH(CH3)CH2 SO-3 Na+Identify detergent A and B(2 marks)Page | 7700Chemistry paper 1, 2&3 9.In terms of structure and bonding, explain the following.(a) Graphite is used as a lubricant.(1 mark(b) Alluminium is better conductor of electricity then magnesium.1 mark)(c) Water is a liquid at room temperature while hydrogen sulphide is a gas.(1 mark)10.(a) Define the term molar latent heat of fusion.(1 mark)(b) The molar heat of fusion of ice at O0C is 6kJ mol-1. Calculate the heat change when 36g of ice is converted to 36g ofwater at 100C. (SHC = 4.2-1g K-1, density = 1.0g/cm3, H = 1.0, O = 16.0)11. Draw a well labeled diagram showing how blister copper is purified.(3 marks)12. Gas Q with a relative molecular mass of 48 took 50 seconds to diffuse through a porous diaphragm. How long will it take forthe same amount of hydrogen Chloride (HCl) to diffuse through the same diaphragm under similar conditions?(H = 1.0, Cl = 35.5).(3 marks)13.(a) Calculate the oxidation state of chromium in the ion Cr2 O2-.(1 mark)(b) Using oxidation numbers, determine from the equation below the species which undergoes oxidation and reduction.2FeCl2(aq)+ Cl2(g)2Fe Cl3(aq)Oxidation-(1 mark)Reduction-(1 mark)14. Given elements A, B and C with atomic numbers 11, 19 and 13 respectively.(a) Compare the atomic radius of A and C. Explain.(2 marks)(b) Compare reactivity of A and B.(1 mark)15. Haber process (the manufacture of ammonia gas) is given by the following equation.N2(g) + 3H2(g)2NH3(g)ΔH = -92kJ mol-1.State and explain the effect of:(a) Introducing some drops of water to the equilibrium.(1 mark)(b) Pumping nitrogen gas to the equilibrium mixture.(1 mark)(c) Lowering the temperature of the reaction.(1 mark)16. Elements P and Q have the following atomic numbers 19 and 8 respectively. (i) Using dot () and cross draw a diagram to show how the elements form bonds.(1 mark)17. Describe how sodium sulphate crystals can be prepared starting with 50cm3 of 2M sodium hydroxide and 1M sulphuric(VI) acid.(3 marks)18. Write ionic equations to show how;(a)(i) Excess ammonia solution reacts with a solution containing Copper II ions.(1 mark)(ii) Excess sodium hydroxide added to a solution containing Al3+ ions.(1 mark)(b) Give the name of the following ion [Zn(NH3)4]2+(1 mark)19.(a) Define electrolysis.(1 mark)(b) During the electrolysis of molten aluminium oxide, write the equations at the;Anode-(1 mark)Cathode -(1 mark)20.(a) Give any two differences between alpha and beta particles.(2 marks)(b) A radioactive isotope T decays by emitting three alpha particles to formwhat is the atomic number and massnumber T?Atomic number-(1 mark)Mass number-(1 mark)21.(a) Using acidified potassium dichromate (VI) solution, describe how you would differentiate between sulphur (IV) oxideand hydrogen sulphide.(2 marks)(b) Identify the catalyst preffered in contact process. Explain.(2 mark)22. Study the following part of the solvay process for the manufacture of sodium carbonatefollows:Ammoniated brineAmmonium chlorideChamberand answer the questions that Step 1INaHCO3(s)Carbon (IV) oxideStep 2Na2CO3(s)(i) State the main source of Carbon (IV) oxide in the process.(1 mark)Page | 78Chemistry paper 1, 2&3 (ii) Write down the overall equation for the reaction in chamber I.(1 mark)(iii) Name process in step 1.(1 mark)23.(a) The following equation involve hydrochloric acid.MnO2(s) + 4HCl(aq)MnCl2(aq) + 2H2O(l) + Cl2(g)State the type of reaction taking place in the reaction.(1 mark)(b) State two contrasting chemical properties of hydrogen and chlorine.(2 marks)24.(a) An element O has two isotopesO containing 90% and IsotopeO.(i) What are isotopes?(1 mark)(ii) Find the R.A.M of O.(2 marks)25.(a) When a hydrocarbon is completely burnt in oxygen 4.2g of Carbon (IV) oxide and 1.71g of water were formed.(a) Determine the empirical formular of the hydrocarbon.(3 marks)(b) Given that formula mass of compound above is 28. Find the molecular formular.(1 mark)26.(a) Name the two types of polymerization.(1 mark)(b) Study the section of the polymer below and answer the questions that follow.HHHHHHCCCCCCHC6H5 C6H5 HHC6H5(i) Give the name of the polymer above.(1 mark)Page | 7900Chemistry paper 1, 2&3 KASSU JOINT EVALUATION TEST CHEMISTRY 233/2 THEORY 2 Hours 1.The grid below shows part of the periodic table. Use it to answer the questions that follow. The letters do not represent actualsymbols.SUVPRTXWQ(a)Which of the elements has the highest atomic radius? Explain.(2 marks)(b)Identify the most reactive Oxidizing agent. Explain.(2 marks)(c)Compare the atomic radius of P and R. Explain(2 marks)(d)Give the formula of one stable ion with an electron arrangement of 2.8 which is:(i)A Negatively charged divalent ion.(2marks)(ii)A Positively charged monovalent.(e)Given that the mass number of W is 40. Write down the composition of its nucleus(2 marks)(f)Write the formula of the compounds formed between.(i) Element R and X.(1 mark)(ii) Give one property of the structure formed when R and X bond.(1 mark)2.An aqueous solution of zinc sulphate is electrolysed using platinum electrodes as shown in the set up below.D.C supply Syringe Syringe X cm3 2 x cm3 Electrode B Electrode A Zinc sulphate solution (a)(i) Write a half equation for the reaction taking place at electrode A.(1mark)(ii) Identify electrodes A and B(2 marks)(iii) State and explain the observation at electrode B if copper plate was used instead of platinum electrode.(2marks)(b) 0.22g of metal Q is deposited by electrolysis when a current of 0.06A flows for 99 minutes.(RAM of Q = 184, 1F = 96500c)(i) Find the number of moles of Q deposited.(1mark)(ii) Determine the value of n in the metallic ion Qn+(3marks)(c) Determine oxidation number of chlorine in ClO3-(1mark)(d) An iron spoon is to be electroplated with silver. Draw a labelled diagram to represent the set-up that could be used to carryoutthis process.(2marks)3.(a)The scheme below was used to prepare a cleansing agent. Study it and answer the questions that follow.(i) What name is given to the type of cleansing agent prepared by the method above?(1mark)(ii) Name one chemical substance added in step II(1mark)(iii) What is the purpose of adding the chemical substance named in a (ii) above?(1mark)Page | 8000Chemistry paper 1, 2&3 (iv) Name any other suitable substance that can be used in step I(1mark)(v) Explain how an aqueous solution of the cleansing agent removes oil during washing(2marks)(b). Study the scheme below and answer the questions that follow.(i) Identify the catalyst used in step I(1mark)(ii) Name the compounds A and B(2 marks)(iii) Give one disadvantage of compound formed in step III(1mark)(iv) Name the reactions taking place at steps: I and IV(1mark)(v) Describe how substance K is converted to ethanol(2marks)4.(a) State the Hess? law.(1 mark)(b) The enthalpies of combustion of calcium, carbon and decomposition of calcium carbonate are indicated below;C (s) + ?O2 (g)→CaO (s): ΔH=-635 kJmol-1C (s) + O2 (g)→CO2 (g) ΔH=-394 kJmol-1Enthalpy of decomposition of CaCO3 = +178 kJmol-1(i) Draw an energy cycle diagram that links the enthalpy of formation of calcium carbonate to enthalpies of combustion ofcalcium, carbon and decomposition of calcium carbonate.(2 marks)(ii) Determine the enthalpy of formation of calcium carbonate.(2 marks)(c) Some average bond energies are given below.BondEnergy in kJ mol-1C - C348C - H414Cl - Cl243C - Cl432H - Cl340Calculate the energy change for the reaction below.(3 mks)C2H6 (g) + Cl2 (g)→ CH3CH2Cl(g) + HCl(g)5.(a) Define the term solubility.(1 mark)(b) In an experiment to determine the solubilities of two salts X and Y at different temperatures, a candidate recorded herobservations as shown below.Temperature (oC)0102030405060708090Solubility of X in14.317.420.725.028.533.340.047.055.064.0g/100 g of H2O Solubility of Y in25.027.530.032.535.037.640.142.445.048.0g/100 g of H2O(a) On the same axes plot the solubility curves of X and Y.(4 marks)(b) From your graph to determine;(i) The solubility of X and Y at 47 oCSolubility of X(1 mark)Solubility of Y(1 mark)(ii) The temperature at which the two salts are soluble in water.(1 mark)Page | 8100Chemistry paper 1, 2&3 (c) If 60g of X is dissolved in 100 g of water and heated to 90oC, calculate the amount of salt that crystallized out if cooled to 20 oC.(1 mark)(d) State what would happen if a mixture salt X in 100 g of water and 30 g of Y in 100 g of water were cooled from 90 oC to 70oC.(3 marks)(e) State one application of solubility.(1 mark)6.The flow chart below shows some processes in the extraction of zinc. Study it and answer the questions that follow.Zinc blendeCalamineADZinc oxideCZnSO4(aqBEImpure zincDistillationPure Zinc(a) Name the processes represented by A and E.(2 marks)(b) State the reagents required for processes B, C and D.(3marks)(c) Write a chemical equation of the reaction that occurs in process B.(1mark)(d) With an aid of a diagram, explain how you would obtain a pure sample of zinc by process E(3 marks)(e) State two commercial uses of zinc metal.(1 mark)7.The diagram below shows a set-up of apparatus that can be used to prepare nitrogen (IV) oxide. Study it and use it to answerthe questions that followLead(II)nitrate boiling tube Liquid B Gas A Heat icewater(a)(i) Write the equation for the reaction that takes place in the boiling tube.(1 mark)(ii) State the observations made in the boiling tube.(2 marks)(iii) Explain why lead (II) nitrate is preferred over other metal nitrates in this experiment.(1 mark)(iv) Describe how gas A can be identified.(1 mark)(b)(i) Name liquid B(1 mark)(ii) Write a chemical equation to show how liquid B is formed in this experiment.(1mark)(c)(i) In another experiment, excess aqueous lead (II) nitrate solution was reacted with a solution which contained 2.34g ofsodium chloride. Calculate the mass of precipitate formed in this reaction.(Pb = 207, Cl = 35.5, Na = 23)(3 marks)(ii) Write an ionic equation for the reaction that takes place when nitrogen (IV) oxide reacts with aqueous sodium hydroxide.(1 mark) Page | 82Chemistry paper 1, 2&3 KASSU JOINT EVALUATION TEST CHEMISTRY 233/3 THEORY CONFIDENTIALS INSTRUCTIONS TO SCHOOLS In addition to usual provisions and fitting in the science laboratory each candidate is expected to have the following. -One pipette-One burette-One pipette filler-About 100ml of solution M-About 100ml of solution N-Two 250ml conical flask-One boiling tube-10ml measuring cylinders-A stop watch-50ml solution WI-500ml distilled water provided in wash bottle-100ml of 1M dilute hydrochloric acid (WII)-One plane paper-One 100ml glass beaker-About 2.0g of solid P-Metallic spatula-Two filter papers-One filter funnel-Seven dry clean test tubes-One dry boiling tube-Acidified potassium chromate vi solution-Bromine water-Solid F ( maleaic acid about 2g)Access to:-Source or means of heating-2M NaOH supplied with a dropper-2M NH4OH supplied with a dropper-0.2M lead nitrate solution K supplied with a dropper-2M sulphuric cid supplied with a dropper-Dilute nitric v acid-Universal indicator solutionNotes-Solution M is made by accurately weighing 3.95g of potassium Manganate (VII) and dissolving it in 400ml of 1M H2SO4and making up to solution 10, 1litre mark.-Solution N is prepared by dissolving 49.0g ammonium ferrous sulphate, (NH4)2SO4. FeSO4.6H2O and dissolving it in400ml distilled water and making it up to 1litre mark.-Solid P is a mixture of zinc chloride and magnesium carbonate in the ratio of 1;2-Solution K is 0.2M lead nitrate solution.-Substance W1 is prepared by dissolving 40.0g sodium Thiosulphate in 500ml distilled water and making it up to 1.0 litreof solution-Solution (W11) 1M HCl is prepared by dissolving 86ml conc HCl in 600ml distilled water and making solution to 1litremark.Page | 83Chemistry paper 1, 2&3 KASSU JOINT EVALUATION TEST - 2016 233/3 CHEMISTRY PAPER 3 PRACTICAL JUNE 2016 2 ? Hours 1.You are provided with:Solution M containing 3.95g Potassium Manganate (vii), (KMnO4) per litre of solution. Solution N, containing 49.0g of ammonium Ferrous Sulphate (NH4)2SO4. FeSO4.6H2O per litre of solution. You are required to determine the reacting mole ratio of manganate (VII) Ions, MnO4 with Iron (II) ions Fe2+. PROCEDURE: Using and pipette filter transfer 25.0cm3 of solution N into a conical flask. Titrate with solution M in the burette. No indicator is required for this experiment. Record your results in the table below. Repeat the procedure to obtain the accurate volumes. Table I 1st2nd3rdFinal burette readings cm3 Initial burette readings cm3 Volume of solution M used cm3 (4mk) a)Determine the average volume of solution M used.(1mk)b)Calculate:i)The concentration of solution M in moles per litre. (K = 39, Mn = 55, O = 16)(1mk)ii) The number of moles of solution M that reacted with N(2 mks)iii) The concentration in moles per litre of solution N in moles per litre(1mks)(Fe=56, S=32, N=14, H=1)iv) The number of moles of solution N that reacted with solution M in this experiment (2mks)c)Given that 1 mole of solution M gives 1 mole of Mno4- ions and 1 mole of solution N gives 1 mole of Fe2+ ions. Calculate thereaction mole ratio of Fe2+ ions to MnO4- ions(3mks)2.You are provided with:Solution WI - containing 40g of substance Y per litre. Solution WII - 1M hydrochloric acid solution. You are required to investigate experimentally the rate of reaction of Y with hydrochloric acid. Y reacts with hydrogen ions in the hydrochloric acid to give a final yellow precipitate. You will in each experiment measure at room temperature, the time taken to produce a certain amount of precipitate that will make the cross on the white piece of paper just invisible. PROCEDURE On the white piece of paper, make a cross using a pen. Measure 10cm3 of solution WI using a 10cm3 measuring cylinder provided and put into 100cm3 glass beaker provided and place on the cross. The cross should be visible through the solution from a view point directly above the beaker. Using another measuring cylinder transfer 10cm3 of the acid WII to the beaker containing WI and start the stopwatch immediately after the addition. Looking from above the beaker, stop the watch as soon as the cross becomes invisible. Enter the time taken in the table below. Repeat the experiment using the volumes indicated in the table below each time adding appropriate quantity of distilled water to make up the volume to 10cm3 before adding 10cm3 of solution WII. xpt. NoVol. of WI used cm3Vol. of water cm3Vol. of WII cm3Time Seconds11001028210364104461052810(4mks)a) Plot a graph of volume WI against time in seconds (provided graph paper)(3mks)b) From your graph, state how the volume of W I varies with time(1mk)c) What time would 7.0cm3 of W I take to react with 10cm3 of W I I(1mk)d) State two factors which must be kept constant during the experiment(1mks)e) Could the time taken for experiment be shorter or longer if temperature of reacting mixture was at (i) 500C? Sketch a graphon the same axis that would appear for this experiment.(3 mks)Page | 84Chemistry paper 1, 2&3 3. You are provided with solid F. Carry out the tests below. Record your observations and inferences in the spaces provided. a) Place about half of solid F on a metallic spatula and burnt it using a non-luminous flame Observationsinferences(1mk)(1mk)b) Place the remaining solid F in a clean boiling tube and add about 10cm3 of water and shake thoroughly.i)To about 2cm3 of the solution F, put the universal indicator solution provided.Observationsinferences(? mk)(? mk)ii)To about 2cm3 of solution F, add 2cm3 of acidified potassium dichromate (VI) and warm to boilingObservationsinferences(1mk)(1mk)iii) To about 2cm3 of solution F, add three drops of bromine waterObservationsinferences(1 mk)(1mk)You are provided with solid P. Carry out the tests below and record your results in the table.1.(i)Place all solid P in a boiling tube. Add about 10 cm3 of distilled water and shakevigorously, filter and keep both the residue and filtrate.ObservationsInferences( ? mk)( ? mk)(ii)To about 2 cm3 of the filtrate add sodium hydroxide dropwise till in excess.ObservationsInferences( ? mk)( ? mk)2.(a)(i)To about 2 cm3 of the filtrate add ammonia solution till in excess.ObservationsInferences( ? mk)( ? mk)(ii)To about 2 cm3 of the filtrate add four drops of solution K (lead (II) Nitrate)ObservationsInferences( ? mk)( ? mk)(b)Carefully transfer the residue into a test tube and add 5 cm3 of dilute niric (V) acid.(i)To about 2 cm3 of the solution add a few drops of dilute sulphuric (VI) acid.ObservationsInferences( ? mk)( ? mk)(ii)T o about 2 cm3 of the solution add ammonia solution drop wise till in excess.ObservationsInferences( ? mk)( ? mk)Page | 85Chemistry paper 1, 2&3 KASSU JOINT EVALUATION EXAMINATION Kenya Certificate of Secondary Education CHEMISTRY Paper 1 Marking schemes 1.(a)Give two differences between luminous and non-luminous flames.(2 marks)LuminousNon-luminous- Bright yellow flame- Blue flame- Sooty- Non-sooty-4-regions-3-region- Large and wavy- Short and steady(b)How is the non-luminous flame produced?(1 mark)-When the air hole is fully open.2.(a)-Immiscible-Different densities(b)-Separating funnel3.(a)-Better coolant-Sublims leaving no wetness(b)-Syringe(c)4.(a)(i)Strong base-S(1 mark)(ii)Weak acid-Q(1 mark)(b)-Sodium hydroxide/potassium hydroxide5.Moles of solnIf 0.1 moles are in 1000cm3?250cm3=0.025 molesIf 0.025 moles are in 6.95g 1 mole are in ? =278FeSO4 . n H2O = 278 56 + 32 + 64 + 18n = 278 18n= 126 n = 7 6.(a)-Hydrated Iron (III) oxide(b)-High temperatures-Acidic conditions-Salty conditions7.(a)-3Fe(s)+ 4H2O(g) →Fe3O4(s)+ 4H2(g)(b)-It is more reactive, hence reacts explosively with steam.(c)-So as to generate/evolve steam first8.I.(a)2-bromo-4-methyl pentane(b)Propen-1, 2, 3 - trio1II.A-Soapy(1 mark)B-Soapless(1 mark)9.(a)-The hexagonal layers are joined by weak van der wals forces which can slide over each other easily isthe giant cordent structure.(b)-Has more delocalized electrons in their giant metallic structure.(c)-Water has strong hydrogen bonds as compared to the weak van der wals forces in H2S in theirmolecular structure.Page | 8600Chemistry paper 1, 2&3 10. (a)-Molar latent heat of fusion of a substance is the amount of heat absorbed when one mole of the solid is converted into the liquid state at constanttemperature and pressure.(b)RMM of ice (H2O(s)) = (1 x 2) + (16 x 1) = 1818g of ice→6kJ36g of ice→?= 12kJ Heat change in raising water from ΔH = M?ΔT ΔH == 1.512kJ.Total heat change will be: 12.000 1.512 13.512 11.Draw a well labeled diagram showing how blister copper is purified.(3 marks)+-BlistercopperTHCl√RMM of HClPure thin of strip ofcopperCu2+(aq)12. =TQTHCl50()T2HCl==√RMM of Q√36.5√48= T HCl = √T HCl = 43.60 seconds13.(a)2cr + -2 x 7 = -22cr- 14 = -22cr = +12Cr= +6(b)Oxidation-Fe2+ (Iron (II) ions)(1 mark)Reduction-Chlorine(1 mark)14.(a)-C is smaller than A. It has more protons which increases nuclear attraction.(b)-B is more reactive than A.15.(a)-The equilibrium shifts to the right to replace the ammonia gas absorbed by water molecules.(b)-The equilibrium shifts to the right to use up the nitrogen gas added.(c)-Forward reaction if exothermic hence favoured by low temperatures.Therefore the equilibrium shifts to the right.Page | 8700Chemistry paper 1, 2&316.(i)17.----18.(a)(b)-19.(a)(b)20.(a)(b)+222 P+Q2+Moles of NaOH = 0.1 moles2NaOH(aq) + H2SO4(aq)→ Na2SO4(aq) + 2 H2O(l)Moles of H2SO4 required== 0.05 molesVolume of H2SO4 required= 0.05 = x=50cm3Measure 50cm3 of 1M H2SO4 and add it to 50cm3 of 2M NaOH(aq) in a beaker. Heat the mixture to concentrate the solution.Allow the concentrated solution to evaporate slowly to form crystals of sodium sulphate. (i) Cu(OH)2(s) + 4NH3(aq) → [Cu(NH3)4]2+(aq) + 2OH-(aq)(ii)Al(OH)3(s) + OH-(aq)→ [Al(OH)4]-(aq)Tetramine zinc ions.Process of the decomposition of an electrolyte by passing electric current through it.Anode -6O2-(l)→ 3O2(g) + 12e-(1 mark)Cathode -4Al3+ + 12e-→ 4Al(s).(1 mark)AlphaBetaPositively chargedVery chargedHeavyLightAtomic number -89(1 mark)Mass number-226(1 mark)(1 mark)21.22.23.24.(a)(b)(i)(ii)(iii)(b)(a)Bubble the gases into separate test tube containing acidified potassium dichromate (VI) solution; Both changepotassium dichromate (VI) solution from orange to green, but a yellow solid overdue/deposited is formed with hydrogen sulphide no yellow deposit formed with sulphur (IV) oxide.-Platinum and vanadium (V) oxide.-Vanadium (V) oxide is preferred because it is cheaper and less easily poisoned.-(Heating) coke/calcium carbonate.NaCl(aq) + NH3(g) + H2O(l) + CO2(g) → NaHCO3(s) + NH4Cl(aq)-Cooling-The reaction is exothermicHydrogenChlorine(i)Reducing agentOxidising agent(ii)Does not bleachBleaching agent(i)-They are atoms of some elements with some atomic number but different mass number due to differentnumber of neutrons.()() (ii)====16.225.(a)Elements CElements HMass= 1.14555= 0.19No. of moles= 0.095= 0.19= 1= 2(b)(CH2)n = 2814n = 28n = 2C2H426.(a)-Addition-Substitution(b)(i)Polyphenylethene/ polyslyrenePage | 8800Chemistry paper 1, 2&3 KASSU JOINT EVALUATION TEST CHEMISTRY 233/2 THEORY 2Hours 1. (a) Q- ??This is because it has the highest number of energy levels. ?? (b) U??- This is because U has the highest nuclear change due to its small atomic radius among the non metals. (c) P has bigger atomic radius than R?. This is because P has higher nuclear charge than R. ?? (d) i)S2-ii) P+ (e) P = 18 N = 40 - 18 = 28 P = 18?? N = 22?? (f)(i)RX2(ii) (a) Compounds with the above structures are soluble in water but insoluble in organic conduct. (b) Compounds with the above structure conduct electricity in molten and aqueous state but they are non conductors in solid state. (c) Compounds with the above structure exist in crystalline form (d) Compounds with the above structure have very high melting and boiling point. 2.(a)(i)2H +(aq)+ 2e - →H2(g)?1(ii) A-AnodeB-cathode(iii) B reduces in size;? 1copper anode dissolves ? 1 Cu(s)→ Cu 2+(aq) + 2e-?(b)(i)Moles of G= 0.22? ? =0.0012mole? ?184(ii) Q = IT =0.06 x 99 x 60 = 356.4C?10.0012mole→356.4C1mole→?1x 356.4 = 297000C?10.00121mole of - e= 96500C?= 297000C297000 ? ? x1 =3.07896500n = +3? ?(c) x+ 3 (-2) =1- ? ?x + -6 -1x = -1+6x = +5? ?(d)Pure silverIron spoonAg+(aq) 3.(a)(i) Soap.?1(ii) Concentrated NaCl/ Brine/ NaCl(l)?1 (iii) To precipitate out the soap?1 (iv) potassium hydroxide/ KOH(aq)?1 (v)- Cleansing agent is made up of non- polar (hydrocarbon) and polar (head)? ?- When mixed with oil /grease, the hydrocarbon part is attracted to it.? ? while the polar part stays in water ? ?- The oil particles are broken and carried off to the solution.?1(b)(i) Uv light(ii) A ethaneB1-chloroethane(iii) It is non biodegradable hence causes environmental pollution.any one(iv) Ihydrogenation IVhalogenation(v)-add concentrated sulphuric (vi) acid to ethane to form ethylhydrogensuplphateC2H4(g) + H2SO4(l)→C2H5OSO3H(aq)√1Page | 8900Chemistry paper 1, 2&3 -add water to the mixture.ethylhydrogensulphate is hydrolysed to ethanol CH3CH2OSO3H(aq) +H2O(l)→ CH3CH2OH(aq) + H2SO4(aq)√14.(a) The overall heat change of a reaction is the same regardless of the route through which the reaction occurs.(b)(i)Ca (s) + C (s) +O2 (g)?H1=? CaCO3 (s)?H2=?H2=-394kJ/mol ?H4=+178 kJ/mol-635 kJ/mol+? O2 (g)+ O2 (g)CaO (s) + CO2 (g)(ii)?H1= ?H2 +?H3 + ?H4(1mk)= -635 + (-394) - (+178)= -1207 kJ/mol5.(a) Solubility is the maximum mass of solute that dissolves in 100 g of a solvent at a particular temperature.(b)(a)(b)(i) X:31.5 (±0.2) g/100g of waterY: 36.6 (± 0.2 g/100g of water(ii)60.5 ±1 oC(c)60-20.7 =39.3 g(d)13 g (1 mk) of X will crystallize, salt Y will be in solution (1 mk) . The solubility of X is lower than the mass dissolvedwhile that of N is higher than the mass dissolved.(1 mk)(e) Fractional crystallization (any one)6.(a) ARoasting ?EElectrolysis ?(b) BCarbon ? 1mkCdil. Sulphuric acid?Ddil. Sulphuric acid ?(c) ZnO(s)+ C (s )→ Zn(s) + CO (g)(d)Pure zinc anodeImpure zinc cathodeZinc sulphate(e)-Electroplating of iron sheets-Zinc case for dry cells-Making alloys e.g. brass7. (a)(i)2Pb(NO3)2(s)2PbO(s) + 4NO2 (g)+ O2(g)(ii)-brown fumes of NO2-solid residue is red when hot but on cooling it becomes yellow(iii)Lead (II) nitrate crystalises without water of crystalisation that would interfere with the NO2 formed(iv) By using a glowing splint. Gas A relights a glowing splint(b) (i) dinitrogentetraoxide(ii)2NO2(q) cool N2 O4(l)(c)(i)(Pb = 207, Cl = 35.5, Na = 23)Pb(NO3)2 (aq) + 2NaCl(aq)→ PbCl2(s) + 2NaNO3(aq)1mol→1mol117g→278 g2.34g →xx = 2.34 x 378117= 5.56g of PbCl2(ii)2OH-(aq)+ Cl2(g)→Cl-(aq) +OCl-(aq) + H2 O(l)Penalise fully if wrong state symbols or state symbols are missing.Page | 9000Chemistry paper 1, 2&3 KAMDARA JET - 2016 233/1 CHEMISTRY (THEORY) PAPER 1 JULY/AUGUST 2016 2 Hours 1. A Student in form four placed a thermometer in molten naphthalene at 850C and recorded the temperature and time until the naphthalene solidified. From the values obtained, the figure below was drawn. (a) What name is given to such a figure?(1mk)(b) Which part of the figure represents the change of state of naphthalene?(1mk)(c) In terms of kinetic theory. Explain what happens to molecules along AB.(1mk)2.In a certain reaction, 18.7cm3 of a dibasic acidH 2Xrequired 25cm3 of 0.1M NaOH for complete neutralization.(a) How many moles of Sodium hydroxide are contained in 25cm3?(1mk)(b) Calculate the molarity of the dibasic acid.(2mks)3.Study the flow chart below and answer the questions that follow.(a) Identify solid G(1mk)(b) Write a balanced chemical equation between the yellow solid and dilute nitric acid.(1mk)(c) Write the formula of the complex ion in solution F(1mk)4.Explain this observation:When hydrogen chloride gas is dissolved in water, the solution conducts electricity while a solution of hydrogen chloride gasin methyl benzene does not conduct electricity.(2mks)5.Matter exists in three states which can be related as shown in the diagram below.(a) Name processes: P:(1mark)R:(1mark)(b) Explain whether process Q is exothermic or endothermic(1mark)6.(a) What is meant by allotropy?(1mark)(b) Name two allotropes of carbon.(1mark)(c) Give one use of charcoal in the sugar refinery industry.(1mark)7.(a) State Graham?s Law of Diffusion(1mark)(b) A given volume of ozone (O3) diffused from a certain apparatus in 96 seconds. Calculate the time taken by an equalvolume of carbon(IV) oxide to diffuse under the same conditions. (C=12,O=16)(2marks)8.(a) Name two ores from which copper is extracted.(1mark)(b) During the extraction of copper metal the ore is subjected to froth floatation. Give a reason why this process is necessary.(1mark)Page | 9100Chemistry paper 1, 2&3 (c) One of the alloys of copper is brass. State its two uses.(1mk)9.Draw a dot (? ) and cross (X) diagram to show bonding in sulphur (IV) oxide(1mk)10. A form one class carried out an experiment to determine the active part of air. The diagram below shows the set-up of theexperiment and also the observation made.(a) Identify substance M(1mk)(b) State two reasons for the suitability of substance M for this experiment(1mk)(c) Write the equation for the reaction of substance M and the active part of air(1mk)11.(a) Complete the following equation(1mk)(b) Name the homologous series to which the following compounds belong?(i) CH3CCH(1mk)(ii) CH3CH2OOCCH3(1mk)12. The table below shows the pH values of solutions J to NSolutionJKLMNpH5132107(a) Which solution contains the largest concentration of hydroxides ions?.....(1mk)(b) Which solution is likely to be a solution of acetic acid?....(1mk)13. The scheme below was used to prepare a cleansing agent. Study it and answer the questions that follow. FatSolution of cleansing agent +alcohol Step IISolid cleansing agenti)What name is given to the type of cleansing agent prepared by the method shown in the scheme?(1mk)ii) Name one chemical substance added in step II(1mk)iii) What is the purpose of adding the chemical substance named in (ii) above.(1mk)14. a) Define half - life of radio isotopes.(1mk)b) Z grammes of a radioactive isotope take 100 days to decay to 20gms. If the half - life of the element is 25 days. Calculate the initial mass of Z of the radio- isotope. (2mks 15. Magnesium was burnt in air forming a white residue T. When put in a boiling tube with water effervescence was noticed and colourless gas D with a characteristic pungent smell was evolved. The gas turned a wet red litmus paper blue. (a)Identify(i)Residue T(1mk)(ii)Gas D(1mk)(b)Write an equation for liberation of gas D.(1mk)16. Explain why the bleaching action of chlorine is permanent while bleaching by sulphur (IV) oxide is temporary. (2marks)17. Explain how you would separate a mixture of nitrogen and oxygen gases given that their boiling points are -196oC and -183oCrespectively.(3mks)Page | 9200Chemistry paper 1, 2&3 18 Hydrazine gas, shown below, burns in oxygen to form nitrogen gas and steam. (a) Write an equation for the reaction(1mk)(b) Using the bond energies given below, calculate the enthalpy change for the reaction in (a) above(2mks)BondBond energy KJ per moleN N944N N163N H388O O496H O46319 Using reagents provided only, explain how you could prepare solid Zinc carbonate.(2mks)? Zinc powder ? Nitric (V) acid (dilute) ? Water ? Solid sodium carbonate 20 The apparatus below was set up to show the catalytic oxidation of ammonia. (a) Identify the brown fumes observed at the mouth of the conical flask.(1mk)(b) Write down the equations of the reactions representing(i) Catalytic oxidation of ammonia(1mk)(ii) The formation of the brown fumes.(1mk)21 Consider the chromatogram below.ABCDEFBlackYellowRedBlueGreenA piece of chromatogram paper was spotted with colour inks obtained from pens labeled A to F. The diagram above showsthe spots after the chromatograph was developed.(a) Which two pens contained the same pigment?(1mk)(b) According to the chromatogram which pigments are present in the inks of the pen number F(1mk)(c) Describe how one could get a sample of yellow pigment(1mk)22. Consider the following reaction at equilibrium.PCl 5?g??PCl3?g??Cl2?g?Complete the table below to show the effect of different factors on the position of equilibrium.(3mks)FactorEffect on the equilibrium position(i) Decrease pressure(ii) Removing chlorine(iii) Adding Helium gas to mixturePage | 9300Chemistry paper 1, 2&3 23. A student investigated the effect of an electric current by passing it through some substances. The student used inert electrodes and connected a bulb to the circuit. The table below shows the substances used and their states. ExperimentSubstanceState1Potassium carbonateSolid2Copper (II) sulphateSolution3SugarSolution4Lead (II) iodideMolten(a) In which experiments did the bulb not light?(1mk)(b) Explain your answer in (a) above.(2mks)24.Give a reason why the formula mass of NO2 is sometimes 92 instead of 46.(1mk)25.A compound contains only carbon, hydrogen and oxygen .Combustion of 1.068g of the compound produces 1.601g of carbon(IV) oxide and 0.437g of water. The molar mass of the compound is 176.1?. What is the empirical and molecularformulae of the compound?(2mks)26.(a) A sample of water in a beaker was found to boil at 102 at 1 atmospheric pressure. Assume that the thermometer wasnot faulty explain this observation(1mk)(b) Study the information in the table below and answer the questions that follow.SaltSolubility (g/100g water)At 40At 60CuSO42838Pb(No3)27998A mixture containing 35g of CuSO4 and 78g of Pb(NO3)2 in 100g of water at 60 was cooled to 40(i) Which salt crystallized out? Give a reason.(1mk)(ii) Calculate the mass of the salt that crystallized out.(1mk)27.A student was asked to determine the percentage of zinc metal in a mixture of zinc metal and zinc oxide. He reacted themixture with excess hydrochloric acid and accurately collected the gas evolved, which was then used to calculate the amountof zinc in the mixture.(a) Name the gas that was evolved.(1 mark)(b) Apart from the reaction liberating the gas write a balanced equation for the other reaction that took place.(1 mark)(c) Why would dilute nitric acid not suitable for this reaction?(1 mark)28.Below is part of the flow diagram of the contact process.Liquid MCHAMBERSO3CHAMBER Concentrated Sulphuric (VI)Liquid N(a) Identify (i) Liquid M(ii) Liquid N(b) Write the equation for the reaction taking place in chamber B. 29. Chlorine gas dissolved in distilled water to form chlorine water(a) Name the compounds present in the chlorine water.(b) What would be observed if blue litmus paper is dipped in chlorine water? Explain.acid(1mk)(1mk)(1mk)(1mk)( 2mks) 30. A fixed mass of gas occupies 105cm3 at -14 and 650mmHg pressure. At what temperature will it have a volume of 15cm3if the pressure is adjusted to 690 mmHg pressure(2mks)Page | 94Chemistry paper 1, 2&3 KAMDARA JET - 2016 233/2 CHEMISTRY Paper 2 THEORY JULY/AUGUST 2016 2 Hours 1.The grid below represents part of the periodic table. Study it and answer the questions that follow. The letters do not representthe actual symbols of the element.NSKQOPFMR a)What name is given to the group of elements to which Q and R belong?(1 mark)b)Write the formula of the compound formed when Q and P combine.(1 mark)c)Name the type of bond formed in (b) above.(1 mark)d)How does the atomic radii of O and P compare? Give a reason.(2 marks)e)Draw a dot (.) and cross (x) diagram for the compound formed between N and F.(1 mark)f)Explain how you would obtain a pure sample of the carbonate of K from its mixture with Lead carbonate powder. (2 marks)g)Give one use of element M.(1 mark)h)The melting point of M is -189oC lower than that of F -102oC. Explain this difference in their melting points.(2 marks)2.The list below shows the formulae of some organic compounds. Use letters T1 to T6 to answer the questions that follow.T1 - CH3CH2CH2CH2CH3T2 - CH3CH2CH2COOC2H5 T3 - CH3CH2CH2CH2OH T4 - CH3CH2CH2COOH T5 - CH3CH2CHCH2 T6 - CH3CCCH3 (a)Select two compounds which:(i)Are not hydrocarbons(1mk)(ii) Would decolourise both bromine water and acidified potassium manganite (VII)(1mk)(iii) Would produce hydrogen gas when reacted with potassium metal(1mk)(b) Select a compound which would produce bubbles of a gas when reacted with sodium carbonate.(1mk)(c)(i) Identify the compound that is likely to undergo polymerization. Give a reason for your answer. Using two moleculesshow how polymerization occurs.pound(1mk)II. Reasons(1mk)III. Polymerization(1mk)IV Name the process by which compound T2 is formed and identify the compounds that were used to form it.I. Process(1mk)pounds(1mk)(d) Compound T3 can be converted to T4 as shown by the equation below:C4H9OH(l) + O2(g)→C3H7COOH(aq) + H2O(l)Given the following information:ΔHc for C4H9OH = - 4910 kJ/molΔHc for C3H7COOH = - 4090 kJ/molDetermine the heat change for the reaction above.(2mks)3.a) What is meant by the term molar enthalpy of combustion?(1mks)b) The enthalpies of combustion of carbon, hydrogen and ethanol are given below.C(s)+ O2(g)→CO2(g) ? H = -393kJmol-1H2(g) + ? O2(g)→H2O(l) ?H = - 286 kJmol-1Enthalpy of combustion of ethanol ?H = -1369kJ/ moli)Draw an energy cycle diagram that links the enthalpy of formation of ethanol to enthalpies of combustion of Carbon,hydrogen and ethanol. (3 marks)ii) Determine the enthalpy of formation of ethanol(1 marks)c) An experiment was carried out where different volumes of dilute nitric acid (v) acid and aqueous potassium hydroxideboth at 25oC were mixed and stirred with a thermometer.Page | 9500Chemistry paper 1, 2&3 The highest temperature reached by each mixture was recorded in the table below. Volume of nitric (V) acid (cm3)4812162024283236Volume of potassium hydroxide cm33632282420161284Highest temperature of mixture19.822.224.627.027.025.023.021.019.0Plot a graph of highest temperature (vertical axis) against volume of nitric acid. (horizontal axis) 3mksUsing your graph, determine the;i)highest temperature reached(? marks)ii) The volume of the acid that reacted when the highest temperature is reached.(? marks)iii) The amount of heat liberated during the neutralization process(Specific heat capacity is 4.2jg-1K-1 and the density of solution is 1.0gcm-3(2 marks)d) The molar enthalpies of neutralization for dilute hydrochloric acid and dilute nitric (v) acid are -55 KJmol-1.while that ofethanoic acid is -52.2kJ/mol. Explain this observation.(2 marks)4.Experiment was set as shown below.(a) What is observed on the bulb when the switch is closed?(1mk)(b) Which electrode will be cathode?(1mk)(c) Write down the half-cell equations for:(i) Copper electrode.(1mk)(ii) Zinc electrode.(1mk)(d) Write the overall ionic equation for the electrochemical cell.(1mk)(e) The table below shows the electrode potentials.Cu2+ (aq) + 2e-→Cu(s) E= + 0.34VZn2+ (aq) + 2e-→Zn(s) E= - 0.76VWhat is the value of the voltage of the cell?(2mks)(f) The switch is kept closed. State and explain the observation expected after sometime on the(i) The zinc rod.(2mks)(ii) Copper (II) Sulphate solution.(2mks)5.The chart below represents the extraction of iron and some of its uses.Raw materialsexhaust gasesWroughtBlastPig IronHot airfurnaceMolten ironHCL (aq)slagStep ISolution AStep IV (NH3 (aq)Solid xSteelIronIron fillingsSteam Step IIStep IIICl(g)Black Solid C + gas YSolidB Page | 9600Chemistry paper 1, 2&3 (a) Name the raw materials fed into the blast furnace.(2mks)(b) Name 3 exhaust gases emitted from the blast furnace.(1?mks)(c) (i) Why is it necessary to convert pig iron into wrought iron(1mk)(ii) State one commercial use of iron.(1mk)(d) Name substances A,B,C,X,Y (2?mks)(e) i) Write equations for reactions in steps II and IIii) Write an ionic equation for the reaction in step I.(1mk)iii) What observations are made in steps Iand II?(2mks)6.Study the flow chart below and answer the questions that follow.BrineAmmoniacalTower PBrineGas QHeatingGas MLimestoneAdd waterChamber KLa) Name Gas M (1 mark)b) Name solution F and solid XSolution F -Solid X -c) Name the product L formed and give one of its uses Product L -Use -d) Write equation of the reaction in the;i) tower P -ii) chamber K -e) Name two raw materials required in the manufacture of Sodium carbonate f) Write an equation of the reaction when solid x is heated.FilterSolutionFChamber CSolid XHeatNa2CO3(1 mark)(2 marks)(2 mark)(2 marks)(1 mark) 7.The table below shows the volume of nitrogen (IV) Oxide produced when different volumes of 1M Nitric (V) acid - wereeach reacted with 4.14g of lead at room temperature.Volume of 1 M Nitric (V) acid (cm3)Volume of Nitrogen (IV) oxide gas (cm3)1012030360506007084090960110960(a) Explain how the rate of the reaction between lead and nitric (V) acid would be affected if the temperature of the reactionmixture was lowered.(1mks)(b) On the grid provided below plot a graph of the volume of the gas produced (vertical axis) against volume of acid. (3mks)Page | 97Chemistry paper 1, 2&3 (c) Using the graph, determine the volume of (i) Nitrogen (IV) oxide produced when 60cm3 of 1M Nitric (V) acid were reacted with 4.14g of lead.(1mk)(ii)1M Nitric (V) acid which would react completely with 4.14g of lead.(1mk)(d) Using the answer in d(ii)above, determine(i) The volume of 1M Nitric (V) acid that would react completely with one mole of lead. (Pb = 207).(2mks)(e) Calculate the number of moles of(i)1M Nitric (IV) acid reacted with one mole of lead.(1mk)(ii) Nitrogen (IV) oxide produced when one mole of lead were reacted with excess nitric acid.(Molar gas volume is 24000cm3).(1mk)(f) Using the answers obtained in e(i) and e(ii) above; write the equation for the reaction between lead and nitric (V) acid giventhat one mole of lead (II) nitrate and two moles of water were produced.(1mk)(g) Give a reason why nitric (V) acid is stored in dark bottles.(1mk)Page | 9800Chemistry paper 1, 2&3 KAMDARA JET - 2016 233/3 CHEMISTRY Paper 3 (PRACTICAL) July 2016 2? hours 1.You are provided with:?Solid P?2.0M hydrochloric acid, solution Q?0.1M sodium hydroxide, solution RYou are required to determine the enthalpy change ? H, for the reaction between solid P and one mole of hydrochloric acid. Procedure I Transfer 20.0cm3 of 2.0M hydrochloric acid, solution Q in a 100ml.beaker using a burette. Measure the temperature of the solution after every half-minute and record the values in Table 1. At exactly 2? minutes, add all of solid P to the acid carefully. Stir the mixture gently with the thermometer. Measure the temperature of the mixture after every half-minute and record the values in Table 1. (Retain the mixture for use in procedure II) Table 1 Time(min)0?11?22?33?44?5Temperature (oC)X(5 mks)(i) Plot a graph of temperature (y-axis) against time.(3 mks)(ii) Using the graph, determine the change in temperature ? T.(1 mk)(iii) Calculate the heat change for the reaction (Assume that the specific heat capacity of the mixture is 4.2 Jg-1K-1 and the density of the mixture is 1g/cm3).(2 mks)Procedure II Rinse the burette thoroughly and fill it with sodium hydroxide. Transfer all the contents of the 100ml. beaker in procedure I into a 250ml. volumetric flask. Add distilled water to make up to the mark. Label this as solution N. Using a pipette filler, place 25.0cm3 of solution N into a 250ml. conical flask. Add two or three drops of phenolphthalein indicator and titrate against solution R. Record your results in table 2. Repeat titration two more times and complete Table 2. Table 2 IIIIIIFinal burette reading(cm3) Initial burette reading(cm3) Volume of solution R used (cm3) (3 mks) Calculate the: (i) average volume of sodium hydroxide solution R.(1 mk)(ii) the number of moles of :ISodium hydroxide solution R.(1 mk)IIhydrochloric acid in 25cm3 of solution N.(1 mk)IIIhydrochloric acid in 250cm3 the of solution N(1 mk)IV hydrochloric acid in 20.0cm3 of solution Q(1 mk)V hydrochloric acid that reacted with solid P(1 mk)(c) Calculate the enthalpy of reaction between solid P and one mole of hydrochloric acid. (Show the sign of ? H). (2 mks) 2 You are provided with solid E. Carry out the following tests and write your observations and inferences in the spaces provided. a) Place all of solid E into a boiling tube. Add about 12cm3 of distilled water and shake thoroughly. Filter the mixture and place the filtrate into another boiling tube. Dry the residue using pieces of filter paper. Retain the filtrate for use in 2(b) below. Page | 99Chemistry paper 1, 2&3 (i) Transfer half of the dry residue into a dry test tube. Heat the residue strongly and test any gas produced using a burning wooden splint. ObservationsInferences(2 mks)(1 mk)(ii) Place the other half of the residue in a dry test-tube. Add 4cm3 of 2M nitric acid. Retain the mixture for test (iii) and (iv)below .ObservationsInferences(1 mk)(1 mk)(iii) To 2cm3 of solution obtained from a(ii) above, add aqueous ammonia drop by drop until in excess.ObservationsInferences(? mk)(? mk)(iv) To 2cm3 of the other solution obtained in a(ii) above, add 2cm3 of potassium iodide solutionObservationsInferences(1 mk)(1 mk)(b) Divide the filtrate obtained in 2(a) above into 5 portions.(i) To the first portion of the filtrate add aqueous ammonia drop by drop until in excess.ObservationsInferences(1 mk)(1 mk)(ii) To the second portion of the filtrate add 2 drops of sodium sulphate solution.ObservationsInferences(? mk)(? mk)(iii) To the third portion of the filtrate, add 2 drops of barium nitrate solution followed by about 2 cm3 of nitric acid solutionObservationsInferences(1 mk)(1 mk)3.You are provided with solid F. Carry out the tests below and record your observations and inferences in the spaces provided.(a)(i) Using a metallic spatula, heat half of solid F in a non-luminous Bunsen burner flame for some time then remove when itignites.ObservationsInferences(1mk)(1mk)(b) Put a half spatula endful of solid F into a boiling tube. Add about 10cm3 of distilled water and shake vigorously.Divide the resulting solution into two portions.(i) To the first portion, dip a piece of universal indicator paper and determine its pHObservationsInferences(? mk)(? mk)(ii) To the second portion, add two drops of acidified potassium manganate (VII) solution and shake vigorously.ObservationsInferences(1 mk)(1 mk)Page | 10000Chemistry paper 1, 2&3 KAMDARA JET -2016 MARKING SCHEME 233/1 CHEMISTRY 1.ANSWERS;(a) Cooling curve?1 (b) BC?1 (c) The kinetic energy ?? of the molecules decrease as heat energy is lost?? to the surrounding leading to a drop / decrease in temperature. 2.Ansa)1000cm3 = 0.1mol25 ?01? 25 cm3???= 0.0025mol. ??1000b) H2X (aq) + 2 NaOH (aq)→ Na2X(aq) + H2 O(l)Mole ratio 1 : 2??Moles of acid= 0.0025??2 = 0.00125mol. Molarity= 1000 x 0.00125??18.7= 0.0668M??3.(a) Lead (II) nitrate /Pb(NO3)2? 1mk(b) PbO(s)+ 2HNO3(aq)→ Pb(NO3)2 (aq) + H2O(l) ?1(c) [Pb(OH)4] 2- (aq)?14.HCl solution in water forms ions/ionizes which conduct electricity. ? 1HCl solution in methyl benzene does not form ions/ionize// is molecular ?? 15.ANSWER(a) P= Sublimation // sublimate formation(1 mark)R= Solidification //freezing(1mark)(b) Exothermic(1 mark)Slowing down particles release their kinetic energy as the gas condenses to liquid(? mark)6.(a) Existence of an element in more than one physical form in the same state?1(b) Graphite ? ? and diamond? ?(c) Adsorbing coloured impurities ?17.(a) Under the same conditions of temperature and pressure, the rate of diffusion of a gas is inversely proportional to thesquare root of its density. ?1(b) TO3=RMM O3TCO2RMMCO2962 =48 2TCO2449216= 48TCO2 244(TCO2)2 = 44 x 921648TCO2=8448= 91.913seconds(1mk)8.ANSWERa)Copper pyrate (1/2mk) // malachite (1/2) Cuprite //Bornite //Chalcucite. (Any two mentioned 1/2mk each)b)To concentrate the ore or Remove impurities(1mk)c)Making-Door handles-coinageany two(1mk)-Batteries9.ANSWERPage | 10100Chemistry paper 1, 2&310. ANSWER(a) Phosphorus(1mk)(b) Phosphorus smoulders/ Reacts with oxygen(1/2mk)Phosphorus does not react with water(1/2mk)(c)( )()( )()(any I mk)( )()( )()11. ANSWER(a) Answer(I mk)(b)(i) Alkynes√1 (ii) Esters√112.(a) K(b) J13.(i) Soap or soapy detergent ?1mkii) Sodium chloride ?1mkiii)- To solidify the soap-Separate out the soap-Reduces solubility of soap-Precipitate soap-Salting out the soapany 1?1mk14. a) It is the time taken by radio isotope to decay by half its initial value.?1b) No. of t ? = 100 = 4 ??? 25320 gms1st160gms2nd80gms 3rd40gms4th20gms?1Initial mass = 320g ???15.(a)(i)Magnesium nitride / Mg3N2(1mk)(ii)Ammonia / NH3(g)(1mk)(b) Mg3N2(s) + 6H2O(l)→3Mg(OH)2(s) + 2NH3(g)(1mk)16. The dye is oxidized to a new product with chlorine (1mk) but oxygen is removed to form an unstable product which graduallygets re-oxidized by atmospheric oxygen on exposure for some time to air (1mk) in the case of Sulphur (IV) oxide.17. Compress and cool to liquefy√1Fractionally distil the liquid air.√1The gases separate nitrogen gas first.√118. Ansa) N2H4 +O 2(g) →N 2(g) +2H20(g)(1mk)(penalize for state)b)H= Bond breaking + Bond formation energies.= (163+4(388) + 496)+ (944+4(463))(1mk)= (+2211kJ + -2796kJ)(? mk)=-585kJ(? mk)(Must be pleasant to score)19. Answer;Add excess Zinc powder to Nitric (V) acid Zn(s)+2HNO3(aq)→Zn(NO3)2(aq) + H2O(l)(?mk)Dissolve solid sodium carbonate in water Na2CO3(s) + water→Na2CO3(aq)(?mk)Mix the resulting mixture with zinc nitrate solutionNa2CO3(aq) + Zn(NO3)2(aq)→ZnCO3(s) + 2NaNO3(aq)(?mk)Filter out zinc carbonate and dry it.(?mk)20.(a) Nitrogen(IV) oxide(NO2) gas(1mk)(b) (i) 4NH3(g) +5O2(g) →4NO(g) + 6H2O(g)(1mk)(ii) 2NO(g) + O2(g) → 2NO2(g)(1mk)21.(a) D and E(1mk)(b) Green, blue, yellow and red(1mk)(c)- Cut out the yellow pigment(?mk)-put in organic solvent to dissolve the pigment(?mk)-filter and evaporate the filtrate to get the pigment22.-Equilibrium shift to the right(1mark)-Shift to the right(1mark)-Shifts to the left ( equivalent to increase in pressure)(1mark)Page | 10200Chemistry paper 1, 2&3 23. a) Experiment 1 (1/2mk) and 3 ( 1/2mk) (Ans. not tied) b) In experiment 1 the ions in K2CO3 are tightly held in position and cannot move.(1mk)While in sugar solution, there are no ions for it exists in molecular form(1mk)// No mobile ions which can carry the current.24. NO2 dimerises to form N2O4 (1mk)25. Mass of((?mk)CHOMoles(?mk)=0.0486Mole ratio(?mk)Empirical formulaCHO(?mk)Molecular(?mk)formular26. Ansa) The water contained impurities (1mk) //presence of impurities elevate the Bpt.Or water contained dissolved ions//Hard.b)(i) Copper(II) sulphate; (1/2mk) at 400C ONLY 28gm (1/2mk) is soluble leaving the rest undissolved.At 400C, all lead nitrate dissolves.(1mk)(ii)35-28=7g(1mk)27. Ans(a) Hydrogen gas(1 mk)(b) ZnO(s)+ H2SO4(aq) → ZnSO4(aq)+ H2O(1 mk)(c) Nitic acid being a strong oxidising agent oxidizes hydrogen formed to water no gas is therefore evolved.(1 mk)28. AnsLiquid M - conc. sulphuric (VI) acid (1 mk) / H2SO4(l)Liquid N - water /H2O(1 mk)(b) H2S2O7(l) + H2O(l) ? 2H2SO4(l)(1 mk)29. Ansa ) Hydrochloric acid ?? and Chloric I acid??b) Turn colourless (1 mk); chlorine water has HOCl which is a bleaching agent(1 mk)30. V1P1= P2 V2 ? ?T1T2105 x 650= 15 x 690 ? ?259T2T2 = 15 x 690 x 259? ? 105 x 650 = 2680650? ? 68250 = 39.276923 K ?or= 39.28 KPage | 10300Chemistry paper 1, 2&3 KAMDARA JET - 2016 233/2 CHEMISTRY MARKING SCHEME 1.a) Alkaline earth metals(1mk)b) Q2P2 →QP - NB: metal should be followed by a non-metal and not vice versa.(1mk)c) Ionic bond.(1mk)d) The atomic radius of P is smaller than that of O. P has higher/stronger nuclear force of attraction than O P has more number of protons than O. NB: Comparative words MUST be used.(2mk)e) NB: outermost electrons in the atoms of F must be shown(1mk)f) Add water to the mixture of K carbonate and lead carbonate and stir. K carbonate dissolves while lead carbonate does not. Filter to obtain K carbonate solution as a filtrate and lead carbonate as the residue. Evaporate the filtrate to obtain crystals of carbonate of K Wash the residue with distilled water and dry between filter papers. (2mks) g) Used in light bulbs to provide an inert environment to prevent oxidation. NB: reject used to make light bulbs. Used as an insulator in arch - welding.(1mk)h) M is a monoatomic gas while F is a diatomic gas; the Van der waal forces in M are weaker than in F hence the low m.p.t(2mks)2.(a) (i) T2 and T3 / T2 and T4/T3 and T4/I(1mk)(ii) T5(1mk)(iii) T3(1mk)(b) T4(1mk)(c)(i) T5 or T6(1mk)(ii) Reason: it is unsaturated(1mk)(iii) Polymerization(1mk)(1mk)(iv)(I) Process: Esterification(1mk)(II) Compounds(1mk)(i) Butanoic acid(CH3CH2CH2COOH)(ii) Ethanol(C2H5OH)Page | 104Chemistry paper 1, 2&3 (d) C4H9OH + O2(g)?H2C3H7COOH + H2O(l)?H3?H14 CO2 + 5H2O (l)(1mk)?H2 = ?H1-?H3(1mk)= 4910-4090= -4910 + 4090= -820 kJ/mol3.a) The amount of heat liberated when one mole of a substance is burnt completely in excess oxygen.rej- heated in oxygenrej- heated required to burn ….NB: burning must be completeb) i)2C (s)+3H2(g)+ ? O2(g)?HfC2H5OH(l)?HC H2 +3/2 O2?HC C2H5OH?HC+ O2+ 5/2O2 CO2(g) + 3H2O(l) Correct energy cycle - 1mark Arrows pointing right - 1 mark Balancing all the equations - 1mark NB: If an energy level diagram (axis labelled) is drawn with correct arrows award.(2marks)ii)?H1=?H2 +?H32(-393) + 3(-286) = ?H2 + - 1369?Hf =?H2= -786 + - 858 + 1369 kJmol-1(J) must be capital= -275 kJ/Mol(2mks)Penalize ( ? marks) if units missing.Penalize ( ? mark if -ve sign is missing.c)I)NB: Straight lines ? mk each Extrapolation ? mk Axis label ? mk each Volume of HNO3 (cm3) i) xoC - must be read from the extrapolated value from the graph. (? mk) ii) Vcm3 - must be read from the graph correctly. ( ? mk) iii) ?H= MC?T= (acid + base) x 4.2x ?T - Extrapolated value from the graph - initial temparature From the graph40- volume of acid( 1mk)NB: final answer must have -ve sign otherwise penalise (? mk)d) Ethanoic acid is a weak acid therefore heat is used to ionize it before neutralization occurs.4.a. The bulb lights(1mk)b. Copper rod(1mk)c.i.Cu2+(aq) + 2e ----------------? Cu(s)(1mk)Page | 105Chemistry paper 1, 2&3 ii.Zn(s) --------------------? Zn2+(aq) + 2e(1mk)d. Zn(s) + Cu2+(aq) --------? Zn2+(aq) + Cu(s)(1mk)e.+0.34--- 0.76v = 1.10v(2mks)f.(i) The zinc rod becomes thinner because it dissolves in solution forming ions(2mks)(ii) The blue colour of copper(ii) sulphate solution fades, because the copper ions are being removed from the solutionforming copper solid(brown)(2mks)5.(a) limestoneCoke, haematite/ Magnetite/ Sidesite etc(1mk)(b) CO2, CO, N2(1 mks)(c)(i) pig iron is brittle(1mk)(ii) Building - bridges , roofs, car bodies(1mk)(d) A - iron (ii) Chroride(2 mks)B - Iron (iii) Chloride C - Tri-iron tetra-oxide X - Iron (ii) hydroxide Y - Hydrogen (e) (i) II3Fe(s) + 4H2O(g) →Fe3O4(s) + 4H2(g)III2Fe(s) + 3Cl2→2FeCl3(s)Balanced equation? mk Zero for not balancingMissing state Symbols penalize ? mk(ii) Fe2+(aq) + 2OH-(aq)→ Fe(OH)2(s)(iii) IGreen ppt 1mkIV Brown ppt1mk6.a) Ammonia NB: if formula written then it must be correct otherwise penalize fully.(1mk)b) Ammonium chloride - F( mk)x - Sodium hydrogen carbonate ()c) L - Calcium chloride (1mk)Used as a drying agent. 1mk)d) i) NaCl(aq) + NH3(g)+ CO2(g) + H2O(l)→ NH4Cl(aq) + NaHCO3(s) (1mk)ii) CaO(s)+ H2O(l)→ Ca(OH)2(aq) (1mk)e) Carbon (IV) oxide ( maximum 2mks)-Ammonia gas-Sodium chloridef)2NaHCO3(s)→ Na2CO3(s) + CO2(g) + H2O(l) (1mk)NB: if the equation is not balanced award 0 marks7.(a) Decrease kinetic energy of the molecules would decrease(1mk)The number of effective collision would decrease(b) GraphPlotting1mkCurve1mkScale on both axes1mk(c)(i)720cm3 ± ? square of the graph(1mk)(ii)80cm3 ± ? square of the graph(1mk)(d)(i) Moles of Pb == 0.02(1mk)Volume of nitric acid the react with one mole (ii)960/0.02 = 48000(1mk)( ) (e)(i) Value in= 4(1mk)()(ii)= 2(1mk)(f) Pb(s)+ 4HN03(aq)→ Pb(NO3)2(aq) + 2NO2(g) + 2H2O(l)(1mk)(g)4HNO3 (aq)→- 4NO2(g) + O2(g) + 2H2O(l)(1mk)Nitric(V) acid decomposes into Nitrogen (iv)Page | 10600Chemistry paper 1, 2&3 KAMDARA JET - 2016 233/3 MARKING SCHEME ii)? T = 21.0-14.6 = 6.4K (the value 14.6 is obtained from the graph)iii)? H = 20g x 4.2Jg-1K-1 x (ans in (ii) above) = correct ans.Table 2IFinal burette reading(cm3)12.4Initial burette reading(cm3)0.0Volume of solution R used (cm3)12.4(i)=12.37 cm3S.V. 12.37cm3( )(ii) IIImoles HCl = ans (II)(mole ratio 1: 1)()IIIIV( correct answer only)V ans(IV) - ans (III) = correct ans.()(c)IIIII24.812.3112.40.012.412.3(3 mks) ()(penalize if units kJmol-1 or Jmol-1 not included) 2 b) (i) ObservationsInferences- colourless gas puts off burning splint- red brown solid form and on coolingPb2+ ions presentchanges to yellow solid.- blue litmus changes to faint red- red litmus paper unchanged( 2 mks)( 1 mk)Page | 107Chemistry paper 1, 2&3 (ii) ObservationsInferences-effervescenceCO32- or HCO3- ions present-colourless solution formed( 1 mk)( 1 mk)(iii)ObservationsInferencesWhite precipitate insoluble inAl3+ or Pb2+ ions presentExcess(? mk)(? mk)(iv)ObservationsInferences-Bright yellow precipitate formsPb2+ ions present(1 mk)(1 mk)(b) (i) ObservationsInferences-White precipitate soluble in excessZn2+ ions present(1 mk)(1 mk)(ii) ObservationsInferences-No white precipitateCa2+, Ba2+ or Pb2+ ions absentOr Zn2+ ions present(? mk)(? mk)(iii) ObservationsInferences-White precipitate insoluble in diluteSO42- ions presentnitric acid(1 mk)(1 mk)3.(a)(i) ObservationsInferences-burns with yellow sooty flame- C=C- or -C= C- presentOr long chain hydrocarbon/ unsaturated compoundReject: alkanes,alkenes,alkynes, carbon carbondouble bond or triple bond present.(1mk)(1mk)(b)ObservationsInferencespH = 5weakly acidic compound(? mk)(? mk)(ii)ObservationsInferences- Instant decolourisation- C=C- or -C=C- or -OH presentOr change from purple to colourless(1 mk)(1 mk)Page | 10800H oH oH oChemistry paper 1, 2&3 NANDI EAST, NANDI SOUTH & TINDERET SUB-COUNTIES JOINT EVALUATION 2016 233/1 CHEMISTRY PAPER 1 THEORY JULY / AUGUST 2016 TIME: 2 HOURS 1. The diagram below represents a flame of the Bunsen burner. Piece of white paper (i) A piece of paper is flipped over the flame as shown in the diagram. Draw a sketch to show the outcome.(1mk)(ii) State two reasons why laboratory apparatus are made of glass.(1mk)2.(a) Distinguish between atomic number and mass number.(1mk)(b) An isotope M has 20 neutrons and a mass number of 37.(i) Draw the atomic structure of M.(1mk)(ii) To which group does M belong? Explain.(1mk)3.Using relevant equations show that zinc oxide is an amphoteric oxide.(3mks)4.(a) State the Gay Lussac?s Law.(1mk)(b) When 75cm3 of a gaseous hydro-carbon CxHy burns in 250cm3 of oxygen, 25cm3 of oxygen is unused, 150cm3 of carbon(IV) oxide is formed. Determine the volume of steam formed hence deduce the formular of the Hydro-carbon.(2mks)5.(a) Give the name of the following organic compound.(1mk)CH3 ClCH2 CHCH2 CHCH CH3(b)1 mole of HBr reacts with propene molecules. Draw the structure and name the compound formed.(2mks)6.The following set-up was used to prepare Carbon (II) Oxide in laboratory.Concentrated sulphuric IV acid Carbon II oxide gas Liquid X Ethane dioc acid (a) Name liquid X and state its value.(2mks)(b) Explain why the gas is collected over water.(1mk)7.Given that:?1C? O→CO? ? ? 395 kJMol( S)2 ( g )12 ( g )c?1→ HO? ? ? 286 kJMolH 2 ( g )? O 2( g)2CH? 5 O→2(l )c?13 CO+ 4 HO? ? ? 2209 kJMol 38(g)2(g)2(g)2(l)cCalculate the enthalpy of formation of propane.(3mks)8.State and explain the observations made when concentrated nitric (V) acid is added to copper turnings.(3mks)Page | 10900Chemistry paper 1, 2&39.Study the Flow chart below and answer the questions that follow.Solid AProcess 1HNO3(aq)ColourlessExcesssolutionNH4OHExcess sodiumhydroxideColourlesssolution(i)Identify the cation and anion present in solid A.(ii)Identify substance: A and BBrown gas Bcolourless gas CWhite solid Dwhen coldColourlesssolution(1mark)(1 mark) 10. The diagram below represents a set-up for the laboratory preparation of oxygen gas. Water gas Solid A (i)Name solid A.(1mk)(ii)Write a balanced chemical equation for the reaction that took place.(1mk)11. Explain why Hydrogen Sulphide is a gas at room temperature while water is liquid at room temperature.(2mks)12.(a) During the extraction of Aluminium, the oxide of metal is dissolved in Molten cryolite before it is electrolysed. Explain.(1mk) (b) Giving reasons, state two uses of Aluminium metal.(2mks)13. State and explain the observation made when coloured flowers are placed into a gas jar full of chlorine gas. Use equations where possible.(3mks)14. A section of a polymer has the following structure.- CH2 - CH - CH2 - CH - CH2 - CH -ClClClA sample of this polymer is found to have a molecular mass of 1500.Page | 11000Chemistry paper 1, 2&3 Determine the number of monomers in the polymer (H = 1, C = 12, Cl = 35.5)(2mks)15.(a) Zinc is extract from calamine, name another ore used to extract zinc.(1mk)(b) Name the reducing agent used in the furnace during extraction of zinc.(1mk)(c) Explain the effect of the by-product of roasting process of zinc ores on the environment.(1mk)16.Xg of sodium hydroxide were dissolved in distilled water to make 100cm3 of solution 40cm3 of this solution required 25cm3of 1M sulphuric (VI) acid. Determine the mass of X of solution of sodium hydroxide (Na = 23, O = 16, H = 1)(2mks)17.Study the table below and answer the questions that follow.Element / IonElectronic configurationK-32,8,8L+12,8(a) Write the formula of the chloride of element K.(1mk)(b) With reason(s) compare the melting point of the chlorides of element K to that of element L(2mks)18.(a) State the Le Chateliars principle.(1mk)(b) Ammonia gas can be prepared as shown:N?3H2NHΔH = - 91kJ/mol.2(g)2(g)3(g)State and explain the observations made if the pressure is increased in the system.(2mks)19.During electrolysis of a sulphate of metal M, using M electrodes, a current of 0.5A was passed through the solution for 12minutes, 52 seconds. The mass at the cathode increases from 2.40g to 2.44g. Determine the charge of metal M (1f = 96500C,M = 20).(3mks)20.When hydrocarbon was completely burnt in air, 2.51g of carbon (IV) oxide and 1.28g of water were formed. Given that thecompound has a relative molecular mass of 58, find its molecular formular (C = 12, H=1).(3mks)21.(a) Nitrogen (II) oxide can be prepared by catalytic oxidation of ammonia. Name the catalyst used in the process.(1mk)(b) State two uses of ammonia.(2mks)22.(a) Flower extracts are oftenly used as indicators in the laboratory. State one disadvantage of using flower extracts asindicators.(1mk)(b) Complete the table below.IndicatorColour inAcidBaseNeutralPhenolphthaleinPinkColourlessMethyl orangePinkOrange23. Study the diagram below and use it to answer the questions that follow. SwitchBulbMolten Lead (II) Iodide Heat(a) Write the equations for the reactions taking place at the:I.Anode(1mk)II.Cathode(1mk)(b) Name one application of electrolysis.(1mk)24. Alkaline earth metals are generally less reactive than alkali metals. Explain.(2mks)25. The diagram below shows properties of radiations. a b c Radioactive SourceSheet of AluminiumLead blockPaperFoilPage | 11100Chemistry paper 1, 2&3 (a) Identify the particles labeled a and b.(1mk(b) State two differences between chemical and nuclear reactions.(2mks)26. Study the diagram and use it to answer the question that follow. Copper (II) Oxid Hydrogen gas Product B Heat (i) State the observations in the combustion tube.(1mk)(ii) Describe the chemical test for product B.(1mk)27. The curves below represent the volume of carbon (IV) oxide gas evolved when 1M concentrated hydrochloric acid and 60g of calcium carbonate and also 0.5M concentrated hydrochloric acid was reacted with the same quantity of the carbonate. QRTime (seconds) (a) Which of the curves represent the reaction of 1M concentrated hydrochloric acid with powdered calcium carbonate.Explain.(1mk)(b) Explain why the curves flatters at the same level of production of carbon (IV) oxide.(1mk)28. The diagram below shows heating curve of water in the laboratory. 1100CE1000CDCBATime (minutes)(i)At what temperature does the water boil?(?mk)(ii) Giving reason(s) is this pure or impure water?(1? mks)(iii) State the effect of impurities on the boiling point of water?(1mk)29. When 0.1g of a certain compound Q was burned and used to heat 150cm3 of water, the temperature rose from 250C to 290C. Calculate the relative molecular mass of the compound given that 1 mole of the compound has an enthalpy of -1072kJ/mol. (S.h.C = 4.2J Kg-1k-1, density of water = 1g/cm3)(2mks)30. Study the flow chart below and answer the questions that follow. Substance DEthaneheat Sodium hydroxide Product Name the substances: C and D Page | 11200Chemistry paper 1, 2&3 NANDI EAST, NANDI SOUTH & TINDERET SUB-COUNTIES JOINT EVALUATION 2016 233/2 CHEMISTRY PAPER 2 THEORY JULY / AUGUST 2016 TIME: 2 HOURS 1.Use standard electrode potentials of elements A, B, C, D and F given below to answer the questions that follow. The lettersdo not represent the actual symbols of the elements.E? volts??A(a q)2?? 2eA( s )-2.90? B+2eB-2.38(aq)( s)??1C? 2eC0.00( aq)?D(a q)1? 2e2?D? F2 ( g)(s )+0.34+2.87 F2(g )? e(aq)2(i) Which element is likely to be hydrogen? Give a reason for your answer.(2mks)(ii) What is the E? value of the strongest reducing agent?(1mk)(iii) In the space provided, draw a labeled diagram of the electrochemical cell that would be obtained when half-cells ofelement B and D are combined.(3mks)(iv) Calculate E? the value of the electrochemical cell constructed in (iii) above.(2mks)(b) Study the diagram below and answer the questions that follow.Gas XGas YHCl gasWaterGraphiteGraphiteSwitchBulbWhen some hydrogen chloride gas is allowed into water and the mixture stirred, the bulb lights and gases X and Y areformed.(i) Name: Gas X(1mk)Gas Y(1mk)(ii) Explain why the bulb does not light before the hydrogen chloride gas is let into the water.(2mks)2.(a) State how burning can be used to distinguish between ethane and ethyne. Explain your answer.(2mks)(b) Draw the structural formula of:(i) Butyne(1mk)(ii) Propanoic acid(1mk)Page | 113 00Chemistry paper 1, 2&3 (c) The flow chart below shows a series of reactions starting with ethanol. Study it and answer the questions that follow.Ethanoic acidProcess AEthanolHeatConc. H2SO4Gas BHigh pressurePolymer(i) NameI.Process AII. Substances B and CNaOHSoda limeCHeatMethane(1mk)(2mks) (ii) Write an equation for the combustion of ethanol.(1mk)(iii) Explain why it is necessary to use high pressure to change gas B into the polymer.(1mk)(iv) State one use of methane.(1mk)(d) Give the names of the following compounds: CH3 (i)CH3 - C - CH3(1mk)CH3 (ii)CH3C = C CH2 CH3(1mk)3.(a) At 250C, 50g of potassium nitrate were added to 100g of water to make a saturated solution.What is meant by a saturated solution?(1mk)(b) The table below gives the solubilities of potassium nitrate at different temperatures.Temperature 0C122028364452Solubility g/100g of water223142557090(i) Plot a graph of the solubility of potassium nitrate (vertical axis) against temperature.(3mks)(ii) Using the graph: I.Determine the solubility of potassium nitrate at 150C.(1mk)II. Determine the mass of potassium nitrate that remained undissolved given that 80g of potassium nitrate were added to100cm3 of water and warmed to 400C.(2mks)(c) Determine the molar concentration of potassium nitrate at 150C.(Assume there is no change in density of water at thistemperature)(K = 39.0; N = 14.0; O = 16.0)(2mks)(d) Starting with aluminium sulphate, describe how a solid sample of aluminium hydroxide could be prepared. (3mks)4.(a) Describe the process by which nitrogen is obtained from air on a large scale.(b) Study the flow chart below and answer the questions that follow.Ammonia(4mks)Nitrogen gasCopperWater Page | 11400Chemistry paper 1, 2&3 (i) Identify gas J.(1mk)(ii) Using oxidation numbers, show that ammonia is the reducing agent in step VI.(2mks)(iii) Write the equation that occurs in step V.(1mk)(iv) Give one use of ammonium nitrate.(1mk)(c)(i) The reaction between Lead (II) Nitrate and concentrated sulphuric (VI) acid starts but stops immediately. Explain.(2mks)(ii) Name one suitable reagent that can be reacted with concentrated sulphuric (VI) acid to produce nitric (V) acid.(1mk)5.Study the following part of periodic table chart and use it to answer the question that follow. The letters are of the actualsymbols of the elements.ASCDEFGHB(a)(i) Which elements form ions with charge of -2. Explain.(1mk)(ii) Compare the ionic radius of C and E. Explain.(2mks)(iii) Write the formular of the compound formed between element G and H.(1mk)(iv) In terms of structure of bonding, explain why the oxides of D has a lower melting point than that of G.(1mk)(v) Write an equation to show the action of heat on nitrates of F and G.(1mk)(b)(i) What is electron affinity?(1mk)(ii) Elements E and H are in the same group in the periodic table. Which of these two elements is most reactive.Explain.(1mk)(c)Study the table below and answer the questions that follow.SubstanceABCDEFMpt 0C801119139-5-1011356113Bpt 0C141044545754-362860Electrical conductivity (solid)PoorPoorGoodPoorPoorPoorElectrical conductivity (liquid)GoodPoorGoodPoorPoorpoor(i)Identify a substance with:(a)Giant metallic structure(1mk)(b)Simple molecular structure(1mk)(ii)Substance A and C conduct electric current in the liquid state. State how the two substances differ as conductors ofelectric current.(2mks)6.The diagram below shows the process of manufacturing sodium carbonate using solvay process. Study it and answer thequestions that follow.(a) Name gases A and B.(2mks)(b) Name liquid C and solid D.(2mks)(c) Write equations of the reactions in:(2mks)Tower P:Chamber R:Page | 11500Chemistry paper 1, 2&3 (d) Name the product T formed at chamber R and give one of its uses.(2mks)(e) Explain using ionic equations how sodium carbonate is used to soften hard water.(2mks)7.(a) Define the standard enthalpy of formation of a substance.(2mks)(b) Use the thermo chemical equations below to answer the questions that follow.71.CH? O2 CO? 3 HO:? H? ? 1860 kJ / mol2. C262? O22( g )2CO:( l )1? H? ? 394 kJ / molgraphite2 ( g )3.H+ 1H2( g )2O? H? ? 286 kJ / mol 2(g)O2(g)2(l)32(i) Name two types of heat changes represent by?H3(2mks)(ii) Draw an energy level diagram for the reaction represented by equation 1.(2mks)(iii) Calculate the standard enthalpy of formation of ethane.(2mks)(c) When a sample of ethane was burnt, the heat provided raised the temperature of 500cm3 of water by 21.5k(specific heat capacity of water = 4.2kJ/kg/k and density of water = 1g/cm3.Calculate the:(i) Heat change for the reaction.(2mks)(ii) Mass of ethane burnt (RFM of ethane = 30).(2mks)Page | 116Chemistry paper 1, 2&3 NANDI EAST, NANDI SOUTH & TINDERET SUB-COUNTIES JOINT EVALUATION 2016 233/3 CHEMISTRY PRACTICAL JULY / AUGUST 2016 CONFIDENTIAL INSTRUCTIONS TO SCHOOLS Each student should have the following:-1.100cm3 of solution B.2.80cm3 of solution A.3.Pipette (25ml)4.Burette (50ml) in a retort stand.5.Methyl orange indicator with a dropper.6.Two conical flasks.7.Filter funnel8.Measuring cylinder (10ml)9.Measuring cylinder (50ml)10.Thermometer (-10 to 1100C)11.100ml beaker preferably plastic.12.Stopwatch / clock13.2 Labels14.100ml Hydrogen peroxide solution D15.50cm3 of solution C.16.50cm3 of solution E.17.30cm3 of starch solution K.18.Liquid P (about 10ml ethanol)19.Wooden splint20.Solid M (1cm piece of magnesium ribbon)21.Test tube rack22.Six test tubes23.Two boiling tubes24.6g of solid L (prepared by mixing ammonium sulphate and aluminium sulphate in the ratio 1:1 i.e. 2g of ammonium sulphateand 2g of aluminium sulphate)25.Pieces of blue and red litmus paper.26.Distilled water in a wash bottle.27.A metallic spatula.28.About 1g of sodium hydrogen carbonate.Students should have access to:-(a)Acidified potassium chromate (VI)(b)Ethanoic acid(c)1M sulphuric (VI) acid with a dropper(d)Source of heat(e)1M barium nitrate solution with a dropper(f)1M nitric acid(g)1M lead II nitrate with a dropper(h)1M ammonia solution with a dropper(i)1M potassium iodide solution with a dropperNOTE: HOW TO PREPARE SOLUTIONS?Hydrogen peroxide is prepared by measuring accurately using a clean measuring cylinder 100cm3 and 100 volume ofhydrogen peroxide and add 900cm3 of distilled water to make a litre of solution.?Potassium iodide is prepared by weighing accurately 8.3g and dissolve in 200cm3 of distilled water and make the mark to 1litre of solution.?Sodium thiosulphate (Na2S2O3) 0.1M is prepared by weighing accurately 15.8g and dissolve in 200cm3 of distilled water andmake the mark to 1 litre.?Solution B is 1M HCl.?Starch solution is papred by dissolving 20.0g of starch powder in 100cm3 of distilled water.?Solution A is prepared by mixing 53g of sodium carbonate and 42g of sodium chloride and dissolved in one litre of distilledwater.?Solution B is 1M hydrochloric acid.Page | 11700Chemistry paper 1, 2&3 NANDI EAST, NANDI SOUTH & TINDERET SUB-COUNTIES JOINT EVALUATION 2016 233/3 CHEMISTRY PAPER 3 PRACTICAL JULY / AUGUST 2016 TIME: 2 ? HOURS 1.(I) You are provided with:-?Solution A containing 95g of a mixture of sodium carbonate and sodium chloride per liter of solution.?Solution B which is 1MHCl.You are to determine the percentage of sodium carbonate in the mixture. Proceed as follows: Pipette 25.0cm3 of solution A and transfer it to the conical flask. Titrate it with solution B from the burette using 3 drops of methyl orange indicator. Stop titrating when a permanent pink colour appears. Repeat the experiment and complete the table below. TABLE I IIIIIIFinal burette reading (cm3) Initial burette reading (cm3) Volume of B used (cm3) (4mks) (a)Determine the average volume of solution B used. Show your workings.(1mk)(b)Determine the number of moles of B used.(1mk)(c)Determine the number of moles of the base used.(1mk)(d)Calculate the concentration of sodium carbonate in mol dm-3.(1mk)(e)Determine the mass of sodium carbonate in 1 litre of the solution (Na = 23, C = 12, O = 16)(1mk)(f)Determine the percentage of sodium carbonate in the mixture.(1mk)(II) You are provided with the following:--Hydrogen peroxide labeled solution D-Dilute Hydrochloric acid labeled solution B-Sodium thiosulphate labeled solution C-Potassium iodide labeled solution E-Starch solution labeled solution K-Distilled water in a wash bottleYou are required to determine how the rate of reaction of hydrogen peroxide with potassium iodide varies with the concentration of hydrogen peroxide. Procedure Experiment 1 Using a burette, place 25cm3 of solution D into beaker 1. Into the same beaker, add 20cm3 of solution B using a 50ml or 100ml measuring cylinder. Shake the contents of beaker 1. Using a 10ml measuring cylinder, place 5cm3 of solution C into beaker 2 followed by 5cm3 of solution E then 2cm3 of solution K. Shake the contents of beaker 2. Pour the contents of beaker 2 into beaker 1 and start a stop clock / watch immediately. Swirl the mixture and let it stand. Note the time taken for the blue colour to appear. Record the time in the space provided for experiment 1 in the table below. Clean beaker 1. Repeat the procedure with the volumes of water, solutions B, C, D, E and K as shown in the table for experiments 2 to 5. 1(a) Complete the table by computingTimeSec-1(5mks) ExperimentVolume ofVolume ofVolume of diluteVolume ofVolume ofVolume ofTime (sec)1water(cm3)hydrogensulphuric acid, solutionsodiumpotassiumstarch solution,Tim eperoxide,B (cm3)thiosulphate,iodidesolution KSec-1solution DsolutionC (cm3)solution E(cm3)(cm3)(cm3)10252055225202055231015205524151020552520520552Page | 11800Chemistry paper 1, 2&3(b)Plot a graph of1TimeSec-1 (y-axis) against volume of hydrogen peroxide used in solution A.(3mks) (i)From your graph, determine the time that would be taken if the contents of beaker 1 were: 17.5cm3 water, 7.5cm3 solution Dand 20cm3 solution B.(2mks)(ii)How does the rate of reaction of hydrogen peroxide with potassium iodide vary with the concentration of hydrogen peroxide?(1mk)2.You are provided with liquid P. Carry out the tests on the liquid to determine its content.(b)Place about 1cm3 of P in a test tube; drop a piece of magnesium, solid M.ObservationsInferences(1mk)(1mk)(c)Place a drop of liquid P on the back of your hand and blow over it.ObservationsInferences(1mk)(1mk)(d)Divide the remaining liquid into two portions.(i)To the first portion add three drops of acidified potassium chromate (IV). (K2Cr2O7)ObservationsInferences(?mk)(?mk)(ii)To the 2nd portion, add equal volume of ethanoic acid followed by three drops of concentrated sulphuric (IV) acid and boil themixture.ObservationsInferences(?mk)(?mk)3.You are provided with solid L. Carry out the tests and record your observations and inferences.(a)Take a spatula full of solid in a clean dry boiling tube and heat gently then strongly.ObservationsInferences(1mk)(1mk)(b)Place the remaining solid L in a clean boiling tube and add about 10cm3 of distilled water. Divide the resulting product intofour portions.ObservationsInferences( ? mk)( ? mk)(i)To the first portion, add 1cm3 barium nitrate solution.ObservationsInferences(1mk)(1mks)(ii)To the second portion, add 1cm3 of nitric (V) acid followed by lead (II) nitrate.ObservationsInferences(1mk)(1mk)(iii) To the third portion, add excess ammonia solution.ObservationsInferences( ? mk)( ? mk)(iv) To the fourth portion, add 1cm3 of potassium iodide solution.ObservationsInferences( ? mk)( ? mk)(v) To the fourth portion, add a spatula full of sodium hydrogen carbonate powder.ObservationsInferences(1mk)(1mk)Page | 11900Chemistry paper 1, 2&3 NANDI EAST, NANDI SOUTH AND TINDERET SUB-COUNTIES JOINT EXAMINATIONS 2016 233/1 CHEMISTRY PAPER 1 MARKING SCHEME 1.(i)Charred part (ii)- Visible when carrying out experiment. √?- Do not react with most reagents. √?2.(a) Atomic number is the number of protons in an atom while mass number is the sum of protons and neutrons in an atom.(b)(i) Number of electrons=Number of protonsProtons=37 - 20=17√?(ii) Group VII√? has seven electrons in the outermost shell. √?3.ZnO?2HCl√?→ZnCl+HO√?(s)(aq)2(aq)2(l)Identifying reagent √?(and any other acid i.e. HNO3 or H2SO4(aq))ZnO?2NaOH√?→NaZnO+HO√?22(aq)2(l)Identifying NaOH or KOH1mk for the equation (balanced)4.(a) States that when gases reacts they do so in volumes that bear a simple ratio to one another and to volumes of the productif gaseous, temperature and pressure remains constant.(b)CH?3O→2CO+2HOxy(g)2(g)2(g)2(l)75cm3225cm3150cm3 150cm3√?1V3V2VNo. of oxygen atoms of L.H.S. = 6?there are 2 water molecules, volume of steam produced = 150cm3√?Cx=2COx=2-√?Hg=4ltg=4√?Cxformula C2H4√?5.(a)5 - Chloro - 4 - Methyl Hex-l-ene. √1(b)HBrH|||award 1mk for structureH CC C =H√1award 1m for correct name|||HH H2 - Bromo propane √1 6. (a) Sodium hydroxide / potassium hydroxide. √1 - To absorb carbon (IV) oxide gas. √1 (b) Because it is slightly soluble in water. ? ?7.3C +4H22O23O2? HC? HC? ? 395H fC3 H8√15O2?1?1? ? 286 kJmol? H? ? ? 2209 kJmol?1kJmol3 CO? 4 H O 22(l)Page | 120 00Chemistry paper 1, 2&3? H? ? ? ?f ( C H ) ? ? H C ( C H )=? H C( H) ? ? H C (C )? H? H38?f ( C 3 H 8 )?f ( C 3 H 8 )?382? ? 2209=3( ? 395 kJmol? 2209 ? ( ? 1185 ) ? ( ? 1544 )=2209 - 2729? 1?1?1) ? 4( ? 386 kJmol ) √18.? H f=? 520 kJmol √1- Blue solution formed. √?- Brown fumes. √?- HNO3 is a strong oxidizing agent, it oxidizes copper metal to CU2+ ions (blue)√1 and itself is reduced to Nitrogen IV oxide gas (brown) √12? ?9.(i) Cation -Znion√1(ii) B - Nitrogen (IV) oxide gas. √?C - Oxygen gas√?10.(i) Sodium peroxide√1(ii)Na O? HOAnion -NO 3 ion√12 NaOH? O√1 22(s)2(l)(aq)2(g)11.Water has both Vander Waal forces and Hydrogen bonds while Hydrogen sulphide has Vander Waal forces only betweenmolecules. √1 Hydrogen bonds are stronger than Vander waal forces. √112.(a) To lower the Melting point of Aluminium oxide from 20150C to 8000C. √1(b)- An alloy of Aluminium is used in making parts of aeroplanes, trucks, trains, buses√? because they are light, hard andstrong. √?-For making cooking vessels√? because they are not easily corroded since they are unreactive.-Making overhead cables√? because they are light and good conductors of electricity. √?(any two @ 1mk = 2mks)13.Coloured flowers are decolourized. √1Cl?HO→HoCl?HCl√12(g)2(l)(aq)(aq)SunlightHoCl→HCl ??O?√?When mixed with coloured flowers the free oxygen combines the dye to form colourless matter.HoCl (aq)? Dye→ Hcl? Colourless matter√?(aq ) 14.Monomer CH2=CH(Cl)Mass of the monomer=(2x12) + (1x3) + (1x35.5)=24 + 3 + 35.5=62.5√1(62.5)n=1500√?n=24√?15.(a) Zinc blende √1(b) Carbon / Carbon (II) Oxide(c)- It causes acid rain which affect both plants and animals. √1- SO2 causes respiratory problems.- SO2 causes fog which reduces visibility posing threat to motorists. √1 (any 1 mark)16.1 mole→100cm3?→25cm3MolesH2 SO425 ?1=0.025 moles√?10002NaOH?HSO→NaSO?HO(aq)2424(aq)2(l)Mark ratio 2:1Moles of NaOH = 0.025 x 2 = 0.05√?0.05 moles→40cm3?→100cm3005?10040=0.125 moles√? RFM of NaOH=23 + 16 + 1 = 40Mass=0.125 x 40=5g√?17.(a) KCl3 / KCl5(b) L has higher melting point than K. L has giant ionic structure with electrostatic force while K has simplemolecular with weak vander waal forces.18.(a) When a system in equilibrium√1 is subjected to change, the system adjust so as to oppose that change.Page | 12100Chemistry paper 1, 2&3 (b) More ammonia is formed√? / forward reaction√? is favoured hence equilibrium shift from left to right.√?19.Q= It= 0.5 x 772 = 386CMass of M sulphate deposited=0.04g→ 3.8620g→ ?20 g ? 386 √? =193,000C0 041F→ 96500C?→ 193000C1 ? 193000 C=2F96500 CCharge: +2orM ?220.12=0.6845 √?2.44 - 2.40 = 0.04g√?MF= ? C? =C√?44218? 2 51? 1 28=0.1422CH2 H 524 H 10√? 0684501422√?121005 701422005 7005 71x22.5x2√?25?C2H5?n?58√?29 n=58n=2292921.(a) Platinum rhodium(b)- Manufacture of nitrogenous√1 fertilizers.- Softening water√1- Refrigerant e.g. in warehouse, √1 ships.22.(a) They give inconsistent results when used.(b)- Phenolphthalein - colourless√? in acid.- Methyl orange - yellow√? in base.23.(a) Anode(I)2I?→I2?2e(aq)(s)Cathode? 2(II)Pb+2e→Pb(aq)(s)(b)- Extraction of reactive metals such as sodium.- Purification of metals - Electroplating metals - Manufacture of pure chemicals e.g. Cl2, NaOH.(any one @ 1mk)24.Alkaline earth metals react by losing√? two electrons while alkali metals lose one. √? Losing the two electrons for alkalineearth metals requires a lot√? of energy than in alkali metals which loses one. √?25.(a) a - Beta particle √?b - Alpha particle √?(b) Chemical reactionNuclear reaction- Takes place in the valence electrons- Takes place in the nucleus i.e. protons / neutrons- Heat energy released is less- Heat energy released is more- Affected by environmental factors e.g. temperature - Not affected by environmental factors26.(i) Black Copper (II) oxide√? turns brown. √?Colourless vapours condenses on cooler parts. √?(ii)- Insert Cobalt (II) Chloride paper into product B.-Cobalt (II) Chloride turns to pink from blue or-Add product B into anhydrous copper (II) sulphate.-Anhydrous copper (II) sulphate turns to blue.(any one @ 1mk = 1mk)27.(a) Q√? - 1MHCl is highly concentrated√? therefore it takes shorter time for a reaction to reach completion.(b)- Same quantity of calcium carbonate will have reacted with both 0.5M HCl and 1M HCl hence same volume of CO2will be produced.28.(i)100 - 1100C(ii) Impure√? - it melts and boils over a range of temperature. √?(iii)- Increases the boiling point. √1Page | 12200Chemistry paper 1, 2&3 29.29 - 25 = 40C150√?10000.1g?0 1?? 42 ? 4? 252 k J2 52kJ1072 kJ1072 √? =42.54√? 25230. C - Sodium propanoate√1D - Sodium carbonate √1Page | 12300Chemistry paper 1, 2&3 NANDI EAST, NANDI SOUTH AND TINDERET SUB-COUNTIES JOINT EXAMINATIONS 2016 233/2 CHEMISTRY PAPER 2 MARKING SCHEME 1.(a) i)Element C; √1Hydrogen is used as the reference√1 electrode hence Eθ is 0.00V.ii)-2.90V √1iii) (iv) 0.34 - (-2.38) = 2.72V√? (b) (i) Gas X - Oxygen√1 Gas Y - Hydrogen√1 (ii) Water is a poor electrolyte. √1 When hydrogen chloride gas dissolves in water, it forms ions making it a strong electrolyte. √? 2.(a) Ethane burns with non-luminous√?/ blue flame while ethyne burns with a smoky / yellow / sooty flame; this isbecause ethyne is highly unsaturated while ethane is saturated.(b)HH||H CCC = C||HHBut-i-ene(c)(i)I.Oxidation√1II.Bethene√1C - Sodium ethanoate √1(ii)CH CHOH? 3 OHH||OH| |H CCCOH||HHPropanoic acid→ 2 CO? 6 HO√1 32(l)2(g)2(g)2(l)(iii)To bring the reacting particles in close contact for the reaction to occur.(iv)Methane is used-As a fuel-Manufacture of carbon black used in printing ink-Making paint and paint ink(d)(i)2,2 dimethyl propane / dimethyl propane(ii)Pent-2-yne3.(a) A solution which cannot dissolve any more solute at a particular temperature. √1(b)I.25g for 100g of water√? (graph √?)II.Mass dissolved = 62g√? (graph √?)Mass undissolved =80 - 62 = 18g(graph √?)Page | 12400Chemistry paper 1, 2&3 (i) A graph of solubility of potassium nitrate (vertical axis) against temperature. Scale - ? mark - Both axes, the scale should occupy more than ? of the plotted. (ii)Axes ……………… ? markLabeling of both axes with the units.(iii)Plotting ………….. 1 mark5 - 6 correctly plotted points - award 1mk2 - 4 correctly plotted points - award ? mkBelow 2 points correctly plotted points award 0mk(iv)Shape of the graph …..1mk(c) R.F.M. of KNO3=101Moles of KNO3 in 100g=25 = 0.2475101Moles of 1000g pf water=02475?1000=2.475M100(d) Add aqueous ammonia to form 100 aluminium hydroxide, filter and dry in a desiccator at low temperatures.4.(a)- Filter√? the air / electrostatic precipitation / purify√? the air.-Pass air through sodium hydroxide√? or KOH to remove CO2. √?-Cool to -250C√? to remove water vapour.√?-Cool the remaining gases to form liquid√? air at -2000C.-Perform fractional√? / distillations of liquid air at -2000C.-Nitrogen is collected at -1960C.(b)(i) NO orNitrogen (II) oxide(ii)4NH?3CuO→2N?3HO?3Cu3(g)(s)2(g)2(l)(s)-Oxidation number of N in ammonia increases from -3 to 0.-Oxidation number of reducing agent increases hence ammonia is the reducing agent.-Oxidation number of Copper (Cu) decreases from +2 to 0 hence an oxidizing agent.(iii)NHNO→NO?2HO√1(c)5.(iv)(i)(ii) (a)(ii)43( s)2( g)2(g )- Used as a nitrogenous fertilizer.- Manufacture of explosives.(any 1 for 1mk)The reaction produces insoluble lead (II) sulphate which coats the surface of lead (II) nitrate[Pb(NO3)]Sodium nitrate. √1(i) A or D√?E has got smaller atomic radius than C, because across the periodic there is an extra-added nuclear√1 chargein the nucleus which strongly pull the valence electrons in E in C, thus reducing it s atomic radius. √12? 1 (iii)G? ? HGH2√?Page | 12500Chemistry paper 1, 2&3 (iv)Oxide of D has a weak covalent√? bond within its structure, with simple molecular structure, √? while thatof G has strong ionic√? / Electrovalent bond with Giant ionic structure. √?(v)F N OheatF N O?O√?3( s )G ( N O)heatG O2( s )2( g )? 2 N O? O√? 3( s)2(s )2(g )(b)(i)The minimum energy required by a neutral√? atom to gain electron(s) in gaseous state.(ii)Element E√? this is because it has the highest electron affinity. √?(c)(i)(a)C;(b)D√1(ii)It exhibits allotrophy√1(iii)A - conducts due to movement of delocalized / free ions √?C - conducts due to the movement of delocalized electrons√? 6.(a)(i) A - Carbon (IV) oxide√1B - Ammonia √1(b)C - Ammonium chloride solution√1D - Sodium hydrogen carbonate√1(c) P -N a C l?N H?C O?HO→NaHCO?NHCl( aq )3 ( aq )R -2 N HC l? C a ( OH )2( g )2( l )3( s )4( aq )→ CaCl? 2 NH? 2 HO4( a q )2( a q )2 (aq )(d) Calcium chloride √1Uses-Drying agent-Lower melting point during extraction of sodium.2 ? 2 ?3(g)2(l) (e)CO?CaCaCO√13(aq)(aq)3(s)2?2?OrCO3(aq)?MgMgCO3(s)22?Ca? ?Mgions that causes hardness are precipitated as insoluble carbonates. √17.(a) This is the energy change that occurs when a substance is formed from its substituent elements.(b)(i)-Enthalpy of combustion of hydrogen gas.(1mk)-Enthalpy of formation of water.(1mk)ii)(iii) ?Hf??H1??H2??H2?Hf??H??H??H231= 2(-394) + 3(-286) - (-1860) = +214kJ/mole(c)(i)? H ? mC ? T=? 500? kg x 4.2kJ/kg√1 / k x 21.5k?? 1000? ? =45.15kJ√1(ii)30g of ethane evolves 1860kJg …………………….4515 kJ=30g?4515√11860k J=0.7282g√1Page | 12600Chemistry paper 1, 2&3 NANDI EAST, NANDI SOUTH AND TINDERET SUB-COUNTIES JOINT EXAMINATIONS 2016 233/3 CHEMISTRY PAPER 3 MARKING SCHEME 1.TABLE 1(5mks)(a)Complete table(1mk)(i) Complete table with 3 titres(1mk)(ii) Incomplete table with 2 titres consist value.(1mk)(iii) Incomplete table with inconsistent value(1mk)Penalties-Unrealistic burette reading-Arithmetic error-Inverted tableNB: Penalize ? mark each to a maximum of(? mk)(b)Use of decimal - 1mk-Award 1mk if all values in row 1 and 2 are consistently to 1d.p or 2d.p .-If to 2d.p the last digit be zero or five.-Otherwise award zero-Accept the inconsistency of zero.(c)Accuracy(1mk)-Tied to the school value(1mk)-Check any of the titre readings(i) If any of them is within +0.1 from S.V award 1mk(ii) If within +0.1 from S.V ….(iii) If outside +0.1 unit award zero(d)Principle of averaging(1mk)(i) If 3 constant values, averaged(1mk)(ii) If only two are consistent and averaged(1mk)(iii) If 3 are possible but only averaged(0mk)(iv) 3 inconsistent averaged(0mk)Conditions and penalties (i) The answer should be at least 2d.p unless if divides exactly. (ii) If the average values gives more than 2d.p but the candidate rounds off to 1d.p or less penalize ? mk for the answer. (iii) Penalize ? mark for any unit if given. (e)Final answer(1mk)pare the candidate?s average value wit the school?s value once more.(i) If within +0.1cm3 of S.V …..(1mk)(ii) If within +0.2cm3 of S.V ….(?mk)(iii) If inside +0.2cm3 award(0mk)Note(i) If arithmetic error was made correct for the student average for him and award accordingly(ii) Likewise if wrong value were average choose the correct values, average and award accordingly.ii. No. of moles ofM 2?ans (a ) ? 1√? =1000correct answer√? (1mk) ?2?iii.2H?CO→HO?CO(aq)32Moles of base = ? x ans(b)=iv. Concentration=v. Mass of Na2CO3 = 106 x ans(d) = Correct answer√vi. Mass of Na2CO3 = ans(e) % of ans ( e) ? 100(l)2( g)correct answer √a n sw er (c ) ? 100025√(1mk)= correct answer√ (1mk)(1mk) Na2CO3?95 NB: From (b) to (f) allow an error of +2 unit in the 4th digit. Procedure II A. Complete table-2mks(i) Complete table with 10 readings …….. 2mks (ii) Incomplete table with 5 time readings and 4 or 3 correct rates, 1? mks (iii) Incomplete table with 4 or 3 time readings and 4 or 3 correct rates, 1? mk (iv) Incomplete table with 4 or 3 time readings and 2 correct rates…(1mk) (v) Incomplete table with 2 time readings and 2 correct rates, ? mk Page | 12700Chemistry paper 1, 2&3 (vi) Incomplete table with less than 2 time readings …………. 0mks Penalties (i) Penalize ?mk ONCE for unrealistic time values i.e. below 10 or more than 170 seconds. (ii) Penalize ? mk ONCE for time reading in minutes. (iii) Penalize ? mk ONCE for wrong arithmetic in the rate if error is outside +2 units in the 3rd decimal place. (iv) Rate should be given to at least 3 decimal places unless it works out exactly otherwise penalize ? mk ONCE for rounding off to 2d.p. Note (i) Reject fractions for 1 and mark accordingly. t (ii) If fractions appear followed by an extra row of decimals, accept and award accordingly. (iii) Accept rates expressed in standard form. B.DECIMALS ….. 1mk(Tied to time row only)?Accept either whole numbers or 1 or 2 decimal points used consistently, otherwise penalize fully.C.ACCURACY ………. 1mk?Compare the candidates first time reading to the school value (S.V).?If within +2 seconds of the S.V, award 1mk otherwise penalize fully. S.V. is the teachers 1st time reading.D.TREND ……… 1mkAward 1mk for reading increasing continuously otherwise penalize FULLY.Graph(a)Labelling - ? markAccept labeling even if no units are shown. Penalize fully if wrong units are used.(i) Penalize FULLY for inverted axes.(ii) Penalize FULLY if only one axes is correctly labeled.(b)Scale?Area covered by the actual plots must be at least ? of the grid.?Scale interval must be consistent in each of the axes. Scale chosen must accommodate all plots.NOTE: Award for scale even if the axes are inverted.(c)Plotting - 1mk(i) If 4 or 5 points correctly plotted-1mk(ii) If 3 points correctly plotted -?mk(iii) If less than 3 points - 0mk(iv) If scale interval changes, mark the plots if any within the 1st correct intervals and award accordingly.(v) Accept correct plots even if the axes are inverted.(d)Line-Accept a straight line passing through at least two points correctly plotted and through the ORIGIN on extrapolation.1 II.(a) Correct showing ofon the graph …………..? markt - Stating correct reading …………………….? mark1t ?correctval ue√? = correct answer (b) Rate of reaction increases with increase in concentration of hydrogen peroxide … (1mk)Page | 12800Chemistry paper 1, 2&3 TABLE II(c) Complete the table by computingExperimentVolume ofVolume ofwater(cm3)hydrogenperoxide,solution D(cm3)10252520310154151052051Sec-1TimeVolume of diluteVolumesulphuricacid,sodiumsolution B (cm3) thiosulphate,solution(cm3)205205205205205(5mks)ofVolume ofVolume ofTime1potassiumstarch(sec)iodidesolution,TimeCsolutionEsolution KSec-1(cm3)(cm3)52240.04252300.03352370.02752520.01952680.015 2.(a)ObservationsInferences? Effervescence / bubbles of a colourless gas produced.R-OH, - COOH√1OR? REJECT; OH or -OH? Colourless gas√? which extinguishes or puts off aAward zero for any contradiction i.e. double or tripleburning splint with a pop sound. √?bonds.NB:- Award half mark for bubbles burns with a pop sound.- Award 0mark for pop sound produced.(b)ObservationsInferencesLiquid feels cold√? and evaporates faster. √?R-OH or ROH√1Reject OH or -OH(c)(i)ObservationsInferencesOrange acidified K2Cr2O2 turns green. √1ROH or R-OH√1NB: Original colour must be given to earn mark.(ii)ObservationsInferencesSweet / fruity / pleasant smell compound formed. √1ROH or R-OH√13.(a)ObservationsInferences? Red litmus paper turns blue, on strong heating blue litmus paper (both) turned red√? finally decolourized. √??? NH 4 √? mk2? 2 ? ?SO,SO√? mkNB: Accept for ? mk a gas with an irritating smell and credit fully34its corresponding inference.(b)ObservationsInferencesWhite solid dissolves forming a colourless solution //Soluble salt // absence of coloured ions i.e.2? 3? 2? colourless solution formed. √?Fe,Fe,Cu√?(i)ObservationsInferencesWhite ppt. √? CO2 ?3, SO2 ? 2 ?4, SO 3 NB: For all 3 given - 1mk ? Only 2 given - ? mk ? One given - 0mk ? Reject inferences in words Page | 12900Chemistry paper 1, 2&3 (ii) ObservationsInferencesWhite ppt√1SO2?4 √1 Reject any other inference(iii)ObservationsInferences2?2?3?White insoluble ppt formed. √?Mg,Pb,AlNB: All three - 1mk? Any two - ? mark? Only one - 0 mark(iv)ObservationsInferences2?3?No yellow ppt. √?Mg, Alpresent.2?OrPbabsent,? Any two - ? mark? Only one - 0 mark(v)ObservationsInferencesEffervescence / bubbles of a colourless gas produced. √13?Or a gas which turns moist blue litmus paper red or a gas which puts off a burning splint.Alconfirmed.3?NB: to award a mark Almust have beeninferred in (iv) above. Page | 13000Chemistry paper 1, 2&3 M O K A S A J O I N T E X A M I N A T I O N Kenya Certificate to Secondary Education CHEMISTRY PAPER 1 233/1 CHEMISTRY Paper 1 Time: 2 hours 1.Explain the following:(i) It is always advisable to scoop chemical substances using a clean spatula.( ? mark)(ii) Flammable substances should always be kept away from flames in the laboratory.( ? mark)2.Name one reagent that can be used to distinguish between Al3+ and Zn2+ ions in solution and state what would be observed ifeach of the ions is treated with the reagent you have named.(3 marks)3.Manganese sulphide reacts with acids according to the following equation.( )()(aq)+( )()State, giving a reason what would happen to the equilibrium if;(i) Water is added to the equilibrium mixture.(1 ? marks)(ii) Hydrogen chloride is bubbled into the equilibrium mixture.(1 ? marks)4.Use the thermochemical equations below to answer the questions that follow.()()( )( )()()()()(i) Draw an energy cycle diagram to show the enthalpy of formation of ethane.(1 ? marks)(ii) Calculate the enthalpy of formation of ethane.(1 ? marks)5.State the conditions under which copper reacts with sulphuric acid and give an equation for the reaction.(2 marks)6.When 8.8g of hydrocarbon Z was burnt in excess air, 14.4g of water and 11.95 dm3 of carbon (IV) oxide were obtained ats.t.p. Determine the empirical formula of Z.(3 marks)7.Perspex is a synthetic polymer of formulaCH3CH2CnCOOCH3(a) Write the structural formula of the monomer of Perspex.(1 mark)(b) State the type of polymerization involved in the formation of perspex.(1 mark)8.When zinc granules are dropped into two separate solutions of dilute sulphuric (VI) and concentrated sulphuric (VI) acid,effervescence of a colourless gas occurs in each case. Give equations to represent the reactions that take place.(2 marks)9.Study the chart below and answer the questions that follow.MoistureBrown SolidSolid QAdd solid NHeatAdd diluteoxygenXBubble gas P throughBlack Solid ZColourlessH2SO4gas PCuSO4(aq)ppt W(a) Identity solid X.(1 mark)(b) Write an ionic equation for the reaction between P and copper (II) sulphide solution.(1 mark)c) State the observation made when gas P is bubbled through iron (III) chloride solution.(1 mark)10. Use the nuclear equations below to answer the questions that follow.Page | 131 00Chemistry paper 1, 2&3 (i) (ii) (a) Give the actual names of particles X and Y.(1 mark)(b) Give the name of a radiation whose emission does not change the mass number or the atomic number of a radioisotope.(1 mark)11. The structures below represent two cleaning agents M and P.MPWhich cleaning agent would be most suitable for use with water containing calcium sulphate. Give a reason.(2 marks)12.You are given the following half equations:()( )()( )(i) Obtain an equation of the cell reaction.(1 mark)(ii) Calculate thevalue for the cell.(1 mark)(iii) Give the oxidizing species.(1 mark)13.Using dots (?) and crosses (×) to represent outermost electrons; draw diagrams to show bonding in:(a) Aluminium chloride.(1 ? marks)(b) Sulphuric (IV) oxide.(1 ? marks)14.Use the information in the table below to answer the questions that follow.Melting pointElementAtomic number97.8R11660S131440T14-40.1U1763.1V19(a) Write the electron arrangement of:(1 mark)(i) ion of S(ii) atom of T(b) Explain why the melting point of T is higher than that of U.(2 marks)plete the table below.(3 marks)MetalAluminiumLeadSodiumChief oreBauxiteRock saltChemical nameMethod of extractionreduction16.The diagram below represents a set up used for the large scale manufacture of hydrochloric acid.Water Glass beads Hydrochloric acid Dry chlorine gas X Page | 13200Chemistry paper 1, 2&3 (a) Name substance X.(1 mark)(b) What is the purpose of the glass beads?(1 mark)(c) Give one use of hydrochloric acid.(1 mark)17. Calculate the volume of nitrogen (I) oxide produced when 38.2g of ammonium nitrate is completely decomposed by heating(at s.t.p).(N = 14, H = 1, O = 16)(3 marks)18. Give equations to show the reactions that take place when;(a) iron reacts with steam.(1 mark)(b) Give one industrial use of the gas produced in the reactions in (i) and (ii) above.(1 mark)19.(a) When magnesium metal is burnt in air, it reacts with both oxygen and nitrogen gases giving a white ash.Write two equations for the reactions that take place.(2 marks)(b) Give the total number of atoms present in the gas produced when water is added to magnesium nitrate.(1 mark)20. The graph below shows the behavior of a fixed mass of a gas at constant temperature. Pressure (atmosphere) Volume (litres) (a)What is the relationship between the volume and the pressure of the gas?(1 mark)(b)60 cm3 of oxygen gas diffused through a porous partition in 50 seconds. How long would it take 60cm3 of sulphur (IV) oxidegas to diffuse through the same partition under the same conditions? (S = 32.), O = 16.0)(3 marks)21.State and explain the observation made when a moist red litmus paper is put in a gas jar of dry chlorine gas.(2 marks)22.(a) When extingishing a fire caused by burning kerosene, charbon (IV) oxide is preferred to water. Explain.(2 marks)(b) Write the formula of the oxide of carbon which is ?silent killer?.(1 mark)23.Explain why chlorine is a gas while iodine is a solid at room temperature.(2 marks)24.Apart from their location, state any two differences between a proton and an electron.(2 marks)25.What term is given to: The amount of energy given out when a neutral atom in gaseous state gains an electron?(1 mark)26.A certain fertilizer is suspected to be containing nitrate ions. Describe how the presence of nitrate ions can be determined insuch fertilizer.(3 marks)27.Write balanced chemical equations to show the action of heat on the following nitrates.(a) Lead (II) nitrate(1 mark)(b) Silver nitrate(1 mark)28.What is an amphoteric oxide?(1 mark)29.Starting with zinc carbonate solid describe how zinc hydroxide can be prepared in the laboratory.(3 marks)30.Below is a scheme of some reactions starting with but-z-yne. Study it and answer the questions that follow.CH3CClCCICH3 Reagent Y CH3C C CH3HClSubstance QPt + Reagent X Conc.Substance TH2SO4CH3CHCHCH3 Page | 133Chemistry paper 1, 2&3 (a) Name Y, X and T(1 ? marks)(b) Give the name of the following organic compounds.(? mark)(i)H OH CCOHH(ii)H H OH HH CCCOCCHH HH H(iii)H OH CCONaH31. The following results were obtained during an experiment to determine the solubility of potassium nitrate in water at 30 0C.Mass of dish = 15.86g, mass of dish + saturated solution at 300C = 26.86g, mass of dish + solid KNO3 after evaporation todryness = 16.7g. Calculate the mass of saturated solution containing 60.0g of water at 300C.(3 marks)Page | 13400Chemistry paper 1, 2&3 MOKASA JOINT EVALUATION EXAM K. C. S. E. (Kenya Certificate of Secondary Education) 233/2 CHEMISTRY Paper 2 Time: 2 Hours 1.The grid below shows part of the periodic table. Use it to answer the questions that follow. (The letters do not represent theactual symbols.)SUPRTWQ a)Which of the above elements has the largest atomic radius? Explain?(1 mark)b)Identify the most reactive non-metal. Explain(1 mark)c)Write the electron configuration of ions of;(i) Element S(? mark)(ii) Element Q(? mark)d)Compare the atomic radius of P and R(1 mark)e)Write the formula of one stable cation with an electron arrangement of 2:8(1 mark)f)Given that the atomic mass of W is 40 write down the composition of its nucleus(1 mark)g)Write the formula of the compound formed when P and S react(1 mark)h)Give the family to which element R belong(1 mark)i)Element X forms an ion with the fomula X3- with electron configuration of 2.8. On the grid above, show the position ofelement X(1 mark)j)Compare the electrical conductivity of the compound formed between P and U and element Q(2 marks)2.Study the flow chart below and answer the questions that follow.C3H8Step(viii)C3H7Cl+HClCl2 and UV light Step I CH3 CH3CH=CH2Step IIIC - CH2 nStep IIPropanoicPotassium metalX + Gas MacidStep VICH3CH2CH2OHStep VIIStepConc.Step IVVIH2SO4 + Ethanol+ heatSugars a) i) Name the type of reaction in the following stepsStep I(1 mark)Step IV(1 mark)ii) Name the important reagents and conditions in;Step I:(? mark)ReagentPage | 13500Chemistry paper 1, 2&3 Condition. Step V:(? mark)Reagent(? mark)Condition(? mark)b)Name and draw the structure of compound L(2 marks)c)Write an equation for the reaction in Step VII(1 mark)d)State the homologous series to which the compound C3H8 belongs(1 mark)e)State one industrial application of the process in Step I(1 mark)f)Explain how one can distinguish between the compounds C3H8 and C3H6 using a chemical test(2 marks)3.The following information show standard electrode potentials for some half reactions. Use it to answer the questions thatfollow.E?/VoltsCe4+(aq) + e-→ Ce3+(aq)+1.61Fe3+(aq) + e-→ Fe2+(aq)+0.77I2(aq) + 2e-→2I-(aq)+0.54Fe2+(aq) +2e-→ Fe(s)-0.44Zn2+(aq) + 2e-→ Zn(s)-0.76J3+(aq) + 3e-J(s)Xa)Identify the strongest reducing agent(1 mark)b)Which substance in the table is suitable to oxidize iodide ions to iodine?(1 mark)c)Study the cell representation below and answer the questions that follow.Zn(s) /Zn2+(aq) // KNO3 Fe2+(aq) /Fe(s)(i)Identify the anode and the cathodeAnode:(1 mark)Cathode:(1 mark)(ii)If the two half cells in c(i) above are connected externally, write an equation taking place in zinc half cell(1 mark)iii)Calculate the e.m.f. of the cell(1 mark)iv)State the role of KNO3(1 mark)v)Explain what happens when KCl(aq) is used instead of KNO3 in a case where Pb(s)/Pb2+(aq) is one of the half cells(2 marks)vi)Draw an electrochemical cell to represent the cell in c(ii) above(2 marks)vii)If the e.m.f. of the cell J(s)/J3+(aq)//I2(s)/2I-(aq) is +1.32V, calculate the value of J3+(aq)/J(s)(1 mark)4.The flow diagram shows the extractions of lead and zinc metals. Study it and answer the questions that follow.Substance KCokeoresChamber MChamber NGas QSulphuric (IV) Chamber PMolten ZincMolten leada) i) Name the chief ores used in the extraction of;Zinc(? mark)Lead(? mark)ii) Identify substances K and Qiii) State the function of coke in chamber N(1 mark)iv) Write a chemical equation for the reaction between gas Q and calcium hydroxide solution(1 mark)v) What property makes it possible to separate the two metals(1 mark)vi) Explain why zinc is preferred for coating iron to copper(1 mark)Page | 13600Chemistry paper 1, 2&3 vii) State two effects that this process would have on the environment(2 marks)viii) Give one use of zinc(1 mark)b) The process of obtaining pure zinc is by electrolytic method. (i) Name the electrolyte used in the electrolytic method(1 mark)(ii) Describe an experiment carried out to determine the presence of zinc metal in a sample of soil using dilute Sulphuric (vi)acid and aqueous ammonia(2 marks)5.The flow chart below show the large scale manufacture of ammonia by haber process. Study it and answer the questions thatfollow.HydrogenGas RPurifier Unreacted gases Compressor 500 atm Condenser Chamber P Mixture of Liquidhot gasesCatalyticammoniachamber500?Ca) Identify gas R(1 mark)b) i) Name two sources of hydrogen gas used in the process(2 marks)ii) Explain the reason why the mixture of hydrogen gas and gas R are passed through the purifier(2 marks)iii) Name a suitable catalyst used in the catalystic chamber(1 mark)c) i) Identify chamber P(? mark)ii) Explain why mixture of hot gases is passed through chamber P(1 mark)iii) Write an equation for the main reaction in the catalytic chamber(1 mark)d) Explain using equations the following observationHot platinum wire glows on coming into contact with fumes of Ammonia(2 marks)e) State two industrial uses of ammonia(1 mark)6.a) Define the term molar heat of formation(1 mark)b) Use the following standard enthalpies of combustion to answer the questions that follow. ΔH?c (carbon) = -393kJmol-1 ΔH?c(H2g) = -286kJmol-1 ΔHc(C4H10) = -1290kJmol-1 (i) Write the equation for the formation of butane(1 mark)(ii) Draw an energy level diagram that links heat of formation of butane with its heat of combustion and the heats of combustionof carbon and hydrogen(3 marks)(iii) Calculate the standard heat of formation of butane(2 marks)c) Determine the heating value of butane(1 mark)Page | 13700Chemistry paper 1, 2&3 d) Use the bond energies below to calculate the enthalpy change for the formation of chloromethane from methane gas and chlorine gas BondBond energy in kJmol-1H-Cl431Cl-Cl242C-H413(3 marks)7.I. The solution in grams of sodium nitrate in 100g of water is given for various temperature in degree celciusTemperature01020304050608090100Solubility73808896104114124148162180a) Draw a graph of solubility of sodium nitrate against temperature(3 marks)b) From the graph determine the solubility of sodium nitrate at70?C(1 mark)c)100 grams of a saturated solution of sodium nitrate at was cooled from 80?C to 10?C. What mass will crystallize out(2 marks)IIStudy the flow chart below and answer the questions that follow.Solid PYellow powder + Brown gasDilute nitric (v) acid ColourlessExcessWhite precipitateAmmonia solution(i)Write the chemical formula of;a)Solid P(1 mark)b) The white precipitate(1 mark)IIIStarting with copper(II) carbonate, describe how a solid sample of copper (II) sulphate crystals would be prepared(3 marks) Page | 138Chemistry paper 1, 2&3 MOKASA JOINT EVALUATION EXAM 233/3 CHEMISTRY PRACTICAL MOKASA 2016 CONFIDENTIAL INSTRUCTIONS TO SCHOOLS A part from other laboratory apparatus and fittings each student is expected to have the following. ?A burette?A 25 ml pipette?3 volumetric flasks?Distilled water in a wash bottle?Solution R - 0.1M MCl?Stiring rod?A 250ml volumetric flask?A 250ml beaker?A label?About 2g solid Q?Methyl orange indicator supplied with a dropper?Solution C?Solution D?1 - 50ml measuring cylinder?1 - 10ml measuring cylinder?1 stop watch?About 1.0g solid K?About 1.0g solid Z?Litmus papersAccess to:1.Sodium hydroxide solution2.1M Lead (II) nitrate3.1M Barium nitrate4.Bunsen burner5.Acidified potassium manganate VII6.Sodium carbonateNB: Solution C - 0.1M Na2 S2 O3(aq) Solution D - 2.0M HCl(aq) Solid K - NH4Cl Solid Z - Maleic acid Page | 139Chemistry paper 1, 2&3 MOKASA JOINT EXAMINATION - 2016 Kenya Certificate of Secondary Education 233/3 CHEMISTRY Paper 3 PRACTICAL Time: 2 ? hours 1. You are provided with; ? Solid Q, 2.0g of impure sodium carbonate (contaminated with sodium chloride). ? Solution R, hydrochloric acid solution, containing 2.07g of the acid in 500 cm3 of solution. You are required to determine the percentage impurity in solid Q. Procedure: (i) Place all solid Q in a beaker and add 100cm3 of distilled water. Stir well a glass rod. (ii) Transfer the solution into a 250 cm3 volumetric flask and top it up to the mark with distilled water. Shake well and label as solution Q. (iii) Fill a burette with solution R. (iv) Pipette 25.0 cm3 of solution Q into a conical flask. Add three drops of methyl orange indicator. (v) Titrate solution Q against solution R from the burette. Record the results in the table below. (vi) Repeat the titration two more times and complete the table. Table I (a)IIIIIFinal burette reading (cm3) Initial burette reading (cm3) Volume of solution I used (cm3) (4marks) (a) Determine the average volume of solution R used.(1 mark)(b) Calculate the concentration of solution R in moles per litre.(2 marks)(H = 1.0, Cl = 35.5)(c) Calculate the number of moles of the acid in solution R that reacted.(1 mark)(d) Write an equation for the reaction that occurs.(1 mark)(e) Calculate the number of moles of sodium carbonate in 25 cm3 of solution Q that reacted.(1 mark)(f) Calculate the mass of sodium carbonate in 250 cm3 of solution Q.(2 marks)(C = 12.0, O = 16, Na = 23) (g) Find the percentage of mass of the impurity, sodium chloride, in solid Q.(2 marks)2. Your are required to investigate the effect of change in concentration on the reaction rate between sodium thiosulphate solution C and dilute hydrochloric acid solution D. When hydrochloric acid is added to sodium thiosulphate sulphur is deposited. ()()()()()( )The time taken for sulphur to reach a certain amount can be used to indicate the rate of the reaction. Solution C contains 0 .08 moles of sodium thiosulphate in one litre of solution. Procedure: (i) Measure 40 cm3 of solution C and pour it into a 100 cm3 glass beaker. (ii) Mark a cross (X) on a white paper. Place the beaker containing solution C over the cross on the paper. (iii) Measure 10 cm3 of solution D add it to the solution C in the beaker. Start the stopwatch immediately. Observe the cross on the white paper from the top of the beaker and record the time taken for it to be obscured (to disappear from view). (iv) Repeat the experiment using different volumes of solution C as indicated in the following table and in each case water is added to make a total of volume of 40 cm3. The same volume of hydrochloric acid is added in each case. Complete the table below.(5 marks)Volume of HCl usedVolume of Na2S2O3 used cm3Volume of water addedTime taken (s)(cm3)solution()10400103010102515102020101030Page | 140Chemistry paper 1, 2&3I.On the grid provided plot a graph of the reciprocal of time( )y-axis against volume of solution C used.(3 marks) II. From the graph determine the time taken for the cross to disappear if 35 cm3 of solution C was used.(1mark)III. Explain the shape of the graph in terms of rates of reaction.(1 mark)3.I.(a) You are provided with solid K. Carry out the tests below. Write your observations and inferences in the spaces provided. Place all of solid K in a boiling tube, add about 10cm3 of distilled water and shake until all the solid dissolves. Divide the solution into 4 portions. (i) To the first portion in a test-tube, add a few drops of sodium hydroxide until in excess. Retain the mixture for procedure (b). ObservationsInferences(1mark)(1mark)(i) Warm the mixture in (a) above and test any gases produced using red and blue litmus papers.ObservationsInferences(1 mark)(1 mark)(iii)To the third portion, add about equal volume of freshly lead (II) nitrate solution followed by a few drops of dilute nitric(V) acid.ObservationsInferences(1 mark)(1mark)(iv) To the fourth portion add Barium nitrate solution.ObservationsInferences(1mark)(1mark)II. You are provided with substance Z. Carry out the tests below. Write your observations and inferences in the spacesprovided.(a) Scoop a little of solid Z using a clean spatula and burn it in a Bunsen burner flame.ObservationsInferences( 1 mark)( 1 mark)Divide the remaining amount into two portions.(b) To the first portion, add water and shake.ObservationsInferences( 1 mark)( 1 mark)(c) To the second portion, add potassium manganate (VII) and warm.ObservationsInferences( 1 mark)( 1 mark)(d) To a little amount of Z, add sodium carbonate.ObservationsInferences( 1 mark)( 1 mark)Page | 141Chemistry paper 1, 2&3 M O K A S A J O I N T E X A M I N A T I O N Kenya Certificate to Secondary Education CHEMISTRY PAPER 1 TIME: 2 HOURS MARKING SCHEME 1.Explain the following:i)It is always advisable to scoop chemical substances using a clean spatula.(? mark)To prevent contamination of the chemicals. ii) Flammable substances should always be kept away from flames in the laboratory.(? mark)To prevent fire accidents.2.Name one reagent that can be used to distinguish between Al3+ and Zn2+ ions in solution and state what would be observed ifeach of the ions is treated with the reagent you have named.(3 marks)Ammonia solution Al3+ - A white precipitate would be formed which is insoluble in excess ammonia solution. Zn2+ - A white precipitate would be formed which is insoluble in excess ammonia solution. 3. i)Water is added to the equilibrium mixture.(1 ? marks)Increasing the concentration of water would shift the equilibrium to the left.ii) Hydrogen chloride is bubbled into the equilibrium mixture.(1 ? marks)HCl would react with the H2S thereby reducing its concentration. The equilibrium would shift to the right.4.Use the thermochemical equations below to answer the questions that follow.Calculate the enthalpy of formation of ethane.(1 ? marks)()()5.The acid must be concentrated and hot( )( )()()( )6. When 8.8g of hydrocarbon Z was burnt in excess air, 14.4g of water and 11.95 dm3 of carbon (IV) oxide were obtainedat s.t.p. Determine the empirical formula of Z.(3 marks)Mass of C in CO2Mass of C in CO214.4Mass of CO2 == 1.6gMass of C == 6.4ElementsCHMass in grams6.41.6R.A.M121No. of molesRatio of molesFormulaCH37.(a) Write the structural formula of the monomer of Perspex.(1 mark)CH3CH2CCOOCH3(b) Addition polymerization8.Zn(s)+ H2 SO4(aq)ZnSO4(aq) + H2(g)Zn(s)+ 2H2 SO4(l)ZnSO4(aq) + SO2(g) + 2H2O(l)9.(a) Identity solid X.Hydrated iron (III) oxideAccept rust(b) Write an ionic equation for the reaction between P and copper (II) sulphide solution.H2S(g)+ Cu2+(aq)→ CuS(s) + 2H+(aq)Page | 142Chemistry paper 1, 2&3 (c) State the observation made when gas P is bubbled through iron (III) chloride solution. The yellow iron (III) chloride solution turns green. 10.(a)X Alpha particlesY Beta particles(b)Gamma radiatons11.P - when used with hand water it does not form scum.12.You are given the following half equations:(i)Mg(s) + Zn2+(aq)→ Mg2+(aq) + Zn(s)(ii)E.m.f. = E0 reduced - E0 oxidised= -0.76 + 2.37= +1.61V(iii)Zn2+ ion13.(a)Aluminium chloride.(1 ? marks)(b)Sulphuric (IV) oxide.(1 ? marks)14.(a)Write the electron arrangement of:(1 mark)(i)ion of S -2.8(ii)atom of T-2.8.4(b)Explain why the melting point of T is higher than that of U.(2 marks)Atoms are covalently bonded together to form a giant atomic structure. Atoms of U are bonded covalentlyto form molecules. The molecules are then hold together by weak Van der waals to form a simplemolecule structure.plete the table below.(3 marks)MetalAluminiumLeadSodiumChief oreBauxiteGalenaRock saltChemical nameAl0O3.2H2OPbSNaClMethod of extractionElectrolysisreductionElectrolysis16.(a)Name substance X.(1 mark)Hydrogen (b)What is the purpose of the glass beads?(1 mark)They increase the surface area over which the gas dissolves in water. (c)Give one use of hydrochloric acid.(1 mark)? Treatment of water at the water works ? Sewage treatment ? Manufacture of dyes, drugs etc ? To clean metal surfaces to remove rust 17.No. of moles NH4NO3 =NH4NO3(s)→ N2O(s)+ 2H2O(l)1 mole:1 moleMoles of N2O= 0.4775If 1 mole occupies 22400cm3then0.4775→ xx= 0.4775 x 22400= 10696 cm3 or 10.696 dm318.(a)iron reacts with steam.(1 mark)3Fe(s) + 4H2O(g)→ Fe3O4(s) + 4H2(g)(b)Give one industrial use of the gas produced in the reactions in (i) and (ii) above.(1 mark)? Industrial manufacture of hydrochloric acid? Industrial manufacture of Ammonia? Used in weather balloons19.(a)2Mg(s) + O2(g)→2MgO(s)3Mg(s)+ N2(g)→ Mg3 N2(s)(b)FourPage | 143Chemistry paper 1, 2&3 20. a) At constant temperature, the volume of a fixed mass of gas is inversely proportional to pressure or V α, V=?b)√ R.M.M of SO2 = 64R.M.M of O2= 32=√Time for SO2 = 70.7 seconds21.The red litmus paper is bleached. This is because chlorine gas has bleaching property.22.(a)Kerosene floats on water therefore it continues to burn. Carbon (IV) oxide cuts off the supply of oxygen.(b)CO23.The molecules of chlorine are smaller compared to those of iodine; thus the strength of the intermolecules forcesof attraction in iodine are much stronger than in chlorine.24.A proton is positively charged whereas an electron is negatively charged.The mass of a proton is/atomic mass units whereas that of an electron isa.m.u25.Electron affinity26.Add water to a small sample of the fertilizer in a test tube and shake well. Filter to obtain a solution. To thesolution add some freshly prepared ion (II) sulphate solution and shake well. With a test tube in a slantingposition, add concentrated sulphuric (VI) acid to the mixture carefully along one side of the tube. A brown ringbetween two layers indicates the presence of nitrate ions.27.(a)Lead (II) nitrate(1 mark)2Pb(NO3)2 (s)→2PbO(s)+ 4NO2(s)+ O2(g)(b)Silver nitrate(1 mark)2Ag NO3(s)→2Ag(s)+2NO2(g)+ O2(g)28.An oxide that behaves as an acid or a base in chemical reactions.29.Heat the zinc carbonate solid in a test tube to obtain zinc oxide. To a certain volume of dilute nitric (V) acid thezinc oxide a little at a time while stirring till in excess. Filter the unreacted zinc oxise. To the filtrate add aqueous30.(a)Name Y, X and T(1 ? marks)YChlorine gasXHydrogen gasTButyl hydrogen sulphate(b)Give the name of the following organic compounds.(? mark)(i)Ethanoic acid(ii)Ethylpropanoat(iii)Sodium ethanoate31.Mass of saturated solution= 26.86 - 15.86= 11.0 g Mass of dry salt= 16.70 - 15.86= 0.84 g Mass of solvent (water)= 11.0 - 0.84= 10.16 g If 0.84g dissolve in 10.16 g of water then x g dissolve in 60 g of water Mass of saturated solution = 60 + 4.9606 = 64.9606 g Page | 144Chemistry paper 1, 2&3 MOKASA JOINT EXAMINATION - 2016 Kenya Certificate of Secondary Education CHEMISTRY Paper 3 PRACTICAL Time: 2 ? hours 1.You are provided with;Table I(a)IIIIIFinal burette reading (cm3)Initial burette reading (cm3)Volume of solution I used (cm3)(a)(b)(c)(d)(e)(f)((g)2.Determine the average volume of solution R used.(1 mark)Calculate the concentration of solution R in moles per litre.(2 marks)(H = 1.0, Cl = 35.5)MM of HCl2.07g500cm3= 1 + 35.5== 36.5= 4.14g/l= 0.1134MCalculate the number of moles of the acid in solution R that reacted.(1 mark)1000cm3 = 0.1134 molesAv.=Write an equation for the reaction that occurs.(1 mark)()()()()( )Calculate the number of moles of sodium carbonate in 25 cm3 of solution Q that reacted.(1 markMole ratio1 : 2Calculate the mass of sodium carbonate in 250 cm3 of solution Q.(2 marks)(C = 12.0, O = 16, Na = 23)Mass = moles x MM)()= 106() Volume of HClVolume of Na2S2O3 used cm3Volume of waterTime taken (s)used (cm3)solutionadded()10400103010102515102020101030I.On the grid provided plot a graph of the reciprocal of time( )y-axis against volume of solution C used. Page | 145Chemistry paper 1, 2&3 II.From the graph determine the time taken for the cross to disappear if 35 cm3 of solution C was used.Use the graph35cm3 = ?Time =III.Explain the shape of the graph in terms of rates of reaction.The graph is a straight line showing increase in the volume hence concentration of solution C increase inthe rate of reaction.3.I.(a)i)ObservationsInferencesNo white precipitate is formed 3= 1 mk2= ? mk (1 mark)1= 0 (1)(ii) ObservationsInferencesMoist litmus paper turns blue and moist blue litmus paper remains blue (1 mark)(1 mark)(iii)ObservationsInferencesWhite precipitate is formedInsoluble in aci(1 mark)(1mark)(iv)To the fourth portion ad Barium nitrate solution.ObservationsInferencesNo white precipitate formed (1 mark)(1mark)II. a) Scoop a little of solid Z using a clean spatula and burn it in a Bunsen burner flame.ObservationsInferencesBurns with a yellow sooty flame/smocky||C= C||( 1 mark)- CC-( 1 mark)b) To the first portion, add water and shake.ObservationsInferencesDissolve to form a colourless solutionR - OH( 1 mark)R - COOH( 1 mark)c) To the second portion, add potassium manganate (VII) and warm.ObservationsInferencesPurple potassium manganate (VII) is||decolourisedC = C( 1 mark)||C CR - OH( 1 mark)d) To a little amount of Z, add sodium carbonate.ObservationsInferencesEffervescence occurs ( 1 mark)R - COOH( 1 mark)Page | 14600Chemistry paper 1, 2&3 KUWED EXAMINATION COUNCIL 2016 233/1 CHEMISTRY PAPER 1 (THEORY) JULY/AUGUST 2016 TIME: 2 HOURS. 1. The figure below shows part of a Bunsen burner. Study it and answer the questions that follow. A BCD(a)Name labelled parts A, B, C and D.(2 marks)(b)State the function of the part labelled B.(1 mark)2.A mixture contains ammonium chloride, silver chloride and lead (II) chloride. Describe how each of the substance can beobtained from the mixture.(3 marks)3.(a) State the Graham?s law.(1 mark)(b)A volume of 80cm3 of nitrogen gas diffused through an oriffice in 40 seconds. How long will 170cm3 of carbon (IV) oxidetake to diffuse through the same oriffice? (N = 14, C = 12, O = 16)(2 marks)4.The diagram below was used to prepare gas X.Gas x Trough Water Potassium chlorate + Manganese (IV) Oxide Heat (a)Identify gas x.(1 mark)(b)Write an equation for the reaction that took place.(1 mark)(c)Identify the method of gas collection above.(1 mark)5.The table below represents elements P, Q, R and S. Study it answer the questions that follow. (The letters are not the actualsymbols of the elements.ElementAtomic numberAtomic radius (nm)Ionic radius (nm)P130.1210.061Q140.1010.043R170.0990.181S180.023(a)Explain why the atomic radius of element P is greater than that of element R.(1 mark)(b)Explain why the atomic radius of element R is less than its ionic radius.(1 mark)(c)Using dots (?) and crosses (X) show bonding in the compound formed between elements Q and R.(1 mark)6.The diagram below was used in the electrolysis of aqueous copper (II) sulphate using copper electrodes.Copper electrodes Copper (II) sulphatePage | 14700Chemistry paper 1, 2&3 (a) Label the electrodes above.(1 mark)(b) Give the observation made at the cathode.(1 mark)(c) Write the half-equation for the reaction at the anode.(1 mark)7.A 2.0g of limestone was allowed to react with 200cm3 of 0.2MHCl acid. The excess acid required 49.6cm3of 0.1M NaOHsolution. Calculate the percentage of calcium carbonate in the limestone. (Ca = 40, C = 12, O = 16)(3 marks)8.(a) Give the IUPAC name of the following compound.(3 marks)(i) CH3C (CH3)2CH3 O // (ii) CH3C-O-CH2CH2CH3 H H H H H |||||(iii) H-C-C-C-C-C-OH|||||H H H H H(b) Describe a chemical test that can be used to distinguish between compound (i) and (iii)(1 mark)9.(a) State any two differences between a chemical reaction and a nuclear reaction.Chemical reactionNuclear reaction(i)(ii)(b) State two uses of radioactivity in Agriculture.(1 mark)10.(a) What are acid-base indicators.(1 mark)(b) Substance A reacted with both an acid and a base as shown below.AcidABase(i) State the nature of A(1 mark)(ii) Name any two oxides of A(1mark)11.(a) Differentiate between endothermic and exothermic reaction.(1 mark)(b) Study the heating curve below and answer the questions that follow. Bpt(0C)DEB Mpt(0C)CA (i) Identify the process taking place between B and C(1 mark)(ii) Is the process you have named above endothermic or exothermic? Explain(1 mark)12. Steam was passed over heated iron wool as shown below.Iron wool Point XSteamHeat (i) What is the precaution taken before lighting the gas at point X.(1 mark)(ii) Write the chemical equations taking place.I. In the combustion tube(1 mark)II. At point XPage | 14800Chemistry paper 1, 2&3 13. The following table shows the effect of heat on three metal nitrates P, Q and R. Metal nitrateProduct on heatingPMetal oxide + Oxygen + Nitrogen (IV) OxideQMetal nitrite + OxygenRMetal + Oxygen + nitrogen (IV) Oxide(a) Arrange the metals P,Q and R in order of decreasing reactivity.(1 mark)(b) Name a metal that is likely to be(i) R(? mark)(ii) Q(? mark)14. Given the equation.H2(g) + I2(g)2HI(g) ? = -20kJ mol-1Explain what will happen to the yield of hydrogen iodide if:-(i) Temperature is increased(1 mark)(ii) Pressure is reduced(1 mark)15. Study the flow chart below and answer the questions that follow. NaOH(aq)FatBoilStep ISolution of cleaning agent and an alcoholStep IISolid cleaning agent (i) Name the type of cleaning agent prepared in the scheme above.(1mark)(ii) Name the chemical substance added in step II and state its function.(1 mark)(iii) Give one advantage of using the cleansing agent above.(1 mark)16. A compound of carbon hydrogen and oxygen contains 57.15% carbon, 4.76% hydrogen and rest oxygen. If its relativemolecular mass is 126, find its molecular formula. (C = 12, H = 1, O = 16)(3 mks)17. A student from Ikerege Secondary School poured accidentally concentrated sulphuric acid on his brown sugar.(i) State and explain the observation made.(1 mark)(ii) Write the chemical reaction that took place.(1 mark)18.(a) What are allotropes?(1 mark)(b) Below are allotropes of carbon.AB(i) Identify allotrope A and B(2 marks)(ii) With a reason, identify the allotrope that can be used in the making of pencil.(1 mark)19. The following diagram shows how chlorine gas can be prepared in the laboratory. Conc. HCl Manganese (IV) Oxide Heat (a) Complete the diagram to show how a dry sample of chlorine gas can be collected.(2 marks)Page | 14900Chemistry paper 1, 2&3 (b) Apart from manganese (IV) oxide, give the formula of any two compound that can be used in the preparation of chlorine. (1 mark) (c) Give one industrial use of chlorine gas(1 mark)20.(a) Define second ionisation energy(1 mark)(b) Explain why the second ionization energy is higher than the first ionization energy.(1 mark)21.(a) What is a saturated solution?(1 mark)(b) A saturated solution of a salt Y at 300C weighing 76g yielded 34g of solid when evaporated to dryness. What is the solubility of the salt at 300C.(2 marks)22. The flow chart below shows the extraction of lead metal. Study it and answer the questions that follow. Gas XChief oreRoastedStep ILead (II) OxideStep IICokeSubstance M +CO2(g) (a) Give the name of the chief ore.(1 mark)(b) Identify gas X(1 mark)(c) Write the chemical reaction taking place in step II.(1 mark)23. Study the energy level diagram below and use it to answer the questions that follow. Na+(s) + Cl-(g) ? H2 NaCl(s) ? H3 Na+(aq) + Cl-(aq) Reaction path (a) Identify the heat change ?H1 and ?H2(1 mark)(b) Given that the heat change for ?H1 is -1224kJmol and ?H2 is -1050kJmol-1. Calculate the heat change for the reaction?H3.(2 marks)24. The diagram below shows a chromatogram that was used to identify athletes M and N who had consumed illegal substancesA, B, C. Use it to answer the questions that follow.(i) Identify the athlete who had consumed the illegal substance.(1 mark)(ii) Which of the three drugs was less absorbed?(1 mark)Page | 15000Chemistry paper 1, 2&3 25. Study the flow chart below carefully.White precipitateStep II Excess NaOHColourless solution MStep Irless solution NExcess NH3 (aq) (a) Identify the cation in the colourless solution N.(1 mark)(b) Write ionic equations for the reactions in Step I.(1 mark)26. The sketch of the graph below shows a reaction between magnesium ribbon and dilute hydrochloric acid.0.1M HCl Time is seconds (a) On the graph indicate the curve for 0.05M HCl(1 mark)(b) Other than change in concentration, name two other factors that can affect the rate of reaction above.(1 mark)27.80cm3 of ethane reacted with 150cm3 of oxygen forming carbon (IV) oxide and water.Calculate:(i) The volume of carbon (IV) oxide formed(1 mark)(ii) The residual air.(1 mark)28. The set up below was used to prepare a hydrocarbon.Water Gas YWaterSolid XSand(a) Define a hydrocarbon.(1 mark)(b) Name solid X(1 mark)(c) Give a reason why sand is placed at the bottom of the flask.(1 mark)(d) Write a balanced equation for the reaction taking place in the flask.(1 mark)Page | 15100Chemistry paper 1, 2&3 KEWED EXAMINATION COUNCIL 2016 233/2 CHEMISTRY PAPER 2 (THEORY) JULY/AUGUST 2016 TIME: 2 HOURS. 1.Below is a grid which represents part of the periodic table. Use it to answer the questions that follow. The letters do notrepresent the actual symbols of the elements.AAJNOQSKL(a)Briefly explain why element A is placed in the two positions in the table.(1 mark)(b)What name is given to the group of elements to which L belongs?(1 mark)(c)What name is given to the element that occupy the shaded region?(1 mark)(d)1.3g of L reacts completely with 1.21dm3 of Q when heated at s.t.p (Molar gas volume = 22.4dm3). Using the actual symbols,write a balanced chemical equation for the reaction between L and Q.(2 marks)(e)How would the boiling points of element A and Q compare? Explain.(2 marks)(f)Give one use of element S(1 marks)(g)Identify the strongest reducing agent.(1mark)(h)Study the data in the table below and answer the questions that follow. (The letters do not represent actual symbol of theelement)ElementAtomic No.MP (0C)BP(0C)Ionic radiiC11988900.095D1265011100.065E1366024700.050F14141023600.041G1544.22800.034H161134450.184I17-101-350.181J18-189-186-(i)Using dots and crosses, draw, the structure of chloride of element D.(2 marks)(ii) Explain why there is an increase in boiling points from C to E.(1 mark)2.(a) Define allotropy(1 mark)(b) Graphite is an allotrope of carbon, which conducts electricity although carbon is a non-metal.Explain.(2 marks)(c) Carbon reacts with hot concentrated sulphuric (VI) acid.(i) Write an equation for the reaction that occurs.(1 mark)(ii) What property of carbon is shown in this reaction?(1 mark)(d) Sodium carbonate can be produced from trona, a double salt, whose formula is NaCO3.NaHCO3.2H2O. What is meant by a double salt?(1 mark)(e) Sulphur is extracted from underground deposits by the process shown below.ABC Ground level Rock containing sulphur (i) Water at 1700C is pumped down the outer pipe. Explain how it is possible to obtain water with temperature of 1700C. (1 mark) (ii) Name the substances passed through; (a) Pipe A(1 mark)(b) Pipe B(1 mark)(f) When excess chlorine gas is bubbled through dilute sodium hydroxide, the resulting solution bleaches flower petals.(i) Write an equation for the reaction between chlorine and dilute sodium hydroxide solution.(1 mark)(ii) Explain how the resulting solution bleaches flower petals.(2 marks)3.(a) In which homologous series do the following compound belong.(i) CH3CCH(1 mark)Page | 15200Chemistry paper 1, 2&3(ii) CH3CH2CH2OH(iii) Give the IUPAC name of the compound in part (ii) above. (b) Study the flow chart below and answer the questions that follow;Potassium metalSubstance ASteamHigh pressureProcess 2(1 mark)(1 mark)Substance P + Hydrogen gas2 moles of Br2(l)(c)4.(a)(b)(c)C2H5OHCH2=CH2HC?CHEConc. H2SO4H2OCatalyst H2(g)HCl(g)BSubstance WCompound DKMnO(aq)H+(aq)PolymerizationCFC3H7OH/Few drops of Conc. H2SO4 and warmCompound M(i) Identify substance; A,W,D and P(ii) Write an equation for the formation of substance E.(1 mark)(iii) State the condition and reagent that are required in process 2.Condition_________________________________________(1 mark)Reagent __________________________________________(1 mark)(iv) Draw the structural formula of compound F showing two repeat units of compound F.(1 mark)The organic compound E was found to contain 12.5% carbon, 2.4%b hydrogen and the remaining bromine. If its relative molecular formula was found to be 188, determine its molecular formula. (C = 12, H = 1, Br = 80) (3 marks)Hydrazine gas whose structural formula shown below burns in oxygen to form nitrogen gas and steam.HHNNHHWrite an equation for the reaction.(1 mark)Using the bond energies given below, calculate the enthalpy change for the reaction in (a) above. Bond Bond energy (kJmol-1)N?N944N-N163N-H388O=O496H-O463(i) What is meant by the term “enthalpy of formation”?(1 mark)(ii) The enthalpies of combustion of carbon, methane and hydrogen are indicated below.C(s) + O2(g)? CO2(g)?H = -393kJmol-1H2(g) + ? O2 ? H2O? H = -286kJmol-1CH4(g) + 2O2(g) ? CO2(g) + 2H2O(l) ? H = -890kJmol-1I.Draw an energy cycle diagram that links the enthalpy of formation of methane to combustion of carbon, hydrogen andmethane.(1 mark)II. Determine the enthalpy of formation of methane.(2 marks) (d)(i) Work out the oxidation number of Mn in MnO(1 mark)Page | 15300Chemistry paper 1, 2&3 (ii) The following table gives the standard electrode potentials for some half reactions. Half reactionE? voltsZn2+(aq) + 2e- ? Zn(s)-0.76Fe2+(aq) + 2e- ? Fe(s)-0.44I2(aq) + 2e- ? 2I-(aq)+0.54Fe3+(aq) + 2e- ? Fe2+(aq)+0.77With reference to the above table, which is the strongest oxidizing agent?(1 mark)(iii) Study the cell diagram below and answer the questions that follow.Fe(s)/ Fe2+(aq), 1M//Fe3+(aq) 1M, Fe2+(aq) 1M/PtI.In which half cell would reduction take place.(1 mark)II. Calculate E? values for the cell represented in d (iii) above.(2 marks)5.The set-up below is an incomplete diagram that was used to prepare and collect nitrogen gas, in the laboratory.Mixture of sodium nitrite andammonium chlorideHeat(a) Complete the diagram above to show how nitrogen gas is collected.(2 marks)(b) Using an equation, describe how nitrogen gas is formed in the flask.(2 marks)(c) Nitrogen is inert. State one use of the gas based on this property.(1 mark)(d) The equation below shows a dynamic equilibrium between nitrogen gas and hydrogen gas.N2(g) + 3H2(g)2NH3(g)?H = -ve(i) How would the yield of NH3(g) be affected if the pressure is decreased? Explain.(2 marks)(ii) How would the use of a catalyst affect the yield of ammonia?(2 marks)(iii) Name the type of reaction shown in the equation above.(1 mark)6.(I) Study the diagram below and answer the question that follow. The diagram shows the method of separating componentsof mixture.Z FractionatingRcolumn X Q Mixture P Heat (a) Name apparatus X.(1 mark)(b) State the function of the fractionating column?(1 mark)(c) Name the above method of separating mixtures.(1 mark)(d) Using letters R and Q, identify the water inlet and water outlet.(2 marks)Page | 15400Chemistry paper 1, 2&3 II. In an experiment to determine the solubility of two salt M and N at different temperatures, as the student recorded his observation as shown below. Temperature (0C)0102030405060708090Solubility of M in g/100g of H2O14172025283340475564Solubility of N in g/100g of H2O25273032353740424548(a) Define the term solubility.(1 mark)(b) On the same axes, plot the solubility of M and N.(4 marks)(c) Determine;(i) the solubility of N at 650C.(1 mark)(ii) the temperature at which the two salts are equally soluble in water.(1 mark)(d) If 60g of M is dissolved in 100g of water and heated to 900C, calculate the amount of salt that crystallized out if it is collectedto 200C.(1 mark)7.(a) A radioactive substance emits three different particles. Give the symbol of the particle with the highest mass.(b)(i) Find the values of Z1 and Z2 in the nuclear equation below.? (c) The graph below represents a radioactive decay series for isotope K. Study it and answer the questions that follow. K 1401016LQMP81828384Atomic number(i) Write an equation for the reaction that occurs when isotope L changes to isotope Q. (ii) Name the type of radiation emitted when isotope K changes to isotope L. (iii) Identify a pair of isotopes of an element in the decay series.(d) (i) Name one copper ore.(ii) The flow chart below represents the extraction of copper.SilicaGas KCopperRoastingCu2SSmeltingCu2S(2 marks)(1 mark)(1 mark)(1 mark)Gas PCokeChamber NpyritesfurnaceI.Name gas K.FeORoastingfurnacefurnaceSlag MCu(l)Cu2O(s)Liquid copper(1 mark) II. Write an equation for the reaction that takes place in the first roasting furnace.(1 mark)III. Write the formula of cation present in the slag M.(1 mark)IV. Identify gas P.(1 mark)Page | 155Chemistry paper 1, 2&3 KUWED EXAMINATION COUNCIL 2016 233/3 CHEMISTRY PAPER 3 PRACTICAL JULY/AUGUST 2016 TIME: 2 HOURS 1. You are provided with:-? Solution R containing 5.3g per litre of anhydrous sodium carbonate. ? Solution L, hydrochloric acid. ? Methyl orange indicator ? Phenolphthalein indicator. You are required to standardize the hydrochloric acid. Procedure I Fill the burette with solution L. Pipette 25.0cm3 of solution R into a conical flask. Add three drops of phenolphthalein indicator and titrate with solution L. DO NOT pour out the contents of the conical flask. Repeat the procedure two more times to complete table 1 below, each time keeping the contents of the conical flask for procedure II. Table 1 (Using phenolphthalein indicator)(4 marks)123Final burette reading (cm3)Initial burette reading (cm3)Titre t1 (cm3)(a) Determine the average titre t1 (cm3)(1 mark)PROCEDURE IIAdd three drops of methyl orange indicator to the contents of the conical flasks and continue titrating with solution L. Recordthe readings in table II below. Repeat the procedure to complete the table below.Table II (Using methyl orange indicator)(4 marks)123Final burette reading (cm3)Initial burette reading (cm3)Titre t2 (cm3)(b) Determine the average titre t2 (cm3)(1 mark)(c) Calculate the total volume of solution L used(1mark)Total volume = t1 + t2(d) Calculate the concentration of solution R in moles per litre(1 mark)(Na = 23, C = 12, O = 16)(e) Calculate the moles of sodium carbonate in 25cm3 of solution.(1 mark)(f) Calculate the number of moles of hydrochloric acid in the total volume used.(1 mark)(g) Calculate the molarity of hydrochloric acid.(1 mark)2.You are provided with:-? Magnesium ribbon labelled solid T. ??2M hydrochloric acid labelled solution Q. ? Stopwatch You are required to determine the rate of reaction between magnesium and hydrochloric acid at different concentrations. Procedure i. Place five test tubes on a test tube rack and label them 1, 2, 3, 4 and 5. Using 10cm3 measuring cylinder, measure out the volumes of 2M hydrochloric acid, solution Q as shown in the table below, and pour them into corresponding test tubes. Wash the measuring cylinder and use it to measure the volumes of water as indicated in the table below and pour into the corresponding test tubes. ii. Cut out five pieces each of exactly 1cm length of magnesium ribbon, solid T. iii. Transfer all of the solution in test tube 1 into a clean 100cm3 empty clean beaker, place one piece of magnesium into the beaker and start a stopwatch immediately. Swirl the beaker continuously ensuring that magnesium is always inside the solution. Record in the table the time taken for the magnesium ribbon to disappear. Wash the beaker each time. iv. Repeat procedure III for each of the solutions in test tubes 2,3,4 and 5 and complete the table below.(5 marks)(a) ATest tube number12345Volume of solution Q (cm3)108642Volume of water (cm3)02468Time taken (seconds)Rate of reaction =()Page | 156Chemistry paper 1, 2&3 (b) On the graph below, plot the rate of reaction(y - axis) against the volume of solution Q(3marks)(c) Use your graph to determine the time that would be taken for 1cm length of magnesium ribbon to disappear if the volumeof the acid, solution Q used was 7.5cm3.(1 mark)(d) In terms of rate of reaction, explain the shape of your graph.(1 mark)3.(a) You are provided with solid M. Carry out the tests below on solid M and record your observations and inferences in thespaces provided.(i) Observe the appearances of solid MObservationsInferences( ? mark)( ? mark)(b) Put all the solid M into a boiling tube then add 8cm3 of distilled water and shake well. Divide the solution into four portions. (i) To the first portion, add 1cm3 of hydrogen peroxide and shake well. To the resulting mixture, add aqueous sodium hydroxide dropwise until in excess. ObservationsInferences(1 mark)( 1 mark)(ii) To the second portion, add 3 drops of aqueous ammonia until in excess.ObservationsInferences(1 mark)( 1 mark)(iii) To the third portion, add four drops of solution Q, (2M hydrochloric acid)ObservationsInferences(1 mark)( 1 mark)(iv) To the fourth portion, add 3 drops of aqueous lead (II) nitrate and warm.ObservationsInferences(1 mark)( 1 mark)(c) You are provided with liquid F. Carry out the following tests and record your observation andinferences in the spaces provided.(i) Place five drops of liquid F on a clean and dry watch glass and ignite it.ObservationsInferences(1 mark)( 1 mark)(ii) Place about 2cm3 of liquid F in a clean dry test - tube, add all the sodium hydrogen carbonateprovided.ObservationsInferences(1 mark)( 1 mark)(iii) Place about 2cm3 of liquid F in a test tube, add about 1cm3 of acidified potassium dichromate (VI) and warm the mixture.ObservationsInferences(1 mark)( 1 mark)Page | 15700Chemistry paper 1, 2&3 KUWED EXAMINATION COUNCIL 2016 Kenya certificate of secondary education (k.c.s.e.) 233/1 CHEMISTRY PAPER 1 MARKING SCHEME 1.(a) A - ChimneyB - Cotton C - Air hole D - Rubber tube/gas inlet (b) Used to regulate the amount of air entering the chimney. 2. (i) Heat the mixture to sublime ammonium chloride and collect it on cooler parts. (ii) Add hot water to the mixture to dissolve lead (II) chloride. (iii) Filter while hot to obtain silver chloride as a filtrate. (iv) Dry the residue in between filter papers. (v) Allow the filtrate to cool forming lead (II) chloride crystals. (vi) Decant or filter to obtain lead (II) chloride crystals. 3.(a) The rate of diffusion of a gas is inversely proportional to the square root of its density at the same conditions oftemperature and pressure.(b)= √√()√()√= √ √ √ 2x = √ ?x = 106.6 seconds 4.(a) Oxygen gas(b)2KClO3(s) ? 2KCl(s) + 3O2(g)(c) Over water method5.(a) R has greater +ve nuclear charge compared to element P.(b) R forms its ions by gaining electrons which brings about repulsion leading to increased size of the ion.(c)6.(a)AnodeCathode(b) The size of the cathode incre ses.Page | 158Chemistry paper 1, 2&3(c) Cu(s)? Cu2+ + 2e-7.HCl + NaOH ? NaCl + H2OMoles of NaOH=== 0.0496 molesMoles of HCl therefore were 0.00496Original no. y moles of HCl =Moles of acid that reacted with carbonate= 0.04 - 00496= 0.0350 molesMoles of carbonate (1 : 2)2 ? 0.03501 ?Mass of carbonate= Moles x RFM= 0.0175 x 100= 1.75g% =8.(a)(i)2,2 - dimethypropane(ii) Propylethanoate(iii) Pentane - 1 - ol(b) Use either a metal/acidified KMnO4 or K2Cro7 9. (a)(1) Takes place on the surface or involves electrons (2) Releases much less energy.(3) No effect on environmental factors(b) - Absorption of phosphate fertilizers- Photosynthesis and related processTakes place within nucleus and involves protons & neutronsReleases large amount of energy.Affects environmental factors 10.(a) These are substances which give definite colour acidic solution and a different definite colour in a basic solution.(b)(i) It is amphoteric in nature.(ii) Aluminium oxides, zinc oxides and lead (II) oxide,11.(a) Endothermic is a reaction that involves the gaining of energy from environment while exothermic are reactions that loseenergy to the environment.(b) i) Meltingii) Endothermic; because it involves bond making12.(i) Expel all the air from the combustion to avoid explosion.(ii) I.4H2O(g) + 3Fe(s) ? FeO4(s) + 2H2(g)II. H2 + 02 ? H2O(l)13.(a) Q,P,R(b)(i) R ? Silver/Mercury(ii) Q ? Sodium/Potassium14.(i) Increase in pressure favours a backward decrease.(ii) No yield on the yield; the number of moles remain the same.15.(i) Soapy detergent(ii) Calcium chloride; to precipitate the soap out.(iii) - It is cheap- BiodegradablePage | 15900Chemistry paper 1, 2&3 16. aCH0% Comp57.154.7638.09R.A.M12116Moles ratio2.0042.001Empirical fC2H2On == 3Molecular formula= (C2H2O)3= C6H6O317.(i) The brown sugar crystals was charred in a black mass; since conc. H2SO4 will remove the water molecules from sugarcrystals.Conc(ii) C12H22O11H2SO412C + 11H2O18.(a) These are substances that exist in different forms but same physical state.(b)(i) A - GraphiteB - Diamond (ii) A; It is slippery in nature. 19.(a)Moist blue litmus paper WaterConc. H2SO4(b) PbO2, KMnO4(c) Manufacture of hydrochloric acid20.(a)2nd ionization energy is the amount of energy required to remove the 2nd electron from the outermost energy level of anatom.(b) When the first electron is removed the remaining electrons are strongly attracted by the nuclear centres. 21. (a) A saturated solution is a solution in which no more solute can dissolve at a given temperature. (b) Mass of water 76 - 32 = 44 34g ? 44g of water ??100g of water77.27g/100g of water22.(a) Galena(b) Sulphuric (IV) oxide gas(c)2PbO(s)+ C(s) ? 2Pb + CO2(g)23.(a)? H1 - Enthalpy of lattice?H2 - Enthalpy of hydration(b)?H3 = ?H1 + ?H2= 1224+ - 1050= + 174KJmol-124.(a) Athlete M(b) A25.(a) Zn2+(b) Zn(OH)2 + 4NH3(Aq)? [(]2+ + 2OHPage | 16000Chemistry paper 1, 2&3 26.(a)0.1M HCl 0.05M HCl Time in seconds(b)- Temperature- Size of particles/Surface area27.(i) CH4 + 2O2? CO2 + 2H2OIV2V1V2V80cm3150cm375cm3 150cm3Volume of carbon (IV) oxide = 75 x 1 = 75cm3 (ii) Volume of water = 2 x 75 = 150cm3 Residual air= 5cm3 + 75cm3 + 150cm3= 230cm328.(a) Hydrocarbon is substance that contains hydrogen and carbon only.(b) Calcium carbide(c) Absorb excess heat and prevent bumping(d) CaC2(s) + 2H2O(l) ? C2H2(g) + Ca(OH)2(aq)Page | 161Chemistry paper 1, 2&3 KUWED EXAMINATION COUNCIL 2016 kenya certificate of secondary education (k.c.s.e.) 233/3 CHEMISTRY PAPER 3 MARKING SCHEME 1.Table 1123Final burette reading (cm3)10.020.030.0Initial burette reading (cm3)0.010.020.0Volume of titre t1 (cm3)10.010.010.0(a) t1 == 10.0cm3(i) Complete table with only two titrations1 mkIncomplete table with only two titrations? mkIncomplete with only 1 titration0 mkPenalties Penalise to a maximum of ? mk ? Wrong arithmetic ? Inverted table ? Burette readings beyond 50cm3 unless explained ? Unrealistic titre values i.e. values less than 1cm3 or beyond 100cm3 (ii) Decimals1mk? Tied to 1st and 2nd rows only. Accept 1 or 2 decimal places used consistently. ? If two decimal places are used, then the 2nd digit should be ?0? or ?5? ? Accept inconsistencies in use of zeroes. (iii) Accuracy1mkCompare any of the candidates titre values with the school value tick ( ?) this value and if within ? 0.1cm3 of school value.1 mk?b 0.2 of school value? mkIf outside ? 0.2cm30 mk(iv) Principles of averaging1 mk?3 consistent values averaged1 mk?3 titrations are done but are consistent and averaged1 mk?3 titrations done, are consistent but only 2 are averaged1 mk(v) Final answer? mkCompare the candidates average titre with the school value and award accordingly.Table II - Mark as table I123Final burette reading (cm3)8.016.024.0Initial burette reading (cm3)0.08.016.0Volume of titre t2 (cm3)8.08.08.0(b) Average t2 =(c) Total volume of solution L used = 10.0 + 8.0 ? mk = 18.0cm3 ? mk1mkOR Ans table 1 + Ans Table 2(d)? mk1 mk(e)= ? mk = 0.00125 moles ? mk1 mkOR= Correct ans(f)2 x 0.00125 ? mk = 0.0025 moles ? mk1mkOR e x 2 = Correct ans(g)= ? mk = Correct ans ? mk1 mk2.(a)Test tube number12345Volume of solution Q (cm3)108642Volume of water (cm3)02468Time taken (seconds)10204080125Rate of reaction()0.10.050.0250.01250.008Award marks as follows:-(i)Complete table3 mks?Award marks for time in seconds between 5 seconds to 360 seconds.Page | 16200Chemistry paper 1, 2&3 ?8 - 10 readings - 3 mks?5 - 7 readings - 2 mks?4 readings - 2 mks?4 readings - 1mk? Less than 4 readings - 0 mk(ii) Use of decimals1 mk? Accept whole numbers for time in seconds or if one dp is used, the last digit should be ?0? and award(? mk)? Accept atleast 3 dpl forunless the values are cancelling out exactly to less than 3 dpl and award(? mk). Otherwise. Ineither case, penalize fully.(iii) Accuracy1 mkCompare the first reading of the test tube 1 to school value. If within ? 2 sec, award 1 mk. Otherwise award 0 mk. (iv) Trend ? Tied to time in seconds. Award 1 mk for increasing trend. Otherwise award 0 mk. (b) Award marks for the graph as follows (i) Axes labelling? mkAward ? mk if both axes are correctly labelled with correctly labelled with correct units. Ignore if units are not included.(ii) Scale? mkAward ? mk if the scale is uniform on both axes and the plots covering atleast half of the graph.(iii) Plots1 mk? 4 - 5 plots1 mk? 3 plots? mk? Less than 3 plots0 mks(iv) Line1 mk? A straight line graph passing through the origin. ? Accept line of best fit, otherwise penalize fully. (c) Accept the candidates value if it?s from a correctly plotted graph. Otherwise penalize fully. ? Stating ? ? Conversion 1 mk ? Correct answer ? (d) A straight line graph, 1mk Rate if reaction increases as concentration increases 1mk or vice versa. 3.(a) (i)ObservationsInferencesGreen crystals ? mkColoured ions presentORCu2+/Fe2+/Fe3+ ions presentPage | 163Chemistry paper 1, 2&3 (b) (i)Observations? Yellow/Brown solution formed on addition of H2O2 ? Brown ppt insoluble in excess NaOH(ii)ObservationsDirty green ppt ? insoluble in excess ? mk(iii)ObservationsNo bubbles/Effervescence/fizzing 1mk(iv)ObservationsWhite ppt formed ? mk(c) (i)ObservationsBlue flame 1mk(ii)Observations? No effervescence/bubbles Fizzing sound 1 mk Rej? Fizzing on it own? Hissing soundInferences? Fe2+ oxidized to Fe3+ OR Fe3+ formed ? 1 mk Accept? Fe3+ present in solid M for ? mk ? Fe3+ present in the mixture for ? mkInferencesFe2+ ions 1 mkInferencesSOabsent 1 mkInferencesSOabsent ? mkCl-, SOInferences? Saturated organic compound 1 MKOR ? Organic compound with low C:H ratio OR|||??- C - C - /- C - present|||Accept absence of unsaturated organic compound for ( ? mk)? Ignore ROH if mentionedInferences? H+/R-COOH/-COOH absent 1mk Accept liquid acidic for ? mkRejectH2O+ ions absent (iii)ObservationsInferences? Potassium dichromate(VI) changes from orangeto? R-OH present 1mkgreen. 1mk ORReject? Solution changes from orange to green? OHReject? TreatSolution turns green||?- C = C - or - C= C - being present as||contradictory Page | 164 ................
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