AP CHEMISTRY – MINIMAL REVIEW



STOICHIOMETRYConvert 3.01 x 1023 atoms of rubidium to moles (0.500 mol Rb)The bond energy for HF is 568 KJ/mol. How much energy in Joules is required to break a single HF bond? (9.44 x 10-19 J)How many moles are present in 50.0 g of calcium chlorate? (0.242 mol)How many formula units are present in 0.272 g of nickel(II) nitrate? (8.96 x 1020)The density of liquid water is 0.997 g/mL at 25°C. How many moles of water are in 250.0 mL of water? (13.8 mol H2O)Determine the molarity of a solution prepared by dissolving 141.6 g of citric acid, C3H5O(COOH)3 , in water and then diluting the resulting solution to 3500.0 mL. (0.2106 M)What mass of glucose, C6H12O6, would be required to prepare 5.000 x 103 L of a 0.215 M solution? (1.94 x 105 g)Determine the mole fraction of a solution of 560 g of acetone, CH3COCH3, in 620 g of water. (0.219)What volume of water would be added to 16.5 mL of a 0.0813 M solution of sodium borate in order to get a 0.0200 M solution? (50.6 mL H2O)A chemist wants to prepare a stock solution of H2SO4 so that samples of 20.00 mL will produce a solution with a concentration of 0.50 M when added to 100.0 mL of water. What should the molarity of the stock solution be? (3.0 M)If the chemist wants to prepare 5.00 L of the stock solution from concentrated H2SO4 , which is 18.0 M, what volume of concentrated acid should be used? (0.83 L)The density of 18.0 M H2SO4 is 1.84 g/mL. What mass of concentrated H2SO4 should be used to make the stock solution in (b)? (1.5 x 103 g)Maleic acid, which is used to manufacture artificial resin, has the empirical formula CHO. Its molar mass is 116.1 g/mol. What is its molecular formula? (C4H4O4)Hydrated salts are very common. If you heat 2.105 g of CoCl2xH2O, and find that 1.149 g of CoCl2 remains, what is the value of x? (6)Ammonia gas can be prepared by the following reaction: CaO(s)+2NH4Cl(s) 2NH3(g)+ H2O(g)+CaCl2(s). If you mix 112 g of CaO and 224 g of NH4Cl, what is the theoretical yield of NH3? (68.1 g). What mass of excess is remaining? (10.3 g)Disulfur dichloride can be made by allowing chlorine gas to react with molten sulfur: S8(l) + 4Cl2(g) 4S2Cl2(g) If you begin with 12.0 g of S8 and 13.03 g Cl2 and you isolate only 15.2 g of S2Cl2, what is the percentage yield of S2Cl2? (60.1%)Styrene, the building block of polystyrene, is a hydrocarbon, a compound consisting only of C and H. If you burn 0.438 g of the compound, and find that it produces 1.481 g of CO2 and 0.303 g of H2O, determine the empirical formula of the compound. (CH)Aluminum bromide is a valuable laboratory chemical. If you use 25.0 mL of liquid bromine (D = 3.1023 g/mL) and excess aluminum metal, what is the maximum theoretical yield of Al2Br6? (86.3 g)In the photographic process silver bromide is dissolved by adding sodium thiosulfate, as shown in the balanced equation below. If you want to dissolve 0.250 g of AgBr(molar mass = 187.8 g/mol), how many mL of 0.0138 M Na2S2O3 should you add? (193 mL)AgBr(s)+2Na2S2O3(aq) Na3Ag(S2O3)2(aq)+NaBr(aq)A soft drink contains an unknown amount of citric acid, C6H8O7. If 100. mL of the soft drink required 33.51 mL of 0.0102 M NaOH to neutralize completely the citric acid, how many grams of citric acid (MM = 192.13 g/mol) does the soft drink contain per 100 mL? The reaction of citric acid with NaOH is(all aq) shown below. (0.0219 g)C6H8O7 + 3NaOH Na3C6H5O7 + 3H2O(l)NutraSweet is 57.14% C, 6.16% H, 9.52% N, and 27.18% O.? Calculate the empirical formula of NutraSweet and find the molecular formula.? (The molar mass of NutraSweet is 294.30 g/mol). (C14H18N2O5)Sodium thiosulfate, Na2S2O3, is used as a “fixer” in black and white photography. Assume you have a bottle of sodium thiosulfate and want to determine its purity. You can titrate the thiosulfate ion with I2 according to the equation below. If you use 40.21 mL of 0.246 M I2 in the titration, what is the weight percent of Na2S2O3 (MM = 158.12 g/mol) in a 3.232-g sample of impure Na2S2O3? (96.7 %) 2S2O32-?+ I2? S4O62-?+ 2I-Menthol, the substance we can smell in mentholated cough drops, is composed of C, H, and O. A 0.1005 g sample of menthol is combusted, producing 0.2829 g of CO2?and 0.1159 g of H2O. What is the empirical formula for menthol? (C10H20O)You are given a sample of a copper-containing alloy and asked to determine the mass percent of copper. After dissolving the metal in acid, you add an excess of KI, and the Cu2+ and I- ions undergo the reaction:2Cu2+ + 5I─ 2CuI + I3─The liberated I3- is titrated with sodium thiosulfate according to the equation:I3─ + 2S2O32─ S4O62- + 3I─If 26.32 mL of 0.101 M Na2S2O3 is required for titration to the equivalence point, what is the mass percent of Cu in 0.251 g of the alloy? (67.2%)ATOMConceptual StructureExplain all of the variables in Coulomb’s law as it applies to the atom.Differentiate among energy levels, sublevels, and orbitals. Include what each communicates about region is space where an electron is most likely to be found.Define AufBau principle, Hund’s Rule, and Pauli Exclusion principle. Explain each based upon maximizing attractive forces and minimizing repulsive forces in an atom.Write the complete electron configurations for the following atoms.RutheniumRadiumWrite the complete electron configurations for the following ions.Bismuth +3 ionIron +2 ionTellurium -2 ionWrite the noble gas configurations for the following atoms.NickelTungstenIdentify the element from the following photoelectron spectra. Indicate the sublevel and number of electrons represented in each peak of the spectra. Justify the difference in energy values for the same sublevels in each based upon atomic structure. PES can be used to identify elements in a mixture. What elements are present in the mixture below? PotassiumSiliconChlorineMixtureConceptual Periodic TrendsINTRO: You need to IDENTIFY and JUSTIFY the trends. You cannot use one trend (like electronegativity) to justify another trend (such as ionization energy). You answer must include a comparison of attractive forces (proton-electron) and repulsive forces (electron-electron). Distance from the nucleus, energy levels, conversion of energy levels, and shielding are critical components of a justification. STUDY MY SUMMARY CHART CAREFULLY!Which of the following groups of elements is arranged correctly in order of increasing first ionization energy?Mg < C < N < FN < Mg < C < FMg < N < C < FF < C < Mg < NWhich of the following groups of elements is arranged correctly in order of decreasing atomic radius?Mg < S < Al < ClAl < Mg < S < ClMg < Al < S < ClCl < S < Mg < AlWhich of the following elements would have the greatest difference between the first and the second ionization energy?LiB. CC. FD. NWhich of the following groups of isoelectronic species show the elements arranged correctly in order of increasing size?Na+ < O2- < F-F- < Na+ < O2-Na+ < F- < O2-F- < O2- < Na+An element having which of the following electronic configurations would have the greatest ionization energy?[He]2s22p3[He] 2s22p5[Ne]3s23p3[Ne]3s23p5Periodic trends:Which should be larger, the oxide ion, O2-, or the oxygen atom? Which should have the largest difference between the 1st and 2nd ionization energy? O, S, or Se Which of the following concerning second IE's is true? That of Al is higher than that of Mg because Mg wants to lose the second electron, so it is easier to take the second electron away. That of Al is higher than that of Mg because the electrons are taken from the same energy level, but the Al atom has one more proton. That of Al is lower than that of Mg because Mg wants to lose the second electron, thus the energy change is greater. That of Al is lower than that of Mg because the second electron taken from Al is in a p orbital, thus it is easier to take. The second ionization energies are equal for Al and Mg.Ionization Energies for element X (kJ mol?1) First Second Third Fourth Five 108623524619622137820The ionization energies for element X are listed in the table above. On the basis of the data, element X is most likely to be LiB. BeC. BD. CE. P Suppose that a stable element with atomic number 119, symbol Q, has been discovered.Write the ground-state electron configuration for Q, showing only the valence-shell electrons.Would Q be a metal or a nonmetal?On the basis of periodic trends, would Q have the largest atomic radius in its group or would it have the smallest? Explain in terms of electronic structure.What would be the most likely charge of the Q ion in stable ionic compounds?The correct ranking of alkali metals from most reactive to least reactive is:Be-Mg-Co-Sr-BaD. I-Br-Cl-FCs-Rb-K-Na-LiE. Li-Na-K-Rb-CsF-Cl-Br-I12MathematicalCalculate the average atomic mass of chromium given the following isotopes with abundance.Chromium-50Chromium-52Chromium-53Chromium-54Actual mass49.94504651.94051952.94065153.938882Abundance4.3583.799.502.36The mass spectrum below shows the relative % abundance for the isotopes of zinc. Redraw the spectrum so that the true % abundance is on the y-axis. WATCH Y-AXIS CAREFULLY ! I AM NOT SURE WHETHER AP WILL USE RELATIVE % OR ACTUAL %.Calculate the average atomic mass of zinc.Perform the following calculations regarding electromagnetic radiation.Convert 4.398 x 10-19 J to frequency.Convert 893 nm to energyThe energy of a photon is 8.22 x 10-18 J. What is the energy in KJ/mol?I am not AP will make you do these calculations, but performing them helps reinforce differences in atomic structure. Calculate the change in energy when an electron in hydrogen relaxes from n=3 to n=1.Calculate the change in energy when an electron in Li2+ relaxes from n=3 to n=1.Explain this difference in terms of atomic structure, potential energy, and coulomb’s law.BONDING Explain all of the variables in Coulomb’s law as it applies to bonding.IonicCovalentMetallic Differentiate among non-polar covalent, polar covalent, and ionic BONDS.What is/are the difference(s) between network covalent and molecular covalent bonding/compounds?Define each of the terms in the acronym VSEPR. How is the model used to predict the structure of molecular covalent substances?Predict whether the following pairs of atoms are more likely to form an ionic, metallic or covalent bond using only a periodic table. Justify your answer in each case.Al & GaZn & PP & BrRank the polarity of the following bonds using only a periodic table. Justify your answer. P — N, P—S, P—Br, P—ODefine formal charge. Calculate the formal charge of each element in the molecule below. How is formal charge linked to the selection of a possible structure of a molecule?Complete (and memorize!) the following summary chart for molecular covalent substancesBonding atoms (or group of atoms) on a defined central atomNon-bonded pairs of electrons on a defined central atom“ABX”Molecular structureBond angle(s)Hybridization20302140312250N/A41N/A32N/A23N/A60N/A51N/A42N/AExplain why the bond angle decreases as the number of non-bonded pairs on the central atom increases.417957013335000Electromagnetic radiation is commonly used to study atoms and molecules. What type of electromagnetic radiation is used to study the following?Electronic transitionsIonizationMolecular Vibrations Electronic transitions are studied using the UV/Vis range of EMR. Which type of motions, vibrational or electronic, requires the greatest energy? Justify your answer. The structural formula for the amino acid, glycine is shown. Indicate the structure, hybridization, and bond angles for all elements numbered. Justify your answer in each case.What is Beer’s law and how is it commonly used to study molecules?Molecules that have alternating (conjugated) double bonds absorb visible light (you should know this fact for test). What ions are colored and form solutions that absorb visible light? Justify your answer.Use the data below (excel or calculator) to make a Beer’s Law plot, write down the equation of the line, and calculate the molarity of the unknown solution. (9.01e-5 M)MolarityAbsorbance7.817e-50.11.782e-40.1882.7817e-40.2723.7817e-40.434.7817e-40.4695.7818e-40.566unknown0.111Calculate the molar absorptivity () of the substance assuming the path length of the cuvette was 1 cm.Which of the following pairs of bonded atoms would be expected to have the longest bond length?C-NB. C-SC. C-B D. C-FWhich of the descriptions below is the best representation of the energy change involved in the process of breaking bonds in a molecule? (ignore any subsequent bond formation that may occur)Always exothermicAlways endothermicNet energy change is zeroExothermic or endothermic depending on conditions.How many sigma (σ) and pi(π) electron pairs are there in a carbon dioxide molecule?Two sigma, zero piOne sigma, one pi Two sigma, two piTwo sigma, one piWhich of the following elements is most likely to form compound involving an expanded valence shell of electrons?PB. NaC. OD. NWhich of the following statements best describes the relationship between bond length and bond strength for a series of compounds involving bonds between the same two atoms?The greater the bond strength, the longer the bond.The greater the bond strength, the shorter the bond.Bond length and bond strength are not relatedThe relationship between bond length and bond strength depends on other factors.Which of the following combinations of two elements is most likely to produce highly ionic bonds?Nitrogen and oxygenNitrogen and fluorineBoron and nitrogenLithium and fluorineWhich of the following combinations of two elements is most likely to produce covalent bonds?nitrogen and oxygenoxygen and calciumsodium and nitrogenlithium and fluorineWhich of the following salts is expected to have the highest melting point?NaFC. NaINaClD. NaBrPredict which compound in each of the following pairs should have the higher melting point.NaCl or RbCl(ii) NaCl or MgCl2Draw Lewis dot structures for the following:AmmoniaHydrogen cyanideN2OBrF5Ca3(PO4)2Based on the VSEPR theory, what is the molecular shape of PCl5?LineartetrahedralTrigonal planarTrigonal bipyramidalBased on the VSEPR theory, which of the following corresponds most closely to the molecular shape of SCl2?Linear“T-shaped”bent (bond angle 120o)bent (bond angle 109.5o)A certain molecule has five structural electron pairs and the molecular structure is linear. How many lone pairs are present in this molecule?NoneC. TwoOneD. ThreeA certain molecule has six structural electron pairs and the molecular structure is a square pyramid. How many lone pairs are present in this molecule?NoneC. twoOneD. threeWhat is the approximate Cl-B-Cl angle in BCl3?90oC. 120o109.5oD. 180oWhat is the approximate I-I-I angle in I3─?90oC. 120o109.5oD. 180oWhich of the following best describes the variation of electronegativity of the elements with respect to their position on the periodic table?Increases across a period, increases down a groupIncreases across a period, decreases down a groupDecreases across a period, increases down a groupDecreases across a period, decreases down a groupWhat is the formal charge on the O atoms in SO32─?0B. +1C. -1 D. +2459486011747500What is the formal charge of the S atom in SO3?0B. +1C. -1 D. +2What is the average carbon-oxygen bond order in the formate ion?OneC. Two1 ? D. 2 ?What is the average sulfur-oxygen bond order in SO3?OneC. Two?D. 1 1/3In which species is the carbon-oxygen bond longer? 311848522225008007353365500 B. Given the bond dissociation energies below, calculate the standard molar enthalpy of formation of NF3 (in KJ/mol).? N2(g) + 3/2 F2(g) NH3(g)BondDissociation Energy (KJ/mol)N≡N946F─F159N─F272833C. -104440.D. -578Which of the bonds below is least polar?C─OC. C─NC─FD. C─BWhich of the following molecules is polar?NCl3C. SF6O2D. CS2Which of the following molecules is most likely to have a dipole moment?CH4C. SF6BeF2D. NF3Cyanic Acid has the electron dot structure below (you must add non-bonding pairs of electrons):H─O─C≡NHow many sigma (σ) bonds are there? How many pi(π) bond are there? What is the value of the C─O─H angle? What is the value of the N─C─O angle? Which of the following elements is most likely to display sp3d hybridization?OxygenC. PhosphorusNitrogenD. CarbonWhat type of hybrid orbital set is used by the nitrogen atom in the molecule NH3?sp B. sp2 C. sp3 D. sp3d2What type of hybrid orbital set is used by the xenon atom in the compound XeF4?sp B. sp2 C. sp3 D. sp3d2What hybrid orbital set is used by the nitrogen atom in the following molecule? You must add non-bonded pairs of electrons.H3C─N═C═Osp B. sp2 C. sp3 D. sp3d2BONDING FUNCTION PURE Explain all of the variables in Coulomb’s law as it applies to intermolecular forces.What is the difference between a “bond” and an “intermolecular force”? Do you think an AP reader would give you credit if you used these words interchangeably? Why or why not?Identify the force of attraction that must be broken for the following substances. If the force of attraction is an intermolecular force, list all IMF’s involved. Please do not use “LD”, “HB” etc – spell it out! AP won’t accept acronyms unless they are defined first.SubstanceCovalent, Ionic, Metallic, or IMF?If IMF, which one(s)BrassNH3C6H12O6HClSiO2SiCaCl2PCl3(an amino acid)NaNaClC3H6Answer the questions below regarding hydrogen iodide and iodine.Identify the intermolecular forces present in each of the pure substances.The melting points are -50.80oC for HI and 113.7oC for I2. Explain the large difference using bonding and intermolecular forces.Below is a table of the vapor pressure at 20oC for a variety of substances.Pvapor at 20oC (KPa)Pentane57.902-pentanone3.6 1-pentanol0.200butane203Use intermolecular forces to explain the trend observed among the three 5-carbon substances. (You may want to look up their structural formulas online)Use intermolecular forces to explain the difference between butane and pentane.Use molecular structures to model both hydrogen-bonding possibilities in water. Label each atom with partial charges.Predict which substance is likely to have the highest boiling point in each of the following pairs. Justify your answer using Coulomb’s law.Na2O or CaOc. KF or KClSrO or CaOd. RbCl or SrBr2FOCUS ON GASESConceptualList the five premises of kinetic molecular theoryExplain the following phenomenon using kinetic molecular theory.An increase in pressure at constant T & n results in a decrease in the volume of a gas.An increase in temperature at constant P & n results in an increase in the volume of a gas.An increase in temperature at constant V & n results in an increase in the pressure of a gas.Answer the questions below regarding the following gas cylinders. Justify your answer in each case.Which cylinder has the gas molecules with the highest kinetic energy?Which cylinder has the gas molecules with the highest average velocity?Which gas is most likely to condense first as temperature is decreased or pressure is increased? Which cylinder has the lowest density of gas?Each of the cylinders above has a volume of one liter. All the gases are combined into a new cylinder with a volume of 2 liters and then the temperature is lowered to 273 K. What is the total pressure in the flask? (2.33 atm)Two students are at opposite ends of a 24 inch glass tube. Simultaneously, one places a cotton ball soaked in HCl in her end and the other places a cotton ball soaked in NH3 in his end. When the two vapors meet a smoky ring of solid NH4Cl forms. Will the smoky ring form closer to the male student or the female student? Justify your answer (hint – Graham’s Law)MathematicalA bubble of carbon dioxide gas in some unbaked bread dough has a volume of 1.15 cm3 at a temperature of 22°C . What volume will the bubble have when the bread is baked and the bubble reaches a temperature of 99°C? (1.45 cm3)A container filled with helium gas has a pressure of 127.5 kPa at a temperature of 290. K. What is the temperature when the pressure is 3.51 kPa? (7.98 K)A sample of nitrogen gas is collected over water, yielding a total volume of 62.25 mL at a temperature of 22°C and a total pressure of 97.7 kPa. At what pressure will the nitrogen alone occupy a volume of 50.00 mL at the same temperature? (118 KPa)The theoretical yield of a reaction that gives off nitrogen trifluoride gas is 844 mL at STP. What total volume of NF3 plus water vapor will be collected over water at 25°C and a total pressure of 1.017 atm? (935 mL)What is the density of silicon tetrafluoride gas at 72°C and a pressure of 144.5 kPa? (5.24 g/L)An unknown gas has a density of 0.0262 g/mL at a pressure of 0.918 atm and a temperature of 10.°C. What is the molar mass of the gas? (663 g/mol)A student collects ethane by water displacement at a temperature of 15°C (vapor pressure of water is 1.5988 kPa) and a total pressure of 100.0 kPa. The volume of the collection bottle is 245 mL. How many moles of ethane are in the bottle? (0.0101 mol)A reaction yields 3.75 L of nitrogen monoxide. The volume is measured at 19°C and at a pressure of 1.10 atm. What mass of NO was produced by the reaction? (5.16 g)A reaction has a theoretical yield of 8.83 g of ammonia. The reaction gives off 10.24 L of ammonia measured at 52°C and 105.3 kPa. What was the percent yield of the reaction? (77.0 %)Diethyl ether burns in air according to the following equation. If 7.15 L of CO2 is produced at a temperature of 125°C and a pressure of 1.02 atm, what volume of oxygen, measured at STP, was consumed and what mass of diethyl ether was burned? (7.50 L O2 at STP; 4.14 g diethyl ether)C4H10O(l) + 6O2(g) 4CO2(g) + 5H2O(l)BONDING FUNCTION MIXTURE Dissolving and mixing always involves an increase in entropy. Despite this favorable change, not all substances mix or dissolve due to unfavorable energetics. For each of the following pairs, indicate the forces of attraction that must be broken and formed in order for the two to mix. PAIRBROKENFORMEDNET ENERGY PREDICTIONWater and ethanolWater and benzeneWater and copper(II) sulfateBenzene and cyclohexaneUse coulombs law to explain why the aluminum ion, Al3+, has a greater attraction to water than the gallium ion, Ga3+.Use structural formulas to show ethanol hydrogen bonding with water molecules. Make sure to show all possibilities. Include partial charges on each atom.Differentiate between P-type doping and N-type doping of silicon. Provide an example of each.Differentiate between interstitial and substitutional alloys. Look up an example of each and list how properties changed in the alloy compared to the pure metal.How does the radius of a metal atom solute affect the hardness of the metal solvent in alloys?REACTIONSWhat is characteristic of reactions that can be described by net ionic equations? What classifications (decomposition, synthesis, combustion, double replacement, single replacement, neutralization, redox) are often described by net ionic reactions?When potassium chlorate is decomposed, a gas forms that is able to re-ignite a glowing splint. Write the balanced reaction for the decomposition.Write the balanced chemical reactions (including units) for the following:Solutions of iron(III) perchlorate + calcium hydroxide.A piece of copper is added to a solution of lead(II) nitrate.Nitrous acid + aqueous potassium hydroxideWrite net ionic equations for the reactions in #3.Write the balanced reaction equation for the combustion of the following substancesC3H6C6H6C5H9OHDraw a particle diagram showing the synthesis reaction between nitrogen monoxide gas and oxygen gas to form nitrogen dioxide. Use 5 molecules of oxygen in your drawing.KINETICSList the three premises of collision theory.What experimental factors increase the rate of a reaction? Explain why in terms of collision theory.Define the following terms:MechanismIntermediateCatalystRate constantRate constant expressionMolecularity (unimolecular, bimolecular, termolecular)Rate determining step.OrderInitial rateInstantaneous rateAverage rateThe following mechanism has been proposed for the formation of NOBr:Step 1: NO(g) + Br2(g) ? NOBr2(g) (fast)Step 2: NOBr2(g) + NO(g) 2NOBr(g) (slow)Write the overall balanced equation for this reaction.Derive the rate law expression predicted by this mechanism.Why is this reaction not likely to occur in one step?For the reaction that follows what is [NO2]/t with respect to [NO]/t? 2NO(g) + O2(g) 2NO2(g)Given the initial data for the reaction A + B C, determine the rate expression for the reaction. The reaction is catalyzed by molecule “D”. Calculate “k” as well.[A] (M)[B] (M)[D] (M)[C]/t (M/s)0.100.200.102.580.100.100.101.290.240.100.202.580.100.200.205.16 Hydrogen peroxide decays into water and oxygen in a first-order process,H2O2(aq) H2O(l) + ? O2(g)Where the rate expression is ?[H2O2]/ t = k[H2O2]. If we begin with 0.100 M H2O2 and find that after 3200 seconds the peroxide concentration falls to 0.0825 M, what is the rate constant, k, at the temperature at which the experiment is performed? (6.01 x 10?5 s?1)The decomposition of SO2Cl2 is first order in SO2Cl2 with a rate constant of 0.17 hr─1. What is the half-life of SO2Cl2? (4.1 hours)We know that the half-life for the first-order, radioactive decay of 222Rn is 3.82 days. If we have 5.80 micrograms of 222Rn, how much will remain after 21.2 days?(1.27 x 10─7)We are studying the reaction A 2B. A plot of 1/[A] vs. time as the reaction proceeds is linear with a slope of 0.187 M─1s─1. What is the rate expression for the reaction?The reaction I─ + OCl─ IO─ + Cl─ is first order with respect to I─ and first order with respect to OCl─. The rate constant is 6.1 x 10─2 L/mol-s. What is the rate of reaction when [I─] = 0.10 M and [OCl─] = 0.20 M? (1.2 x 10─3 M/s)47091606223000What fraction of a reactant remains after 3 half-lives of a first order reaction?At what point on the potential energy diagram shown does the transition state (activated complex) occur? The rate of the chemical reaction between substances A and B is found to follow the equation? rate=k[A]2[B],? where k is a constant. If the concentration of A is halved, what should be done to the concentration of B to make the reaction go to 75% of its former rate?? The concentration of B should be kept constant? The concentration of B should be doubled? The concentration of B should be tripled? 570420512319000The concentration of B should be halved? The concentration of B should be multiplied by 4/3.?Answer the following questions regarding the potential energy curve shown. Justify all answers.How many steps are in the mechanism for this reaction?Which step is the rate determining step?Which letter(s) represent intermediates?Which letter(s) represent activated complex(es)?Is the overall reaction endothermic or exothermic?EQUILIBRIUMGeneral EquilibriaExplain the term “dynamic equilibrium”.Define the reaction quotient, Q.What is the difference between the reaction quotient “Q” and the equilibrium constant “K”.Which of the following changes the value of an equilibrium constant. Justify your answer in each case.TemperatureConcentration of productsCatalystConcentration of reactantsNature of the reactionGiven the following two equilibria, calculate the equilibrium constant for the third (2.1)PbI2(s) ? Pb2+(aq) + 2I-(aq)K1 = 8.7 x 10-9PbSO4(s) ? Pb2+(aq) + SO42-(aq) K2 = 1.8 x 10-8PbSO4(s) + 2I-(aq) ? PbI2(s) + SO42-(aq) K3 = ??Given the equilibrium constant, Kp, for the following reaction at 250C, calculate the equilibrium constant, Kc, for the same reaction at the same temperature. (R = 0.0821) (6.1 x 10-3)N2O4(g) ? 2NO2(g) Kp = 0.15Determine if the following system is at equilibrium, the reactant concentrations are too high, the product concentrations are too high, or if one simply cannot determine with information given:PCl5(g) ? PCl3(g) + Cl2(g)Kp = 11.5PPCl5=1.15 atmPPCl3=5.30 atmPCl2=2.80 atmThe equilibrium constant for the reaction: SO2(g) + NO2(g) ? SO3(g) + NO(g) has a numerical value of 3.00 at a given temperature. Equimolar amounts of SO2 and NO2 are reacted at this temperature and a total pressure of 3.00 atm. What percent of the SO2 is converted to product? (63.4 %)For which of the reactions will an increase in pressure cause a decrease in product (temperature remaining constant)? Justify your choices.N2(g) + 3H2 (g) ? 2NH3(g)3Fe(s) + 3H2O(g) ? Fe2O3 (s) + 3H2(g)PCl3(g) + Cl2(g) ? PCl5(g)HCl(g) + H2O(l) ? H3O+ (aq) + Cl-(aq)CaCO3(s) ? CaO(s) + CO2(g)Consider the equilibrium reaction: SO2(g) + O2(g) ? SO3(g) What will be the effect of doubling the concentration of SO3? Justify you answer(s)SO2 and O2 increase equallySO2 increases more than that of O2O2 increases more than that of SO2SO2 decreases more than that of O2O2 decreases more than that of SO2The synthesis of hydrogen sulfide gas is given by the following: H2 (g) + S (s) ? H2S (g) + energy. List all of the “stresses” that would increase the mass of sulfur. Justify your answer in each case.For each of the following “stresses” on the equilibrium system, N2O4(g) ? 2NO2(g), indicate how the stress alters the forward and/or reverse rates (are they increased or decrease or unaffected?) ?H = 57.2 KJForward rateReverse rateShift in response to stressJustificationTemperature is increasedN2O4 is decreasedNO2 is decreasedN2O4 is increasedNO2 is increasedA catalyst is addedThe volume is decreasedHelium is added at constant volumeWhat must be true of a reaction in order for Kc = Kp?Indicating Drierite is a material used in the laboratory to remove water vapor from gases and as a dessicating agent. When purchased, it is blue in color and it changes to pink upon absorbing moisture. Based upon your observations in the LeChatelier lab, explain how Indicating Drierite works.Blue Drierite + H2O ? Pink Drierite + heatIndicating Drierite can be regenerated and used over and over again. Propose a method of regenerating Drierite quickly, efficiently, and at low cost. Explain how your method will work, using Le Chatelier’s principle.Nickel forms a green complex ion, [Ni(H2O)6]2+, in water. The addition of a small amount of ethylenediamine (en) results in a light blue–colored solution. Ethelynediamine is a bidentate ligand, meaning it bonds to metals through two atoms of the ligand. Further addition of ethylenediamine results in a royal blue solution while the addition of even more ethylenediamine gives a violet solution. Further addition produces no additional color changes.Propose a series of equilibrium reactions that would illustrate the observations.Predict the effect of adding solid nickel(II) nitrate to the violet solution. Explain your answer using Le Chatelier’s principle.Solubility EquilibriaFor slightly soluble salts, if Q < K is the solution saturated, unsaturated, or supersaturated? Justify your answer.For slightly soluble salts, if Q > K, would the mass of the precipitate increase or decrease? Justify your answer.Write the dissociation reactions and Ksp expressions for the following slightly soluble salts. Write Ksp in terms of the solubility, S. The first one has been done for you as a model.SALTDISSOCIATION REACTIONEQUILIBRIUM CONSTANT EXPRESSIONKsp in terms of “S”Cd(OH)2Cd(OH)2(s) ? Cd2+(aq) + 2OH─(aq)Ksp = [Cd2+][ OH─]2Ksp = 4S3CoCO3LaF3Hg2SBa3(PO4)2Calculate the molar solubility and g/L solubility values for Cd(OH)2 (Ksp = 2.5 x 10-14) and Ba3(PO4)2 (3.4 x 10-23).In the above example: Will the addition of Na3PO4 increase or decrease the solubility of barium phosphate at a given temperature? Justify your answer.Lead(II) carbonate has a Ksp= 7.4 x 10-14 and lead(II) hydroxide has a Ksp = 1.2 x 10-15. Calculate the molar solubility for each of these compounds. Can the magnitude of Ksp be used to predict solubility? Explain.The solubility of copper (II) iodate in water is 3.27 x 10-3 M. What is the Ksp? (1.40 x 10-7)A 10.0 mL solution is 0.10 M with respect to both calcium nitrate and magnesium nitrate. Which salt begins to precipitate first if 0.10 M NaF is added by drops? (Ksp CaF2= 4.0 x 10-11 & Ksp MgF2 = 6.4 x 10-9) Justify your answer.Which ions will remain in solution if excess magnesium nitrate is added to sodium fluoride? Rank the ions in order of relative abundance in the solution.ACIDS AND BASESIndicate whether each of the following pairs represent conjugate pairs (acid/CB 0r base/CA). Justify your answer in each case.H2C2O4 & C2O42-H2PO4- & HPO42-CH3NH2 & CH2NH2H3O+ & OH-This reaction is reversible. Identify all acids and bases. HSO3- + H2O ? SO32- + H3O+Answer the follow questions regarding the titration curve. Justify your answer in each case.Which point is the best for determining whether the acid is strong or weak?Why is the equivalence point basic? Which point(s) represent a region of buffering? 34417003365500After which point is the acid primarily in its deprotonated form?At which point is the pH determined from the amount of sodium hydroxide? From which point can the Ka of the acid be determined?What two factors determine the starting pH in a titration?If the acid were HCN, which ions would be present in the solution at the “X”? Draw a particulate diagram to show the relative amounts.Use the data from the titration curve to determine the molarity of the acid.428625089154000An indicator was used that changed color so that the endpoint was slightly sooner than the equivalence point, would the calculated molarity from the endpoint be too high or too low? Sketch the curve for a strong acid of equal molarity. What are the three main differences in the curves?Sketch the curve observed for the weak acid if the molarity of the sodium hydroxide is doubled.Since ions are formed and consumed during a titration, it is sometimes possible to measure conductivity instead of pH. This approach can be used when titrating barium hydroxide with sulfuric acidWrite the reaction for the dissociation of barium hydroxide. Write the balanced, net ionic equation for the reaction of barium hydroxide with sulfuric acid.Why does the conductivity decrease at the beginning of the titration?Why does the conductivity increase after the equivalence point?You are given 4.554 g of a mixture of oxalic acid, H2C2O4, and sodium chloride. If 29.58 mL of 0.550 M NaOH are required to titrate the 4.554 g sample to the equivalence point, what is the mass percent of oxalic acid (MM = 90.04 g/mol) in the mixture? (16.1%)H2C2O4 + 2NaOH Na2C2O4 + 2H2O Knowing that HF is a stronger acid than HC2H3O2, determine, if possible, in which direction the following equilibrium lies: HF + C2H3O2─ ? F─ + HC2H3O2LeftB. RightC. Perfectly balancedD. Cannot be determinedAt 50oC the water ionization constant, Kw is 5.48 x 10-14. What is [H3O+] in neutral water at 50oC? (2.34 x 10-7 M)We have a 0.00100 M solution of Sr(OH)2 solution at 25oC. What is [H3O+] in this solution? (5.00 x 10-12 M)We have a 5.43 x 10-4 solution of HNO3 at 25oC. What is [OH─] in this solution? (1.84 x 10-11 M)We have 500. mL of a solution that contains 0.0854 g of NaOH. What is the pH of this solution at 25oC? (11.63)For each solution below, tell if the pH is < 7, pH = 7 or if pH > 7. JUSTIFY0.10 M HNO30.012 M KOH0.15 M acetic acid0.56 M Na2CO30.45 M KBrPredict the products of the following acid-base reaction: NH3+ HNO3The following reactants are mixed in equimolar portions. Predict the resulting solution will be (A) acidic, (B) Basic, (C) neutral (D) cannot be determined.HCl + NaHCO3 ?HCl + NaOH ?HF + KOH ? H2SO4 + KOH ?CH3COOH + NH3 ? (HINT: look up “K” values)Indicate whether the following describes and acid, base, or bothDonates H+ Solution conducts electricityTurns litmus paper redPink with phenolphthaleinReacts with active metalsTastes bitterFeels slipperyWhich of the following substances is amphoteric? JUSTIFYAl(OH)3D. Ca(OH)2HCNE. HICsBr Which of the following substances is amphoteric? (Select all correct answers) JUSTIFYSO42─C. H2PO42─H2OD. H2SO4In which of the following is the acid strength ranking INCORRECT? JUSTIFY your choice.H2SO4 > H2SO3HNO3 > HNO2HClO4 > HClO3HClO3 > HBrO3H2SeO3 > H2SO3Rank the hydrohalic acids from strongest to weakest: JUSTIFYHF > HCl > HBr > HIC. HCl > HBr > HI > HFHI > HBr > HCl > HFD. HF > HI > HBr > HClRank the chlorine based acids from strongest to weakest. JUSTIFYHClO > HClO2 > HClO3 > HClO4HClO4 > HClO3 > HClO2 > HClO Which of the following is the strongest acid? JUSTIFYHClO3C. HClO2HBrO2D. HBrO3Which of the following is the strongest acid? JUSTIFYH3AsO4C. H3AsO3H3PO4D. H3PO3We have a solution of NH3. What effect will the addition of HCl have on the pH of the solution? JUSTIFYIncrease pHB. Decrease pHC. no effectEQUILIBRIA, BUFFERS, TITRATIONS – YOU WILL NEED TO LOOK UP APPROPRIATE Ka AND KbWhat is the pH of a 0.155 M solution of H2S at 250C? (3.90)What is the [OH─] in a 0.10 M solution of NaCN at 25oC? (1.57 x 10-3 M)What is the pH of a 0.144 M solution of NaF at 25oC? (8.15)If the pH of a 0.015 M solution of hypochlorous acid is 4.64, what is the concentration of the hypochlorite ion, OCl─, in solution? (2.29 x 10─5 M)What is the value of Ka for hypochlorous acid from the previous question? (3.50 x 10─8)We mix 50.0 mL of 0.050 M HNO3 and 25.0 mL of 0.10 M NaCH3COO. What is the pH of the resulting solution? (3.11)We add 1.00 mL of 10.0 M NaOH to 50.0 mL of 0.20 M HNO2. What is the pH of the resulting solution? (8.32)We have 100. mL of a 0.10 M solution of CH3COOH. How many grams of NaCH3COO must be added to make a buffer solution of pH 5.00? Ka acetic acid = 1.8 x 10─5 (1.48 g)A 0.10 M solution of HF is 8.1% ionized. What is the Ka? (7.1 x 10─4)A 1.50 g sample of vitamin C is dissolved in 100.0 mL of water and titrated with 0.250 M NaOH to the methyl orange end point. The volume of the base used is 34.1 mL. What is the molar mass of Vitamin C assuming one dissociable proton per molecule? (176 g/mol)A 25.00 mL sample of 0.100 M HCl is titrated with 0.100 M NaOH. What is the pH of the solution at the points where 25.1 and 25.5 mL of NaOH have been added? (10.30, 11.00)A 25.00 mL sample of 0.100 M CH3CO2H is titrated with 0.100 M NaOH. What is the pH of the solution at the points where 24.5 and 25.5 mL of NaOH have been added? (Ka = 1.8 x 10-5) (6.43, 11.00)Which of the following mixtures will be a buffer when dissolved in a liter of water?1. 0.2 mol Ba(OH)2 and 0.3 mol HClO22. 0.2 mol KNO3 and 0.2 mol HClO33. 0.4 mol NH4Cl and 0.4 mol NaOH4. 0.2 mol HClO3 and 0.1 mol LiOH5. 0.4 mol HCOOH and 0.2 mol NaOH THERMOCHEMISTRY & THERMODYNAMICSDefine the following terms.State FunctionInternal EnergyWorkheatEnthalpyEntropyFree energyspontaneousThermodynamically favorableHeat capacitySpecific heat capacityEnthalpy drivenEntropy drivenEnthalpy of formationFree Energy of formationStandard “positional” entropySATPEndothermicExothermicSystemSurroundingsCalorimetryDescribe and explain what happens to the temperature of the surroundings during an exothermic process.Describe and explain what happens to the temperature of the surroundings during an endothermic process.ELECTROCHEMISTRY ................
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