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2136140-711200 G C S E C H E M I S T R Y N O T E S Topics-1. Hazard Symbols2. Man-Made Materials3. Composite Materials4. Gases5. Solubility6. Kinetic Theory7. Atomic Structure8. Elements, Compounds & Mixtures9. Bonding10. Chemical Nomenclature11. Rusting12. Redox13. Hard Water14. Acids & Bases15. Electrolysis16. Energetics17. Reactivity Series18. Reaction Rates19. Periodic Table20. Chemical Calculations 21. Metals22. Non-Metals23. Organic Chemistry24. Human Influences25. Industrial Processes26. Radioactivity 1. Hazard SymbolsIn any chemical catalogue or any bottle of chemical you should be warned about the potential dangers of a chemical.Hazard Symbols are used to warn of potential dangers of a chemical.Hazard symbols are used because-Internationally AgreedEasily RecognisedFlammable- Liquids which have a flash point equal to or greater than 21? and less than or equal to 55?Toxic- Substances which present a series risk of acute or chronic poisoning by inhalation, ingestion or skin absorptionCorrosive- Substances which destroy living tissueExplosive- Substances which may explode under the effect of flame or heat or shock/frictionHarmful- Substances which present moderate risks to health by inhalation, ingestion or skin absorptionIrritant- Substances which are non-corrosive but are liable to cause inflammation through immediate, prolonged or repeated contact with the skin.Table 1: Chemical Symbols2. Man-Made MaterialsMaterials can be classified as Natural or Man-Made. Materials can also be classified further into five categories-MetalsCeramicsGlassPlastics- Thermosoftening and ThermosettingFibresThermosoftening & Thermosetting PlasticsThermosofteningThermosoftening plastics are flexible and can be moulded into different shapes. This is because long chains in the polymer can-Figure 1: Thermosoftening plastic with no bonds353476019137Stretch easilySoften on warmingAre flexibleCan be shaped on warningThermosettingThermosetting plastics are strong, rigid and once formed do not soften or melt. Figure 2: Thermosetting plastics with bonds3644900153670The long chain molecules are joined by cross-links and when the chains are heated the crosslink’s stop movement. Properties of MaterialsGroups of MaterialsExamplesProperties of MaterialsMetalsCopper, Aluminium, Iron, Lead, ZincConduct Electricity, Conduct Heat, Malleable, Ductile, High Melting PointCeramicsPottery, TilesBrittle, High Melting PointGlassSoda Glass, PyrexBrittle, High Melting Point, TransparentFibresNylonFlexible, Low Melting PointPlasticsThermosetting- Bakelite, Melamine, Epoxy ResinBrittle, High Melting Point, Electrical InsulatorsThermosoftening- Polythene, PVC, Polystyrene Flexible, Can be Moulded, Low Melting Point, Electrical InsulatorsTable 2: Properties of Materials & ExamplesHardness- How easy it is to scratch or dent a material. A harder material will always scratch a softer material. Brittle- A brittle material will shatter if dropped on a hard floor. Brittle materials such as glass or ceramics cannot absorb the energy of a large collision without cracking or shattering totally.Strength- A material which is difficult to break when a force is applied. Strength is usually associated with a stretching force. 271145880110Flexibility- A flexible material is one that is easy to bend without breaking. Flexible materials have good tensile strength and compressive strength. 2393956542405176530277431581915-220980Uses of MaterialsIn deciding suitable materials we must ask ourselves these questions-Are the physical properties suitable?Are the chemical properties suitable?Is the cost of the material suitable?MaterialUsePropertyIronBridgesHigh StrengthAluminiumSaucepansGood Conductor of HeatCopperElectrical WiringGood Conductor of ElectricityLeadRoofingMalleableZincGalvanising IronChemically more reactive than ironMelamineKitchen WorktopsHigh Heat ResistancePolytheneBottlesEasy to melt and mould365760167640Table 3: Some uses of Materials3. Composite MaterialsA Composite Material is one which combines the properties of more than one material to produce a more useful material for a particular purpose. In a composite material, one of the materials is used as a matrix while the other acts as a posite materials are not just synthetic but natural also. Natural Composites include bone, ivory and teeth. The four composite materials needed are listed below-CompositeMaterials presentAdvantagesUsesReinforced GlassGlass matrix reinforced with wire meshStronger and less brittle than glassWindows and DoorsReinforced ConcreteConcrete matrix reinforced with steel rodsHard like concrete with the flexibility and strength of steelConstruction industry, for buildingsGlass-reinforced plasticPlastic matrix reinforced with glass fibre mattingFlexible like plastic. Much stronger than plastic and less brittle than glassBoats, car bodies and canoesBoneCalcium phosphate reinforced with protein fibresHard like calcium phosphate but more flexible than calcium phosphateSkeletonTable 4: Composite Materials and Advantages4. GasesDiffusionDiffusion provides us with evidence that the particles of a gas can move and it is described as the movement of particles from a region of high concentration to a region of lower concentration.The coloured particles diffuse quickly into the air particles and as the same time, the air particles diffuse into the coloured particles.Diffusion in liquids is much slower as particles in a liquid move more slowly than those in gas. 339269619494533978851770380 Figure 3: Diffusion of Bromine and the Diffusion of Potassium PermanganateSpeed of DiffusionThe ring of white powder is closer to the HCL than the NH3. This is because the NH3 molecules are lighter (smaller) and have diffused more quickly through the air in the tube.Effect of Temperature & PressureAs pressure increases, at a given temperature, volume will decrease.As pressure decreases, at a given temperature, volume increases.As temperature increases, at a given pressure, volume increases.As temperature decreases, at a given pressure, volume decreases.PV/T = ConstantP1 ×V1T1=P2 ×V2T2Pressure is measured in Pascals (Pa).Temperature is measured in Kelvin. To work out Kelvin, add 273 to °c temperature.Volume is measured in Cubic Metres (m3).80 cm3 of oxygen in a gas syringe at 27°c and a pressure of 12 000 Pa. The gas was then heated to 87°c at a new pressure of 18 000 Pa. What is the volume of oxygen under the new conditions?>(12000 ×80)300=(18000 ×V2)360> V2= (12000 ×80 ×360)(300 ×18000)> V2=64cm35. SolubilitySolubility: the amount of a solute that can be dissolved in a certain amount of solvent.Solubility of a solute in a solvent – measured in: grams of solute per 100 grams of solvent at a particular temperatureSolubility of most solid solutes increases with temperature.Solute = SolidSolvent = LiquidSolution = MixtureSolubility EquationGrams of Solute × 100Grams of Solvent=x g /100g waterSolubility Curve388620064135This allows us to plot a graph after working out solubility at different temperatures. The graph allows us to work out-The solubility at a given temperatureThe temperature at which the solution will saturate and produce crystalsThe mass of crystals which will form when the solution is cooled to a lower temperature6. Kinetic TheoryTable 5: The Important Properties of solids liquids and gasesPropertySolidsLiquidsGasesShapeStay the SameTake the shape of the ContainerTake the shape of the ContainerVolumeStay the SameStay the SameTake the volume of containerDensityHigh DensityMedium DensityLow DensityCompressibilityCannotCompressed SlightlyCan be compressed into smaller volumesChanges in StateMeltingWhen a solid is heated, particles gain energy causing them to vibrate faster and faster about fixed positions.When sufficient energy is gained, the particles break away and the solid melts.Melting is endothermic as it takes in energy to melt. Boiling and EvaporationWhen a liquid is heated the particles gain energy and move around faster.Before reaching boiling temperature, some of the higher energy particles will have enough energy to overcome the attractions to escape and form a gas, evaporation. On further heating all particles gain sufficient energy to overcome the attractive forces and the liquid boils. These are endothermic.Condensation and FreezingThese are exothermic reactions so give out energy.During cooling, the gas particles lose energy and are able to move closer together until condensation takes place. When particles of a liquid are cooled, the particles move closer and form strong attractive forces for freezing to take place.SublimationSublimation takes place when a solid goes directly from a solid to a gas or from a gas to a solid. Solid carbon dioxide (dry ice) and iodine crystals are examples.7. Atomic StructureElement: Any substance that cannot be broken down into a simpler one by a chemical pound: A substance formed by the chemical combination of elements.Atom: The?atom?is a basic unit of matter that consists of a dense central nucleus surrounded by a cloud of negatively charged electrons.Ion: An atom or group of atoms that has acquired an electric charge by losing or gaining one or more electrons.Atomic Number: The number of protons in an atom of that element.Mass Number: The number of protons and neutrons in the nucleus of an atom of that element.ParticleRelative MassRelative ChargePositionNeutron10NucleusProton1-1NucleusElectron11840-1ShellStructure of the first twenty elementsElementAtomic No.Mass No.No. ProtonsNo. ElectronsNo. NeutronsHydrogen11110Helium24222Lithium 37334Beryllium49445Boron511556Carbon612666Nitrogen714777Oxygen816888Fluorine9199910Neon1020101010Sodium1123111112Magnesium1224121212Aluminium1327131314Silicon1428141414Phosphorus1531151516Sulphur1632161616Chlorine1735171718Argon1840181822Potassium1939191920Calcium2040202020IsotopesIsotopes are the atoms of an element with different numbers of neutrons. They have the same proton number, but different mass numbers.IsotopeProtonsElectronsNeutrons35 17 Cl17171837 17 Cl1717201 1 H1102 1 H1113 1 H112isotopesymbolhydrogen-11 proton, 0 neutron, 1 electron692150-55880hydrogen-21 proton, 1 neutron, 1 electron692150-55880hydrogen-31 proton, 2 neutrons, 1 electron7683501270Figure 4: Three Isotopes of Hydrogen8. Elements, Compounds & MixturesMetallic & Non-Metallic ElementsMetallic ElementsNon-Metallic ElementsGood conductors of electricityPoor Conductors of electricityGood conductors of heatPoor conductors of heatAll are solids at room temp. Can be gas, liquid or solid at room temp.High DensityLow DensityHigh melting + boiling pointsLow melting + boiling pointsMalleable + ductileSoft + brittleShiny solidsUsually dullCompounds & MixturesCompounds are substances which contain two or more elements chemically joined together.A mixture can be defined as consisting of two or more substances that are usually easy to poundMixtureIs a pure substanceTwo or more substancesChemical reaction occurs when a compound is formed and there is an energy changeNo chemical change takes placeComposition is always the sameComposition of a mixture can varyProperties are different to those of elements which make it upProperties are same as the elements which make it upDifficult to separate and only broken down by chemical meansEasy to separate by physical means9. BondingSome atoms are very reluctant to combine with other atoms and exist in the air around us as single atoms. These are the Noble Gases and have very stable electron arrangements e.g. 2, 2, 8 and 2, 8, 8 because their outer shells are full.All other atoms therefore, bond together to become electronically more stable,?that is to become like Noble Gases in electron arrangement. Bonding produces new substances and usually involves only the 'outer shell' or 'valency' electrons and atoms can bond in?two ways.Ionic BondingIONIC BONDING - By one atom transferring electrons to another atom to form oppositely charged particles called ions which attract each other - the ionic bond.An ion is an atom or group of atoms carrying an overall positive or negative chargeIf a particle, as in a neutral atom, has equal numbers of protons (+) and electrons (-) the particle charge is zero?i.e. no overall electric charge.The proton/atomic number in an atom does not change BUT the number of associated electrons can!If negative electrons are lost?the excess charge from the protons?produces an overall positive ion.3600450325755If negative electrons are gained?there is an excess of negative charge, so?a negative ion is formed.The atom losing electrons forms a positive ion (cation) and is usually a metal.?The atom gaining electrons forms a negative ion (anion) and is usually a non-metallic element. The ionic bond then consists of the attractive force between the positive and negative ions in the structure.The ionic bonding forces act in all directions around a particular ion, it is not directional, as in the case of covalent bonding.Covalent Bonding3543300316865COVALENT BONDING - sharing electrons to form molecules with covalent bonds, the bond is usually formed between two non-metallic elements in a molecule. The two positive nuclei (due to the positive protons in them) of both atoms are mutually attracted to the shared negative electrons between them - the covalent bond. They share the electrons in a way that gives a stable Noble Gas electron arrangement.Metallic Bonding3314700590550Metals form giant structures in which?electrons?in the outer shells of the metal atoms?are free to move. The metallic bond is the force of attraction between these free electrons and metal?ions. Metallic bonds are strong, so metals can maintain a regular structure and usually have high melting and boiling points.Metals are good?conductors?of electricity and heat, because the free electrons carry a charge or heat energy through the metal. The free electrons allow metal atoms to slide over each other, so metals are?malleable?and?ductile.10. Chemical NomenclatureNames of Ionic CompoundsThe name of the chemical compound tells us the elements present. For example, magnesium oxide tells us magnesium and oxygen is present.The name of the metal is always given as the first part of the name, while the non-metal name appears as the second part of the name.To show that it is a compound, the non-metal usually ends in –ide.Reacting ElementsCompound ProducedMagnesium + OxygenMagnesium OxideIron + SulphurIron SulphideSodium + FluorineSodium FluorideSodium + ChlorineSodium ChloridePotassium + BrominePotassium BromideSodium + IodineSodium IodideMagnesium + NitrogenMagnesium NitrideSome ionic compounds end in –ate or –ite; both indicate that oxygen is present along with the metal and non-metal.Formulae of Ionic CompoundsThe whole number ratio in which the ions or atoms exist in the compound.When writing formula use the following rules-Write down the cation and anion present in the compound.Because ionic compounds are neutral, the charges on the cations and anions must cancel out.Formulae of Ionic CompoundsThe number of the formula can be worked out by considering the valences of each atom.Silica, SiO2: Silicon has a valency of 4, oxygen of 2. This means it takes 2 oxygen atoms to combine with 1 silicon atom.Balancing EquationsCaCO3 → CaO + CO2The above equation is balanced. It has the same elements on both sides and the same number of atoms of each element.NaHCO2 → Na2CO3 +CO2 + H2OThe above equation is not balanced. It does have the same elements on both sides but not the same number of atoms of each element. Writing Symbol EquationsAll the elements that appear on the left must appear of the right. Not only must you have the same elements present on both sides, you must also have the same number of atoms of each element.You cannot change the formula of a chemical to get the equation to balance.Example-Reaction: sodium + water → sodium hydroxide + hydrogen1. Write the correct formula: Na + H2O → NaOH + H22. Check the NA: 1 on the left as the NA 1 on the right in the NaOH One on both sides- balanced3. Check the H: 2 on left in H2O 2 on right in NaOH and 2 in H2 Na + H2O + H2O → NaOH + H2Now there are 4 on left and 3 on right, we add another NaOH4. Check the O: 2 on the left, 1 in each H2O 2 on the right, 1 in each NaOH- balanced5. Recheck the Na: 1 on the left in Na 2 on right, 1 in each NaOH We add another Na, there are now 2- balanced6. The final equation is- 2Na + 2H2O → 2NaOH + H211. RustingFe2O3.2H2OAir and Water cause rustWater with no air does not cause rust.Air with no water does not cause rust.Air and Water must be present for rust to form.Rust PreventionThere are many methods to stop rust forming, these include-PaintingOilingGreasingTin-platingGalvanisingSacrificial ProtectionSacrificial protection is when a more reactive metal is placed alongside iron and is corroded before rust. This is used in ships; zinc bars placed on the iron hull react before the iron and slow down rusting.12. RedoxOxidation and Reduction in terms of oxygenOxidation is the gain of oxygen and reduction is the loss of oxygen.Oxidation and Reduction in terms of hydrogenOxidation is the loss of hydrogen and so reduction is the gain of hydrogen.Oxidising and Reducing AgentsAn oxidising agent “does the oxidising” that is it supplies the oxygen or removes the hydrogen.The oxidising agent itself is reduced; it loses oxygen and gains hydrogen.Important Redox ReactionsRusting: When Iron rusts it forms an oxide by gaining oxygen, the iron is oxidised. Water is also bustion of Fuels: Combustion is the reaction with oxygen forming an oxide and releasing energy. This means that when a fuel burns an oxidation is taking place.Extraction of Aluminium and of Iron: Aluminium and iron are found naturally as their oxides. The oxygen is removed to obtain the metal so the aluminium or iron loses oxygen and is reduced.Manufacture of Ammonia: Ammonia is formed by the reaction of nitrogen with hydrogen; the nitrogen is gained hydrogen and is reduced.13. Hard WaterWater that does not lather easily with soap is called hard water. If the water does lather easily it is soft water.When soap is used with hard water, it is hard to form lather and a scum is formed.Hard water will form lather eventually but will use more soap than a sample of soft water.Soapless detergents will lather well with both hard and soft water because it is only soap that reacts to form scum.Causes of Hard WaterSolutionBehaviour with SoapSodium ChlorideGood LatherCalcium ChlorideNo Lather, scumMagnesium ChloridePoor Lather, scumPotassium NitrateGood LatherCalcium NitratePoor Lather, scumMagnesium NitrateNo Lather, scumSodium SulphateGood LatherIt can be seen that only dissolved calcium or magnesium ions make water hard. The calcium or magnesium ions react with soap forming insoluble salts which are precipitated out of the mixture as scum.Ca2+ (aq) + 2C17H35COONa (aq) → (C17H35COO)2Ca (s) + Na+ (aq)Types of Hard WaterTemporary Hard WaterCarbon Dioxide in the air dissolves in rain water forming the week acid, carbonic acid.CO2 (g) + H2O (I) → H2CO3 (aq)When this dilute acidic solutions falls on rocks containing calcium carbonate e.g. limestone, soluble calcium hydrogencarbonate is formed. As a result there is calcium ions dissolved in water and the water is hard.H2CO3 (aq) + CaCO3 (s) → Ca(HCO3)2 (aq)The Calcium Hydrogencarbonate is easily decomposed on heating. The calcium carbonate produced is insoluble and is precipitated out.Ca(HCO3)2 (aq) → CaCO3 (s) + CO2 (g) + H2O (l)As calcium ions are removed, the hard water is softened. Calcium Carbonate is deposited on the heating vessel. Permanent Hard WaterCannot be softened by boilingCarbonates are not the only calcium or magnesium containing compounds found in rocks, gypsum, for example contains calcium sulphate.When rain passes over these rocks, calcium and magnesium ions can dissolve in the water and make it hard. These compounds do not decompose on heating, the ions stay in the water and it remains hard.CaSO4 (s) + aq → Ca2+ (aq) + SO42- (aq)Softening Hard WaterBoiling can be used but only for temporary hard water.Adding washing soda, hydrated sodium carbonate Na2CO3.10H2O, precipitates out the calcium as its carbonate.Na2CO3 (aq) + Ca(HCO3)2 (aq) → 2NaHCO3 (aq) + CaCO3 (s)Using an Ion Exchanger that removes the calcium or magnesium ions and replaces them with other suitable ions. Advantages of Hard WaterCalcium is needed for strong bones and teeth and may help to prevent heart disease. You would, however, have to drink a large amount.Hard water is supposed to taste better but this is presumably a matter of taste. It is better for making beer also. Less likely to dissolve heavy metals such as lead. So if the hard water is flowing through old lead pipes then there is smaller possibility of lead dissolving in the water and damaging your health.In tanning leather the calcium or magnesium ions make the leather cure better.Disadvantages of Hard WaterHard water will, of course, produce lather with soap eventually but the amount of soap required makes it much more expensive.When temporary hard water is heated in a kettle the calcium carbonate builds up on the heating element. This is known as fur.When the hot water is in boilers and popes the deposits are known as scale or limescale. Pipes can become blocked and the hot water system is much less efficient.Characteristics of a Hard Water AreaHard water comes from areas with chalk or limestone. As the rain, containing the carbonic acid runs through these rocks some of the calcium carbonate is removed as the soluble calcium hydrogencarbonate.Over many centuries this can create caves, stalagmites and stalactites. A drop of temporary hard water can lose water by evaporation and as a result the calcium hydrogencarbonate decomposes leaving a solid deposit of calcium carbonate.Treatment of WaterThe treatment of water can involve a variety of processes, depending on the origin of the water, but there are two main treatments.Filtering: The water is allowed to run through sand beds to remove insoluble solid matter. There may be two different sand beds: first course to remove larger solid and after fine sand to remove smaller particles.Chlorination: Microbes in water cause several diseases e.g. cholera. Chlorine is added to water in order to kill bacteria. Great care is needed in order to use enough chlorine to kill bacteria but not harm humans or animals. PollutionA pollutant is a chemical in a situation where it is likely to kill or harm. There are many ways in which water can be polluted.Fertilisers: Used to get a better crop yield; they contain the nitrates and phosphates required for healthy growth for plants. If too much is used, it can run off the field and into the water system.Detergents: Containing phosphates as brighteners also contribute to water pollution.14. Acids & BasesAcids: Acids contain hydrogen and when they dissolve in water they produce hydrogen ions. Acids react to form salts and the acid determines the salt.Bases: A base reacts with an acid to form a salt and water. Metal oxides and hydroxides are bases. Alkalis are soluble bases. When an alkali dissolves in water it produces hydroxide ions.Neutralisation: When an acid and an alkali react the hydrogen and hydroxide ions form water. Water is neutral and so this type of reaction is called neutralisationAcid reacts with metal- metal + acid → salt + hydrogenAcid reacts with carbonates- acid + carbonate → salt + CO2 + H2OFurther ClassificationOxides-Metal oxides are basic and non-metal oxides are acidic. Metal Oxide and Non-Metal Oxide-Acid + Base → Salt + Water15. ElectrolysisElectrolysis- the decomposition of a liquid electrolyte by a direct current of electricity.Electrodes- graphite rods are placed in the liquid and connect to a supply of electricity. The positive pole is the anode and cathode is the negative pole.The negative cathode attracts positive ions, cations. The positive anode is attracts negative ions, anions.Molten ElectrolysisElectrolyteCathode ProductAnode ProductLead BromideLeadBromine341757011430Cathode- Pb2+ (l) + 2e- → Pb (s)Anode- 2Br- (l) → Br2 (g) + 2eOverall- PbBr2 (l) → Pb (l) + Br2 (g) Lithium ChlorideLithiumChlorine34175707619Cathode- Li+ (l) + e- → Li (l)Anode- 2Cl- (l) → Cl2 (g) + 2e-Overall- 2LiCl (l) → 2Li (l) + Cl2 (g)Electrolysis in Aqueous SolutionsElectrolyteCathode ProductAnode ProductLead BromideLeadBromineCathode- 2H+ (aq) + 2e- → H2 (g)Anode- 4OH- (aq) → 2H2O (l) + O2 (g)Overall- H2O (l) → H+ (aq) + OH- (aq)Electrolysis in IndustryExtraction of Aluminium297180099695Cathode- Al3+ + 3e- → AlAnode- 2O2- → O2 + 4e- Oxygen reacts with carbon at this temperature forming Carbon Dioxide.C + O2 → CO2Refining of CopperCathode- Cu2+ (aq) + 2e- → Cu (s)3248025189865Anode- Cu (s) → Cu2+ (aq) + 2e-The copper ions in the electrolyte move to the cathode. They gain elections forming copper atoms that are deposited on the pure copper cathode. As a result the cathode increases in size. At the anode the copper atoms lose electrons and become ions. The ions leave the anode and enter the electrolyte. The anode gets smaller.Electrolysis of Brine (the chlor-alkali process)Brine is used to produced Chlorine, Hydrogen and Sodium HydroxideThe Chloride ions are discharged at the anode- 2Cl- → Cl2 + 2e-The hydrogen ions are discharged as the cathode- 2H+ + 2e- → H2 The remaining ions are Na+ and OH-, they form sodium hydroxide.The products are of this process are very useful-ChlorineSodium Hydroxide2800350346075-352425260985Hydrogen16. EnergeticsEnergy Changes in ReactionsExothermic reactions:In an exothermic reaction, heat energy is given out. Heat energy given outcenter86360An energy level diagram to show an exothermic reaction.This is because the products are lower in energy than the reactants, so the excess energy from the reactants are given out as heat energy.Examples: combustion reactions metals with an acid neutralisation (metals in water)Endothermic reactions:In an endothermic reaction, heat energy is taken in.center-1270An energy level diagram to show Heat energy taken inan endothermicreaction.This is because the products are higher in energy than the reactants, so the extra energy needs to be taken from the surroundings.Examples: thermal decomposition of metal carbonates (products CO2 + metal oxide) Experiments to Measure Energy Changes1. Reactions involving solidse.g. For neutralisation reactions, displacement reactions, dissolving, metal and acid etc.Polystyrene cup Reaction mixtureThermometerThe change in temperature of the reaction is measured. Heat energy given out / taken in (J) = mass (g) x specific heat x temperature change (c) (2)(3)(1) of solutions – for most solutions mass = volume ( mass = density x volume – density of water = 1gcm3)(2) 4.18 Jg-1C-1(3) no (-xoC) just temperature change2. Combustion reactionse.g. Burning on alcoholThe alcohol is burnt in a spirit burner, and heat produces is used to heat up a container of water.-28575109855Conical flaskClampThermometerKnown volume of waterSpirit burnerAlcoholThe alcohol is allowed to burn for a given time. The mass of alcohol is recorded before and after burning, so that the mass of alcohol burnt is known. The change in temperature of the water is measured. Heat energy given out / taken in (J) = mass (g) x specific heat x temperature change (c) (2)(3)(1) of solutions – for most solutions mass = volume ( mass = density x volume – density of water = 1gcm3)(2) 4.18 Jg-1C-1(3) no (-xoC) just temperature changeEnthalpy change‘The amount of heat energy given out or taken in per mole of reagent during a reaction = ΔH’Δ means ‘change in’H means ‘energy’ΔH is negative for exothermic reactions (the reactants are losing energy)- ΔHΔH is positive for endothermic reactions + ΔH(the reactants are gaining energy)1. Heat energy (kJ) = (mass (g) x specific heat x temperature change (oC)) ÷ 10002. Work out per mole3. Give sign (+ ΔH or – ΔH)Why do reactions give in or take in energy?Break bonds --> energy taken in (endothermic).New bonds formed --> exothermicIf more energy needed to break bonds than given out making more bonds – reaction is endothermic.If less energy needed to break bonds than given out making more bonds – reaction is exothermic.Calculating bond energiesBond energy (KJ mol-1) = the amount of energy needed to break a particular bondThe stronger the bond, more energy needed to break it, the higher the bond energy.Method:center603885E.g. Methane and chlorineCH4 + Cl2 --> CH3Cl + HClBonds that are broken: 4 x H – C 1 x Cl – Cl Bonds that are made: 3 x C – H 1 X C – Cl 1 X H – ClBond energies: C – H = +413 kJ mol-1Cl – Cl = + 243 kJ mol-1C – Cl = + 346 kJ mol-1H – Cl = + 432 kJ mol-1Bonds that are broken:4 x H – C = 4 x +413 = +1652 kJ mol-11 x Cl – Cl= 1 X 243= +243 kJ mol-1Total energy taken in = +1895 kJ mol-1Bonds that are made: 3 x C – H = 3 x -413 = -1239 kJ mol-11 x C – Cl= 1 x -346= -346 kJ mol-11 X H – Cl = 1 x -432= -432 kJ mol-1Total energy given out = -2017 kJ mol-1Add together the values for total energy taken in and total energy given out to find the overall energy change:Overall energy change ΔH = +1895 – 2017 = -122 kJ mol-1-81915430530Because ΔH is negative, we can see that the reaction is exothermic. 17. Reactivity SeriesPotassium- PoorSodium- Scientists Calcium- CanMagnesium- MakeAluminium- AZinc- ZooIron- InCopper- Coleraine-675005-56769018. Reaction RatesRate= Change in Mass or Volume of Product given offTime TakenCollision TheoryChemical reactions occur when particles of reactant collide with enough energy to react. This minimum energy is called the?Activation Energy.Smaller object react faster because there is a greater surface ?are to volume area ratio, therefore there are more collisions, and more frequently.The rate of reaction decreases as the concentration of reactant becomes less, and more products are made.As the temperature increases, the rate of reaction increases as the particles have more kinetic energy, therefore they collide more frequently. More particles achieve activation energy.Factors Affecting Rates of ReactionTemperatureIncreasing the temperature of a reaction SPEEDS it up (INCREASES the rate of reaction)The particles have more kinetic energy so they move about more and collisions occur more frequently.As there are more collisions, there are more successful collisions so the rate of reaction increases.ConcentrationIncreasing the concentration of reactant liquids in a reaction also increase the rate of reaction.A high concentration means more particles per cm3 so there are more collisions per second which means there are more successful collisions so the reaction speeds up.Surface AreaIncreasing the surface area of a reactant solid increases the rate of reactions.A powdered substance always has a larger surface area than a block substance weighing the same amount.The more finely divided the solid is, the more of it is exposed to react with the other particles.Use of a CatalystUse of a catalyst increases the rate of reactionA catalyst is a substance that speeds up a reaction but is chemically unchanged. When the reaction finishes you have the same mass of catalyst. A catalyst provides an alternative route for the reaction, one with lower activation energy.19. Periodic TableThe periodic table was developed to classify elements before atomic structure was understood.It is a powerful aid to understanding the properties and reactions of the elements.Early Attempts to Classify the Periodic TableNewlands, and then Mendeleev, attempted to classify the elements by arranging them in order of their atomic weights. The list can be arranged in a table so that elements with similar properties are in columns, known as Groups. The table is called a periodic table because similar properties occur at regular intervals.The early periodic tables were incomplete and some elements were placed in inappropriate Groups if the strict order of atomic weights was followed.Mendeleev overcame some of the problems by leaving gaps for elements that he thought had not been discovered.When electrons, protons and neutrons were discovered early in the 20th century, the periodic table was arranged in order of atomic (proton) numbers. When this was done, all elements were placed in appropriate groups.The Modern Periodic TableThe modern periodic table can be seen as an arrangement of the elements in terms of their electronic structures.Elements in the same Group have the same number of electrons in their highest occupied energy level (outer shell).The trends in reactivity within Groups in the periodic table can be explained because the higher the energy level:the more easily electrons are lostthe less easily electrons are gained.Group 1- Alkali MetalsThe elements in Group 1 of the periodic table (known as the alkali metals):are metals with low density (the first three elements in the Group are less dense than water)react with non-metals to form ionic compounds in which the metal ion carries a charge of +1. The compounds are white solids which dissolve in water to form colourless solutionsreact with water releasing hydrogenform hydroxides which dissolve in water to give alkaline solutions.In Group 1, the further down the group an element is:the more reactive the elementthe lower its melting point and boiling point.Group 7- HalogensThe elements in Group 7 of the periodic table (known as halogens):have coloured vapoursconsist of molecules which are made up of pairs of atomsform ionic salts with metals in which the chloride, bromide or iodide ion (halide ion) carries a charge of –1form molecular compounds with other non-metallic elements.In Group 7, the further down the group an element is:the less reactive the elementthe higher its melting point and boiling point.A more reactive halogen can displace a less reactive halogen from an aqueous solution of its salt.Example: Potassium Iodide + Chlorine = Potassium Chloride + IodineTransition MetalsIn the periodic table between Groups 2 and 3 is a block of elements known as the transition elements. These elements are all metals.The transition elements have similar properties and some special properties because a lower energy level (inner shell) is being filled in the atoms of the elements between Groups 2 and 3. This is because the third energy level can hold up to 18 electrons, once two electrons have occupied the fourth pared with the elements in Group 1, transition elements:have higher melting points (except for mercury) and higher densitiesare stronger and harderare much less reactive and so do not react as vigorously withWater or oxygen.Many transition elements have ions with different charges; form coloured compounds and are useful as catalysts.-476885-400050-476250-400050-133350-36195020. Chemical CalculationsRelative Atomic MassRAM= Actual mass of Atom12 of carbon-12Relative Formula MassCan be found by adding together all the atomic masses of all the atoms in the formula of the element or compound.Br2= (RAM Br) x 2NaCl= RAM Na + RAM Cl Moles and Number of ParticlesOne mole of any element or compound contains the same number of particles, which is 6 x 1023. The number of moles is found by dividing the number of particles by 6 x 1023.moles= number of particles6 x 1023Moles and MassOne mole of any element or compound weighs it RAM or RFM in grams and so the number of moles in a sample can be found.moles= mass (g)RAM or RFMChemical reactions can be represented by balanced chemical equations. Balanced chemical equations do much more than tell us what reacts and what is formed. The big numbers that you see in front of some formulae are called stoichiometric coefficients. Mg + 2HCl MgCl2 + H2Stochiometric coefficients tell us the ratio of moles that react. In the example above, they tell us how much magnesium is needed to react completely with hydrochloric acid.When we read out the balanced equation above, we don’t just say ‘magnesium plus hydrochloric acid goes to magnesium chloride plus hydrogen’. Instead, we should actually say ‘one mole of magnesium plus two moles of hydrochloric acid goes to one mole of magnesium chloride plus one mole of hydrogen’.massmolesRMMCalculating Reacting MassesThere are three steps to these calculations:Work out the number of moles of reactant (moles = mass / RAM).Use the balanced chemical equation to work out the number of moles of product.Work out the mass of product using mass = moles x RMM.Example OneCalculate the mass of magnesium chloride formed when 20g of magnesium reacts with hydrochloric acid: Mg + 2HCl MgCl2 + H2moles of Mg= mass / RAM= 20 / 24= 0.833 molmoles of MgCl2= 0.833 mol because the balanced chemical equation shows a 1:1 ratiomass of MgCl2 = 0.833 x (24 + 71)= 79.2gIf you need to calculate the mass of reacant needed to make a given quantity of product, the method is almost identical:Example TwoCalculate the mass of calcium carbonate needed to generate 11g of carbon dioxide according to the following balanced chemical equation: CaCO3 + H2SO4 CaSO4 + H2O + CO2moles of CO2= mass / RAM= 11 / (12 + 32)= 0.25 molmoles of CaCO3= 0.25 mol because the balanced chemical equation shows a 1:1 ratiomass of CaCO3= 0.25 x (40 + 12 + 48)= 25gSometimes the question mentions that one of the reactants is in excess. For example, question 1 below says that “7.3g of hydrogen chloride reacts with excess ammonium hydroxide “. This just means that all 7.3g of hydrogen chloride reacts and none is left over. 1) Calculate the mass of ammonium chloride, NH4Cl, formed when 7.3g of hydrogen chloride reacts with excess ammonium hydroxide: NH4OH + HCl NH4Cl + H2O2) Calcium carbide, CaC2, reacts with water to form acetylene, C2H2 :CaC2 + 2H2O C2H2 + Ca(OH)2Calculate the mass of acetylene formed when 80g of calcium carbide reacts with excess water.3) Calculate the mass of sodium oxide, Na2O, formed when 1.2g of oxygen gas reacts with excess sodium:4Na + O2 2Na2O4) What mass of iron is formed when one kilogram (1 000 g) of iron ore, Fe2O3, reacts with excess carbon monoxide? Fe2O3 + 3CO 2Fe + 3CO25) Calculate the mass of nitric acid required to react completely with 90g of copper:3Cu + 8HNO3 3Cu(NO3)2 + 2NO + 4H2O6) A student needs to prepare 80g of magnesium oxide, MgO, by combustion of magnesium metal in oxygen:Mg + H2O MgO + H2What mass of magnesium is required?7) What mass of copper oxide needs to be reduced to obtain 8g of copper?CuO + H2 Cu + H2O8) Calculate the mass of sodium hydroxide required to precipitate out 36g of iron(II) hydroxide: FeSO4 + 2NaOH Fe(OH)2 + Na2SO49) What mass of water is required to react with aluminium carbide, Al4C3, in order to form 9.6g of methane gas? Al4C3 + 12H2O 4Al(OH)3 + 3CH410) Calculate the mass of phosphoric acid required to generate 30g of hydrogen gas: 6Li + 2H3PO4 2Li3PO4 + 3H2Answers1. 10.7g2. 32.5g3. 4.65g4. 700g5. 236.25g6. 48g7. 10g8. 32g9. 43.2g10. 196g21. Metals and their CompoundsProperties of MetalsHigh melting and boiling pointsMost are hard- not easily dented or scratchedMost are strong- easily support a loadMost are denser than waterHigh Lustre- ShinyGood Electrical ConductorsGood Thermal ConductorsMetals are ductile- drawn into wiresMetals are malleable- beaten into shapeReaction of Metals with Non- MetalsReaction with Cold Water-Only calcium, potassium and sodium react immediately with cold water. The metal will move rapidly over the surface and a noise will be heard as hydrogen evolved burns. Potassium will have a lilac flame and sodium a yellow one. A metal hydroxide is produced and it dissolves in the water to create an alkaline solution.metal+cold water →metal hydroxide+hydrogenReaction with SteamIron, Magnesium and zinc will react when heated with steam. The products are the metal oxide and hydrogen. metal+steam →metal oxide+hydrogenReaction with dilute acidCopper, iron, magnesium and zinc can be placed in dilute acid usually hydrochloric acid.All but copper will react producing metal salt and giving off hydrogen. As before, magnesium is the most reactive, then zinc and iron is the least reactive. Calcium, potassium and sodium have vigorous reactions.metal+acid →metal salt+hydrogenDisplacement ReactionsA more reactive metal will displace a less reactive metal from a solution of its salt. Extraction of IronYou will mainly see iron in the form of its alloy – steel. Iron is found as an ore in its oxides – haematite Fe2O3 or magnetite Fe3O4. Iron is extracted from its ore by reduction with carbon; this is because carbon is relatively cheap.The blast furnaceIron is extracted in a blast furnace, this is a continuous reaction, and the furnaces are only ever turned off after a few years to replace the lining. Coke, iron ore and limestone are fed into the top of the furnace and hot blasts of air at the bottom keep the furnace at around 1500 degrees Celsius.Coke is a cheap form of carbon which is created by heating carbon in the absence of air. This reacts with oxygen and more coke to produce carbon monoxide which acts as the reducing agent.ReactionsFirst, the coke reacts with oxygen to produce carbon dioxide:C (s) + O2 9g) → CO2 (g)Then the carbon dioxide further reacts with coke to produce carbon monoxide:CO2 (g) + C (s) → 2COThis carbon monoxide then acts as a reducing agent and reduces the haematite to carbon dioxide and iron:Fe2O3 (s) + 3CO (g) → 2Fe (l) + 3CO2 (g)The iron then forms a liquid from the high temperatures in the blast furnace. It trickles to the bottom where it is tapped off.Limestone is broken down in the blast furnace:CaCO3 (s) → CaO (s) + CO2 (g) Because calcium oxide is a base, it reacts with silica which is an acid:CaO (s) + SiO2 (s) → CaSiO3 (l)The molten carbon silicate floats on top of the molten iron and it’s known as slag, this is tapped off and used in building rods. 2762250174625-371475174625-161925600075CarbonatesUse of Metals Magnesium is combined with other metals to form a light weight alloy which is used on air plane bodies.Aluminum is used to make overhead cables. It can also be used to make saucepans because of a layer of oxide which forms over it.Zinc is used to cover iron and prevent it from rusting. Zinc is alloyed with copper to form brass. Iron, as steel, has many uses. It is used in the construction of ships, bridges, tools, car bodies and cookers. It is strong and cheap. Iron is essential in our diet because it is needed in the formation of hemoglobin.Copper is a good conductor of electricity and does not react with water even when hot so it is used to make water pipes. Also used to make alloys for coins. Calcium is needed in our diet to help make strong bones and teeth.22. Non-Metals and their CompoundsHydrogenPhysical PropertiesIt is colourless and odourless, insoluble in water and less dense that air.Chemical PropertiesA Sample of hydrogen burns explosivelyBurns with a clean blue flame producing water vapour that may condense on glass2H2 + O2 → 2H2OHydrogen has reacts with heated copper (ll) oxideBlack copper oxide changes to pink, condensation appearsCuO + H2 → Cu + H2OHydrogen reacts with nitrogen forming ammonia in the Haber-Bosch processN2 + 3H2 → 2NH3Preparation of HydrogenHydrogen is prepared using zinc (or magnesium) and dilute hydrochloric acidHydrogen is collected over water as it is insoluble in water.The reaction with magnesium is more vigorous and not recommended for a controlled preparation of hydrogen gas.Zn + 2HCL → ZnCl2 + H2Test for HydrogenApply a lighted splint to the gas.Uses of HydrogenWeather BalloonsRocket EnginesClean FuelCarbonCarbon exists as two distinct isotopes, Graphite and Diamond. The two forms have identical atoms but it is the way in which atoms are bonded that makes the forms different.Diamond-Hardest naturally occurring substanceVery high melting point (3500c)Diamond-tipped tools are used for cutting glass/drilling/engravingEach carbon atom is strongly bonded to four others in a tetrahedral arrangementThe strength and number of bonds accounts for very high melting pointDoes not conduct electricity42291002084705Graphite-Only non-metal to conduct electricityVery high melting point (3600c)Layered structure that means layers can slide over each otherEach carbon atom is strongly bonded to three others in a hexagonHas delocalised electrons between the layersStrong covalent bonds within layers give it a high melting pointBuckminsterfullerene (C60)-Covalently bonded ball consisting of hexagons and pentagonsSoluble in organic solvents like tolueneChemical Properties of CarbonCarbon burns in an excess of oxygen. It burns with a dirty orange flame, forming a colourless and odourless gas.C + O2 → CO2Carbon monoxide is formed in a limited supply of oxygen.2C + O2 → 2COChemical Properties of Carbon DioxideReaction of Carbon Dioxide with WaterCarbon reacts with water to form the weak acid carbonic acid, H2CO3This is used in fizzy drinksReaction of Carbon Dioxide with burning magnesiumA piece of burning magnesium in a gas jar of carbon dioxideA bright white light; a white solid is produced which is magnesium oxide and specks of black carbon2Mg + CO2 → 2MgO + CTest for Carbon DioxideCarbon Dioxide is bubbled through limewater and it turns milky white.Use of Carbon DioxideCarbon Dioxide is used in:Fire Extinguishers Carbonated DrinksDry IceNitrogen (N2)Nitrogen is a colourless, odourless gas that is insoluble in water. It is a diatomic gas which means it consists of two atoms of the same element.Properties of Nitrogen (N2)Nitrogen and hydrogen react to form ammonia, the Haber-Bosch process.Nitrogen and hydrogen are mixed 3:1They are reacted at 450c, a pressure of 200 atm and with an iron catalyst.N2 + 3H2 → 2NH3The gases are then cooled to condense the ammonia.Unreacted nitrogen and hydrogen are recycled.The Haber-Bosch process cannot be demonstrated in the laboratory due to the high pressure and temperature used, the specialised plan required and safety of staff and students. It is also too expensive.Uses of NitrogenNitrogen is used:As a coolant (liquid nitrogen)In food packaging (nitrogen creates an inert atmosphere used to keep food fresh)Nitric AcidNitric acid is manufactured from ammonia. There are three main stages of production.Nitric Acid ManufactureStage 1: Catalytic oxidation of ammonia Ammonia and air are mixed and pass over platinum gauze at a temperature of 950c and at a pressure of 2 atmospheres.The product is nitrogen monoxide, NOEquation: 4NH3 + 5O2 → 4NO + 6H2OStage 2: Further oxidation of nitrogen monoxideThe gases are mixed with more air and nitrogen monoxide is converted to nitrogen dioxide.Equation: 2NO + O2 → 2NO2Stage 2: Formation of Nitric AcidThe gases are mixed with more air and passed up a tower of glass beads that have water flowing down.Equation: 4NO2 + O2 + 2H2O → 2HNO3OxygenOxygen is a colourless, odourless gas that is only slightly soluble in water and is slightly denser that air.Test for OxygenA glowing splint is put into oxygen and it relights. Uses of OxygenOxygen is used in:MedicineWeldingRocket EnginesProperties of Oxygen(See revision book pg 136-137)SulphurSulphur is a brittle yellow solidSulphur does not react with water or acid but burns with a blue flame in air/oxygen producing the colourless but pungent gas sulphur dioxide, SO2.Uses of SulphurSulphur is used in:Vulcanising of RubberFungicideProperties of Sulphur DioxideSulphur Dioxide reacts with water to form the weak acid sulphurous acid.SO2 + H2O → H2SO3Sulphur dioxide in the atmosphere reacts with rain water to form acid rain.Acid Rain has three main effects-Corrodes limestoneDefoliates treesPollutes lakes and riversAcid Rain can be prevented by-Removing sulphur from fuel sourcesUsing renewable energyUsing cars fitted with catalytic convertersBurning less fossil fuelsProperties of Dilute Sulphuric AcidReaction of concentrated sulphuric acid with sodium chloride.Bubbles of gas; fumes; heat releasedNaCl + H2SO4 → NaHSO4 + HClThis reaction is used to prepare hydrogen chloride gas in the laboratory. It is the first and only reaction where you will meet the hydrogen sulphate ion.Reaction of concentrated sulphuric acid with sugar.Concentrated sulphuric acid dehydrates sugar to form carbon which is a black solid and water which is released as water vapour.The sugar swells and rises in the container. The reaction is not immediate. Heat is released and there is a distinct caramel smell and a pungent odour. A black solid remains.Sugar → Carbon + WaterReaction of Concentrated sulphuric acid with hydrated copper (ll) sulphate.The blue solid changes to white. The concentrated sulphuric acid again behaves as a dehydrating agent, removing the water of crystallisation to form the white solid anhydrous copper (ll) sulphate.Reaction of concentrated sulphuric acid with alcohols and organic acids forming esters.The formation of the ester ethyl Ethanoate is promoted using concentrated sulphuric acid, again as a dehydrating again. Concentrated sulphuric acid acts most often as a dehydrating agent removing water.Hydrochloric AcidHydrochloric acid is a typical mineral acid and undergoes typical reactions with metals, metal oxides, metal hydroxides and metal carbonates. Almost all chlorides are soluble in water and so the salts produced are in solution.A metal ion in a compound that will not dissolve in water can be made to dissolve by reaction with a dilute acid, such as hydrochloric acid or nitric acid. Properties of Hydrochloric AcidReaction of hydrochloric acid with metals.Most metals react with dilute hydrochloric acid to give the corresponding chloride and hydrogen gas.Bubbles of gas produced; heat released; metal disappears; colourless solution formedMg + 2HCl → MgCl2 + H2Reaction of hydrochloric acid with metal oxides and hydroxides Metal oxides and hydroxides react with dilute hydrochloric acid, producing the corresponding chloride and water.Solid disappears; heat released; the colour of the solution formed depends on the metal ions present, for example a solution of copper chloride is blue but most are colourless solutions.CaO + 2HCl → CaCl2 + H2OReactions of Hydrochloric acid with Metal carbonates. All metal carbonates react with dilute hydrochloric acid, producing the corresponding chloride, carbon dioxide and water. Solid disappears; bubbles of gas produced; heat released; the colour of the solution formed depends on the metal ion.CaCO3 + 2HCl → CaCl2 + CO2 + H2O23. Organic ChemistryOrigin of OilCrude oil?is?formed?from organic material of the remains of plant and animal organisms that lived millions of years ago.? These remains form sediments e.g. at the bottom of seas, and?become?buried?under layers of sedimentary rock. They?decay,?without air (oxygen), under the action of?heat and pressure?to form crude oil over millions of years.It is a?non-renewable?and?finite (limited reserves) energy resource because it takes millions of years to form and we burn it faster than it has is formed! Coal,?peat?and?natural gas?are the other principal?non-renewable fossil fuels?formed from the remains of plants or animals.Fractional Distillation of OilFractional Distillation is carried out in a fractioning column.The crude oil enters at the bottom as a hot, gaseous mixture.The fractioning column has bubble caps that allow gases to move upwards. The temperature decreases up the column.As the gases move up the column, hydrocarbons condense when the temperature of the column is the same as their boiling point.See Table on next page for Fractioning of Oil-208398110322Combustion of HydrocarbonsCombustion: is the reaction of a fuel with oxygen, producing oxides and releasing plete Combustion: is a fuel burning in a plentiful supply of oxygen/air, producing carbon dioxide and water and releasing heat.Incomplete Combustion: is a fuel burning in a limited supply of oxygen/air and producing carbon monoxide and water and releasing heat.Homologous SeriesA homologous series is a family of organic molecules that have the same general formula; show similar chemical properties and show a graduation in their physical properties and differ by a CH2 unit.There are two hydrocarbon homologous series, called the alkanes and alkenes. Alkanes are unreactive hydrocarbons and Alkenes are more reactive hydrocarbons.Saturation and UnsaturationAlkenes have on C=C double bond per molecule – they are unsaturated. Alkanes have no C=C double bond per molecule- they are saturated.Testing for double bonds/saturationAdd the substance to bromine water. For an unsaturated substance/any alkene: colour changes from a red-brown to colourlessFor a saturated substance/any alkane: colour remains red-brownAlkenes and AlkanesFigure SEQ Figure \* ARABIC 5: The first four AlkanesFigure SEQ Figure \* ARABIC 6: The first two AlkenesAddition PolymerisationPolymerisation is the process of creating a long molecule from a small molecule which forms the repeating unit in the polymer.A polymer is a long molecule formed by bonding together small molecules into a chain.Addition polymerisation is the process of adding molecules together to form a polymer. The long molecule is called the polymer.The simple molecule from which a polymer is formed is called the monomer.The monomer has a double bond between the two carbon atoms.The monomer is an alkene.The polymer is shown as the monomer with only a single bond in a square bracket. n molecules of monomer must be at the beginning of the equation.The polymer structure has n after it to show that the polymer repeats n mon Addition Polymers352425073025Polythene-Uses: plastic bags and bottles3667125133350Poly Vinyl Chloride-Uses: vinyl records, door and window frames, clothingDisposal of PolymersThere are two methods of disposal for polymers-LandfillIncinerationThere are environmental problems associated with each method of disposal-Landfill wastes landIncineration produces polluting gases which are released into the atmospherePolymers are increasingly being recycled and biodegradable polymers have been developed and are now in use. Reactions of EtheneCombustion of Ethene-Ethene burns with an orange flame, releasing heat.C2H4 + 3O2 → 2CO2 + 2H2OEthene reacts with steam, producing ethanol-C2H4 + H2O → C2H5OHEthanol?C2H5OHReactions of EthanolCombustion of Ethanol-Burns with a clean blue flame, heat is released.C2H5OH (l) + 3O2 (g) → 2CO2 (g) + 3H2O (g)Making EthanolEthanol can be produced by the fermentation of sugars. Sugar solution is mixed with yeast in warm conditions in the absence of oxygen. The reaction produces carbon dioxide and ethanol.Sugar → ethanol + carbon dioxideEthanol can be made by reacting ethene with steam.C2H4 + H2O → C2H5OHUse of EthanolEthanol is used for-In alcoholic drinksAs a solventEthanoic AcidCH3COOHEthanoic acid is also called acetic acid. A dilute solution of Ethanoic acid is vinegar.Reactions of Ethanoic AcidReaction of Ethanoic acid with a metalBubbles of has produced, heat released, metal disappears, colourless solution formed.Ethanoic Acid + metal → Metal Ethanoate + hydrogen2CH3COOH + Mg → (CH3COO)2Mg + H2Reaction of Ethanoic acid with a metal oxideHeat released, solid disappears, colourless solution formedEthanoic Acid + Metal Oxide → Metal Ethanoate + Water2CH3COOH + CaO → (CH3COO)2Ca + H2OUses of Ethanoic AcidEthanoic Acid is used as:A preservativeFlavouring EsterificationAn ester is a compound formed between a carboxylic acid and an alcohol.CH3COOH + C2H5OH → CH3COOC2H5 + H2OEthanoic Acid + Ethanol → Ethyl Ethanoate + WaterEthyl EthanoateCH3COOC2H5Uses of Ethyl EthanoateEthyl Ethanoate is used as:Flavouring in FoodsSolventPreparation of Ethyl EthanoateMix equal amounts of Ethanoic acid and ethanol in a boiling tube. Then add a few drops of concentrated sulphuric acid and warm gently.Preparation of Organic CompoundsThe first four alkanes are colourless gases.The first two alkenes are colourless gases.All the polymers are white solids. Coloured dyes can be added to them to make coloured plastics. Ethanol is a colourless liquid with an alcohol like odour.Ethanoic acid is a colourless liquid with vinegar like odour.Ethanol and Ethanoic acid mix with water.Ethyl Ethanoate is a colourless liquid with a fruity/solvent smell.Ethyl Ethanoate does not mix with water.The high the carbon content, the sootier and more orange it’s flame when it burns.The lower the carbon content, the less sooty and more clean and blue its flame when it burns.Ethanol burns with a cleaner, blue flame than the alkanes or alkenes.THIS SECTION AND PROPERTIES MUST BE KNOWN FOR QUESTIONS INVOLVING UNKNOWN ORGANIC COMPOUNDS. A SAMPLE OF PROPERTIES WILL BE GIVEN AND THE COMPOUND MUST BE WORKED OUT USING THE COMPOUNDS.24. Human InfluencesPollutionThe effect of human activity can result in chemical being found where they cause harm, such chemicals are called pollutants.As more has been learned about pollution, efforts have been made to deal with problems.Once sewage went straight into the local river or sea, but now it is dealt with by sewage works.The Clean Air Act that allowed local authorities to set up smokeless zones has greatly reduced air pollution.Oceans, seas and rivers that are polluted in one country affect many others. A factory in Basle, Switzerland had a fire, when it was being out pollutants were washed into the river Rhine. The pollution was carried down the river causing problems as it passed through France, Germany, and The Netherlands.The air is international and acid rain is an international problem. The sulphur dioxide may be produced in one country and carried away by the wind. Lakes in Scandinavia have been badly affected by acid rain formed in Britain.Greenhouse gases are also another matter for international concern. Governments meet at summits to discuss the environment and the harm we are causing it. Unfortunately getting them all to agree about what has to be done seems to be impossible.25. Industrial ProcessesLimestone QuarryingLimestone has many uses and is a very important raw material for industry. Limestone in an abundant raw material and as it is relatively easily obtained it is fairly cheap. The business of quarrying provides jobs at the quarry and transportation.Unfortunately, quarries destroy natural habitats and the traffic associated with them contributes to noise and dust pollution, as does blasting.247650566420If a new quarry is to be dug consideration must be given to the balance between the demands and care for the environment. Peat CuttingPeat has been used as a fuel for centuries. In Ireland families has rights to remove the turf from certain, usually quite small, strip of local peat bogs.Once industry became involved, the removal of peat from the bog speeded up and is now used as a fuel and for treating soil and making gardening composts.Peat bogs are very special habitats and many of the plants found in them are not found anywhere else. Large-scale peat cutting was destroying these habitats too rapidly. Concern about the loss of peat bogs prompted many gardeners to stop using peat-bases products.Lignite MiningLignite, a brown soft coal, can be found around Lough Neagh. The Crumlin area was estimated to have reserves of about 200 million tonnes that could be obtained by open cast mining. During the energy crisis of the 60’s interest was shown in these reserves. Three possibly commercial seams were identified and they could have been very important for Northern Ireland. It was suggested that the lignite could be extracted and burned to provide 40 per cent of the electricity needs for the country.This would have been of economic value, as we would have needed to import less oil. The project in opening and running the mine would have provided employment; the forecast was for about 400 new jobs. The lignite found in Northern Ireland is low in sulphur and would result in relatively low atmospheric pollution when it was burnt.There were many factors against the project. Not only would the mining destroy the natural habitat of local wildlife, it could also be unsightly. The area has a thriving fishing industry and productive agriculture land.It included five listed buildings and thought it would interrupt water supplies. In the end it was shelved but who knows what may happen in the future. Solution MiningCommon salt, sodium chloride, is a very important raw material for the chemical industry. Most of our salt comes from Cheshire, England and is brought to the surface by solution mining.Water is pumped down into the rock and the salt dissolves leaving behind the rock. The salt solution, brine, is pumped to the surface.This method has a much less detrimental effect on the environment than other forms of mining.971550573405Unfortunately, solution mining weakens the rock and can result in subsidence. 26. RadioactivityAlphaBetaGammaSymbolContains2 protons and 2 neutrons1 electron – from the nucleusAn electromagnetic waveEmitted when4 particles are emitted from the nucleus (this is the same as a helium nucleus)A neutron changes into a proton and emits a very fast electronThe nucleus vibrates (in an electric and magnetic field)Relative charge+2-10Ionising abilityhighmediumLowRelative mass41/2000 (very low)0Stopped bypaper0.5cm AluminiumA few cm of lead or a few metres of concrete.(they exist with a range of energies so a few may be stopped by Aluminium etc)Effect in electric fieldBend towards – plate (opposites attract)Bend towards + plate (opposites attract)Go straight through (as they are uncharged)Range in air4cmA few metresInfinite (are not stopped by air)Effect in magnetic fieldChange direction in field (opposite direction to alpha)Change direction in field (opposite direction to alpha)Unaffected by magnetic field, go straight through.UsesSmoke alarms – a small source of alpha particle set up a very short distance from a detector. The alpha particles ionise the air and this makes a current that completes a circuit. If smoke particles get I the way, the circuit is broken and sets off an alarm.Not generally used.To detect thickness of Aluminium sheets on a production line. An emitter and detector are place on opposite side of the sheet. If a normal amount of gamma is detected. If the sheet is too thick then fewer gammas is detected, if the sheet is too thin then more gamma is detected and the machine is adjusted accordingly.Can be used as a tracer either in the body or in water pipes etc. A small amount of gamma source is introduced into the vessels and a gamma detector is placed over them. If a normal level of gamma is detected then the vessels are free flowing. If very high level is detected then there is a blockage or leak at that point. If little or no radiation is detected then this must be after the blockage.Carbon dating and Uranium dating – see half life.Most dangerous…When inside the body as they are highly ionising and most dangerous of the 3, but are not very dangerous outside the body as they cannot go through the skinFairly dangerous inside and outside the body as they can go through a few layers of skin and can ionise cells causing damage.Dangerous both outside and inside the body. Most dangerous of the 3 outside the body as they can penetrate through the body and ionise cell deep inside the body. Mot as dangerous as alpha or beta inside the body as it is less ionising.Half-LifeAs a radioactive isotope decays the activity of the sample decreases. The half-life of an isotope is the time taken for the activity to fall by half. Each isotope has a specific and constant half-life. Changes in the NucleusAlpha Decay: The two protons and two neutrons that make up an alpha particle leave the nucleus together as a helium ion.Beta Decay: The electron that is the beta particle is formed in the nucleus. A neutron changes into a proton, which stays in the nucleus and an electron which is emitted. Figure 7: Alpha particle emitted from Radon Figure 8: Beta Decay ................
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