Part 2: For Year 3 and 4
- 1 Section 9: The Mole Concept: Formulae and Chemical Equations
- 2 Section 10: Atomic and Molecular Structure: Chemical Bonding
- 3 Section 11: Carbon Chemistry
- 4 Section 12: Nitrogen
- 5 Section 13: Sulphur
- 6 Section 14: Chlorine
- 7 Section 15: Acids and Bases (Acidity and Alkalinity)
- 8 Section 16: Ion Chemistry
- 9 Section 17: Energy Changes in Chemical, Physical Reactions
- 10 Section 18: Reversible Reactions and Reaction Rates
- 11 Section 19: Applied Chemistry
Section 9: The Mole Concept: Formulae and Chemical Equations
Evidence for existence of atoms, molecules, ions and electrons; effect of heat and electricity on elements and compounds; Brownian Movement; diffusion experiments; qualitative relationship between diffusion rate and density. Use bromine, copper (II) sulphate crystals/water as illustrations. Effect of density on ammonia and hydrogen chloride diffusion.
Use of kinetic theory to explain nature of solids, liquids and gases. Diffusion of gases, evaporation of liquids, dissolving solute in solvent. Qualitative explanation of Boyle's and Charles' law for gases (no calculations to be set).
The mole as a basic unit. Relative atomic mass. The mole as a number of particles can be illustrated by "counting by weighing" experiments.
Determination of formulae; ionic compounds, empirical and molecular formulae. Quantitative determination of magnesium oxide and copper (II) oxide, should be carried out.
Molar gas volume; atomicity of gases; mass volume relationship for gases. Molar solutions.
Stoichiometry of chemical reactions; quantitative work must be emphasized. Reactions to be considered: (1) Ba2+ (aq) + CO
(2) Pb2+ (aq) + 2I- (aq) yields PbI2(s)
(3) Cu2+ (aq) + Fe (s) yields Cu(s) + Fe2+ (aq)
(4) CO2 evolution from Na2CO3 + HCl
(5) Titration of NaOH with HCl and H2SO4 recommended.
Use of ionic equations and full formulae equations (latter recommended) in the calculation of reacting masses.
Section 10: Atomic and Molecular Structure: Chemical Bonding
The significance of the outer electrons in chemical bonding. Qualitative treatment of the energetics of chemical bonding. Consider the molecules in terms of a position of balance between p-p, e-e repulsions, and p-e attraction (the ionic bond as an extreme example).
Significance of the noble gas configuration; covalent bond as electrons sharing; ionic bond as electron-transfer. Consideration of C-C and C=C.
Influence of bond type on physical and chemical properties (melting point, solubility and electrical conductivity). Molecular, giant atomic and giant ionic structures.
Metallic bond related to electrical conductivity only.
Periodicity of bond type. Elements Na, Mg, Al, Si, S, Cl, Ar: their electronic structures, their ions (valency), mode of combination in oxide and chloride; inertness of noble gases; chemical and physical properties of metals and non-metals (across a period). Elements: fluorine, chlorine, bromine and iodine (down group). Electronic configuration, graduation in size of atom and ion, reactions. Elements Li, Na, K.
Section 11: Carbon Chemistry
Diamond and graphite (note charcoals). Structure and physical properties.
Carbon monoxide. Combustion, reducing action, poisonous fumes (car exhausts, coke fire "sigiri").
- Laboratory preparation not required.
- Reducing action illustrated with copper (II) oxide + blast furnace.
Carbon dioxide. Preparation, reaction with water, lime water. Weather, boiler "scale"; no detailed treatment of hard water.
Carbonate and hydrocarbonates. Action of heat, dilute acids. Production of soda ash (Lake Magadi). Carbon and carbon dioxide cycles.
Alkanes (methane to butane). Formulae and combustion only. Natural gas. Paraffin wax. Ethene: formulae and combustion. Preparation of ethene by dehydration of ethanol: reaction with bromine.
- A detailed study of the organic chemistry of alkanes, alekenes, alkanols, etc. is not required.
Section 12: Nitrogen
Nitrogen. Inert character. Compare combustion of Na, Ca, P, S, in N2 and O2.
Ammonia. Laboratory preparation, solubility in water, reaction with air/oxygen (catalyzed and uncatalyzed), copper (II) oxide and chlorine. Reactions of aqueous solution: metal ions, dilute acids. Manufacture of ammonia. Ammonium salts as fertilizers.
Nitric acid. Dilute: reaction with metals, carbonates, hydroxides, oxides. Concentrated: oxidizing action; Fe(II) solution, sulphur, copper metal. Nitrates: action of heat. Acidic nature of nitrogen (IV) oxide. Manufacture of nitric acid.
Section 13: Sulphur
Sulphur dioxide. Preparation (Sulphite + Acid), acid character, bleaching action, test with potassium dichromate (VI). Reducing action is not required. Combination with oxygen (laboratory demonstration, Pt. catalyst).
Sulphuric acid. Dilute: reaction with metals, carbonates and bases. Concentrated: dilution with water, copper (II) sulphate crystals, ethanol, sucrose. Test for sulphate: barium nitrate solution. Manufacture of sulphuric acid (Contact process).
Hydrogen sulphide (iron (II) sulphide and acid). "Bad eggs" smell. Pollution by S, SO2, H2S.
Section 14: Chlorine
Hydrogen chloride (common salt + conc. H2SO4). Deduction of composition of salt gas reactions. (i) KMno4, (ii) iron metal, (iii) direct H2 and Cl2 combination. Tests for gas with ammonia. Aqueous solution of gas; acid properties: metal, carbonates, etc.
Chlorine. Preparation: conc. HCl + Potassium manganate (VII), electrolysis of chloride solutions.
(1) Hydrogen and hydrocarbons (turpentine).
(2) Metals (Na, Zn, Mg)
(3) Non-metals (P, S).
(4) Water and dilute alkali
(5) Bromides and iodides.
(6) Bleaching action.
Test for chlorides: (a) dry solid, (b) aqueous solution. Uses of compounds: disinfectant, bleach, chloroform.
Section 15: Acids and Bases (Acidity and Alkalinity)
Weak and strong acids. pH, electrical conductivity, rate of reaction with marble chips, magnesium, for acids and bases.
- Other examples are tartaric and citric acids instead of HCl.
Role of the solvent. Hydrogen chloride or tartaric acid in mythyl benzene compare with aqueous solutions. React with dry litmus, magnesium marble chips. Reactions of dry and aqueous ammonia.
Importance of H+ (aq) and OH- (aq).
Acids (proton donors), bases (proton acceptors). Use of ionic equations.
Amphoteric oxides: react with acid and alkali (no equations for reaction with alkali).
Section 16: Ion Chemistry
Precipitation reactions involving the following ions: Mg2+ (aq), Ca2+ (aq), Fe3+ (aq), Al3+ (aq), Zn2+ (aq), Cu2+ (aq), Fe2+ (aq), with Cl- (aq), OH- (aq), CO
Complex ions: limited to dissolving of specific metal hydroxides in excess ammonia solution or sodium hydroxides. Formula of the following required: Cu(NH3)2+ Pb(OH)2-, Al(OH)
- No instructions on equations required.
Redox reactions. Electron transfer.
Displacement reactions as redox reactions: (a) Reducing power: reaction of metal/cation
(b) Oxidizing power of halogens: Cl2, Br2, I2 only.
The role of water in electrolysis products. Preferential discharge of hydrogen and oxygen where appropriate from the following solutions: sodium chloride, dilute sulphuric acid (acidified water), magnesium sulphate.
Electrochemical cell. Qualitative treatment of the electron flow in Zn/Zn2+ (aq)/Cu2+ (aq)/Cu cell.
Section 17: Energy Changes in Chemical, Physical Reactions
Molar heat of vaporization and boiling-point (latent heats). As evidence for interparticle forces. Enthalpy notation (change in H) for exo and endothermic reactions.
Enthalpy chemical reactions. Students should carry out simple quantitative work.
Electrochemical cell. Qualitative look at the electrochemical series. Students can use copper reference, sodium chloride electrolyte and metal strip electrodes. Zn-Cu cell: teacher demonstration and measurement of potential difference. The potential E is not required.
Simple treatment of solar energy as energy from atoms.
Section 18: Reversible Reactions and Reaction Rates
The effect on rate of: concentration, pressure, temperature, surface area, light and catalysts. Only qualitative, descriptive, graphical representation required, quantitative data given to illustrate a qualitative effect.
(1) Marble chips/dilute acids.
(2) Decomposition of H2O2.
(3) Manganese (IV) oxide to catalyze H2O2 decomposition.
(4) Plantinized asbestos to catalyze SO2/O2 combination.
- Candidates will be expected to appreciate the applications of reaction rate to laboratory and industrial processes.
Reversible Reaction Elementary treatment incorporating the idea that two-way reactions can reach a "balance", "equilibrium" is avoided.
- The effect of changing concentration, pressure, temperature on position of equilibrium is not required. The use in industrial processes should be regarded as "optimum" only.
Section 19: Applied Chemistry
The depth of treatment envisaged should not introduce the students to any new concepts. The emphasis is on illustration and application of chemical principles already encountered. Technical details of plant and process are not required. Many of the compounds mentioned in 19.3 in particular, have complex formulae. Students are not required to memorize these formulae. The aim is to show the relationship between structure, properties and uses. (P - practical work, the rest should be covered by the teacher or by students' private reading.
The atmosphere. The industrial isolation of nitrogen, oxygen and noble gases from air. Their uses (to include: for oxygen: steel manufacture, life support, welding; for argon; discharge tubes). Principles and methods of extinguishing fires of different types. Combustion of hydrocarbon fuels (practical work: charcoal, methylated spirit and natural gas. The internal combustion engine as a major source of atmospheric pollution. Brief consideration of alternative to the internal-combustion engine; steam-engines, fuel cells. Sulphur dioxide as a pollutant from the combustion of coal and heating oils. Equilibrium of the atmosphere via the oxygen and carbon dioxide cycles.
Water resources; pollution. Industrial and domestic uses of water. Water treatment: filtration; flouridation and desalination. Hard and soft water: causes and treatment; including ionization methods. Sewage: methods of water treatment; production of methane and fertilizers. The nitrogen cycle: elements necessary fro plant growth: N, P, K, CA, Mg, S. Fertilizers as artificial replacements: ammonium salts, phosphates, nitrates, sulphates. Soaps and non-soapy detergents: manufacture, simple mode of action, change to biodegradable products. Pollution from fertilizers, insecticide, herbicides and other agricultural wastes (only the pollution aspects). Oil pollution of the sea and lakes; dispersal of oil slicks.
Natural and synthetic materials.
Mineral resources/industrial processes. The following processes should be used to illustrate:
(1) The chemical principles already covered in the course.
(2) The influence of the following factors: availability of raw materials, choice of site social and economic factors, health and pollution problems, supply and demand.
(a) Harber process
(b) Manufacture of nitric acid.
(c) Contact process.
(d) Manufacture of soda and salt.
(e) Electrolytic processes:
- sodium extraction
- copper refining
(f) Extraction of iron: manufacture of steel, examples of alloys, brass, solder, duralumin and their composition.
(g) Large-scale extraction of sugar from sugar-cane.