Switching to AQA from OCR Chemistry B

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1 Switching to AQA from OCR Chemistry B If you're thinking of switching to AQA from OCR GCSE in Chemistry B (Gateway Science - J264) for teaching from September 2016, this resource will provide a helpful comparison of the subject content and assessment for each awarding body. It directly compares the OCR Chemistry B specification, with the new specification (8462) for 2016 onwards. Comparison overview Although both specifications are organised by concept, these concepts have been grouped into different topics. This means that the content in the AQA specification can be found in several OCR topics. AQA and OCR also give different emphasis to specific topics. There is flexibility to co-teach the AQA Chemistry and Combined Science: Trilogy (8464) courses. Assessment Two externally assessed written papers (1 hour 45 minutes). Paper 1 assesses sections 1 to 5 of the subject content. Paper 2 assesses sections 6 to 10, but may also include the fundamental principles in sections 1 to 3. Eight required practicals should be carried out by students and may be examined in the written papers to assess practical skills. Three exam papers overall. Two externally assessed written papers: One paper of 1 hour 15 minutes. Covering content in modules C1, C2 and C3 (35% of qualification). One paper of 1 hour 30 minutes. Covering content in modules C4, C5 and C6. Includes 10 mark data response question (40% of qualification). One controlled assessment exam paper (25% of qualification).

2 Content Practicals The required practicals are clearly listed, as are opportunities for development of skills identified in the right-hand column of the specification. These should encourage more practical work, which will motivate students and encourage the transfer of skills across the subject. Opportunities for practical work are flagged in the introduction to each module. Working scientifically WS 1.1 to WS 4.6 'Working scientifically' encompasses all the activities that scientists do. It is woven throughout the specification and written papers. There are cross-references to relevant skills development opportunities in the subject content. Ideas about science Atomic structure and the periodic table A simple model of the atom, symbols, relative atomic mass, electronic charge and isotopes Atoms, elements and compounds C4: Fundamental Concepts Both specifications require recognition and manipulation of chemical symbols and formulae to describe molecular composition and reactions using an understanding of atoms and molecules, elements and compounds.

3 Equations and balancing can be found at Foundation Tier in both specifications. The OCR specification refers to recollection of particular compounds' formulae in an introductory item for each topic entitled 'Fundamental Chemical Concepts'. Recognition of symbols of the first 20 elements Mixtures Fundamental Concepts: C4 There is no equivalent summary topic in the OCR specification, although all of the separation techniques are covered throughout the specification. Definition of a mixture Scientific models of the atom C4a Both specifications refer to developmental stages in the model of atomic structure as an example of the development of a scientific theory Relative electrical charges of subatomic particles Size and mass of atoms Reference to Dalton and Tomson. Atomic Structure: C4a (also refers to masses of subatomic particles). Fundamental concepts: C4 and C4a Both specifications give the relative masses of the fundamental particles. Calculation of the number of protons, neutrons and electrons in a charged particle is Higher Tier only in the OCR specification, but for students of all abilities in the AQA specification Electronic structure C4a The content of both specifications is the same.

4 4.1 2 The periodic table The periodic table C4a C4c C4d The content is similar, although patterns and their explanation are separated into description of respective groups in the OCR specification. Prediction of possible reactivity from the position in the periodic table The development of the periodic table C4c Both specifications consider the contribution of Mendeleev and earlier contributors. OCR specification includes the ideas of Döbereiner and Newlands. OCR Higher Tier: confirmation of Mendeleev's structure through discovery of unknown elements and investigation into atomic structure. Knowledge of isotopes, explaining why the order based on atomic weights is not always correct Metals and non-metals C2c C4b to g There is no equivalent summary topic in the OCR specification, however: Explanation of the formation of positive and negative ions by metals and non-metals is included in the sections on bonding (C4b, C4c). Description of locations in the periodic table is referred to in topics on respective groups (C4d, C4e, C4f). Consideration of metallic properties is in the topic on metals and alloys (C2c, C4g). OCR doesn t cover differences in properties Group 0

5 Group 1 C4d The content is very similar in both specifications: reactions of the alkali metals with water trends in reactivity moving down the group. Comparison of Group 1 metals' density with water. Reference to reactions and associated products of Group 1 metals with non-metals Group 7 Construction of balanced symbol equations for reactions with water (both Foundation and Higher Tier). Flame tests (identical content is covered in section of the AQA specification). C4e The content is very similar. Both specifications include reactions with metals (alkali metals in the OCR specification) and displacement reactions leading to the pattern in reactivity down the group. OCR Higher Tier: recall the formulae of bromides and iodides. AQA specification requires students of all abilities to know the formulae of the halide ions. The ionic or molecular nature of the products formed with metals and non-metals. Recall of some uses of Group 7 elements. Colours and physical states of the halogens at room temperature Properties of transition elements Comparison with Group 1 elements Typical properties C4f C4f The OCR specification has more detail, it includes identification based on position in the periodic table and physical properties with specific

6 examples of colour and examples of uses as catalysts. Description of thermal decomposition reactions of transition metal carbonates with word equations (Foundation Tier). Higher Tier: balanced symbol equations. Bonding, structure and the properties of matter Chemical bonds, ionic, covalent and metallic Chemical bonds C4b to c C4g There is no equivalent summary-section in the OCR specification. However, OCR covers all the points in topics for each type of bonding Ionic bonding C4b The content is very similar in both specifications: formation and transfer of ions to form compounds. Dot and cross diagrams to represent ionic bonding are required by students of all abilities in the AQA specification while this is Higher Tier only in the OCR specification. AQA specification requires working out the charge on ions from Groups 1, 2, 6 and Ionic compounds OCR requires deducting the formula for an ionic compound from the formula of the positive and negative ions. C4b Both specifications include a description of giant ionic structures. Recognition of a giant ionic structure from a diagram or model. Deduction of the empirical formula from the model and a description of Knowledge of sodium chloride and magnesium oxide structures, comparison of their physical properties.

7 its limitations in representing a giant structure. Reference to sodium chloride Covalent bonding Higher Tier: explanation of differences in these properties (structure, bonding and prediction of the properties of other substances with similar structure). C4c and C3h Description of covalent bonding: shared electrons with reference made to small molecules, polymers and giant covalent structures. Dot and cross diagrams are required for 8 specific molecules at both Higher and Foundation Tiers. Deduction of molecular formula from a given model or diagram and a description of the model's limitations Metallic bonding Carbon dioxide and water as small covalent molecules; description of their physical properties. Higher Tier: explanation of these properties in terms of structure and bonding dot and cross diagrams. C The content is similar, but is Higher Tier only in the OCR specification, unlike in the AQA specification How bonding and structure are related to the properties of substances The three states of matter State symbols This topic is not covered in the OCR specification although an understanding of most of the ideas is assumed, eg in C1g, Smells, and C1h, Paints and Pigments. C5h

8 The content is the same, but in the OCR specification recall of state symbols is for students of all abilities and writing balanced equations, including state symbols, is Higher Tier only. Both are for students of all abilities in the AQA specification Properties of ionic compounds C4b Description of the structure of ionic compounds is similar in both specifications. Knowledge of sodium chloride only Properties of small molecules Knowledge of both sodium chloride and magnesium oxide. C1a, C1e and C4c The content of both specifications is almost the same. The knowledge that intermolecular forces increase with size of molecules and the effect on boiling point is included in the OCR specification in the hydrocarbons context Polymers C1d, C1e and C4b The content of both specifications is very similar: awareness of a polymer's structure and the effect of intermolecular forces on melting point Giant covalent structures The effect of intermolecular forces on strength, stiffness and hardness of a polymer. C3h Understanding of giant covalent structure is similar in both specifications. The OCR topic is covered in the context of allotropes of carbon. Explanation of structure and bonding properties is required at Higher Tier only. Examples of diamond, graphite and silica. Examples of diamond and graphite only.

9 Properties of metals and alloys C2c and C4g The description of metal structures and properties is similar in both specifications. A detailed explanation for the difference in properties between an alloy and its compositional metals Metals as conductors Recollection of the main metals in amalgam, brass and solder with examples of use. Limited to recognition of the differences only. Higher Tier: detailed description of metallic bonding and its effect on properties. C4g Both specifications cover electrical conductivity. OCR Higher Tier: explanation of electrical conductivity. Thermal and electrical conductivity Structure and bonding of carbon Diamond C3h The content is almost identical in both specifications. OCR specification also includes solubility as a property Graphite C3h The content is similar in both specifications. AQA specification describes the bonding of graphite in detail Graphene and fullerenes C3h

10 Detailed explanation of the structure of graphene, fullerenes and carbon nanotubes. OCR specification doesn t refer to graphene. Detailed structure of fullerenes is not required, although an explanation of the structure of nanotubes is required at Higher Tier Bulk and surface properties of matter including nanoparticles Sizes of particles and their properties C3h Both specifications consider the relative size of nanoparticles and the effect on their properties. A mathematical consideration of surface area to volume ratio Uses of nanoparticles C3h The applications of nanoparticles are different in the two specifications. Quantitative chemistry Conservation of mass and the quantitative interpretation of chemical equations Conservation of mass and balanced chemical equations C1 to 6 Fundamental Chemical Concepts C3d C5a The OCR specification covers balanced chemical equations as a fundamental concept respective to each section of the specification. Detailed conservation of mass and how this quantitatively relates to

11 balanced equations is found in section C3d and C5a Relative formula mass C1 to 6 - Fundamental Chemical Concepts C3d C5a In the OCR specification construction of balanced chemical equations is referred to as a fundamental concept prior to each respective section. The use of formula mass to construct equations and perform quantitative calculations is found in section C3d and C5a Mass changes when a reactant or product is a gas Uses of amount of substance in relation to masses of pure substances Moles (Higher Tier only) C5a and C5b This content is similar in both specifications. Avogadro constant Amounts of substances in equations C5a and C5b Both specifications require the calculation of masses and products from balanced equations (Higher Tier only). Mathematical skills: substitution, rearranging equations, standard form and mathematical symbols Using moles to balance equations (Higher Tier only) This topic is not covered in the OCR specification. Although similar knowledge and skills are used in C5a and C5b.

12 Limiting reactants (Higher Tier only) Concentration of solutions C3a This concept is addressed in the context of reaction rates. C5c The procedure for making up a standard solution for students of all abilities. Both specifications consider concentration in g/dm 3 and require calculations involving mass, concentration and volume of solution (Higher Tier only) Yield and atom economy of chemical reactions Percentage yield C2e C3e C6d Both specifications require the calculation of percentage yield given actual and theoretical yield for students of all abilities. They also require calculating the theoretical amount of a product form a balanced equation (Higher Tier only in the OCR specification). Reasons for the actual yield being less than the theoretical yield Atom economy The concept is referred to in evaluation of different processes in C2e and C6d. C3e Content is similar in both specifications. Calculation of atom economy is for students of all abilities. In the OCR specification explanation of industrial ramifications is Higher Tier only.

13 4.3.4 Using concentrations of solutions in mol/dm Using concentrations of solutions in mol/dm 3 C5c C5d Concentrations, titrations and titration calculations are addressed similarly in both specifications Use of amount of substance in relation to volumes of gases Use of amount of substance in relation to volumes of gases C5e This content is similar in both specifications. However, the OCR specification focuses on measurement of gases and limiting reactants for students of all abilities. Higher Tier: calculations involving amounts and volumes of gas (both specifications). Chemical changes Reactivity of metals Metal oxides C2d C4d C6c Oxidation and reduction are defined in terms of gain and loss of oxygen in both specifications. The OCR specification focuses on rusting. There is reference to the oxidation of metals in C2d and C4d The reactivity series C6c C4d

14 The AQA specification covers reactivity in detail; it refers to an element's tendency to form positive ions denoting its position in the reactivity series. OCR specification covers the reactivity of Group 1 metals in section C4d. A series of 8 metals with a prediction of their displacement reactions Extraction of metals and reduction The OCR specification refers to a series of 4 metals with a prediction of their displacement reactions. C2c C6c Both specifications cover extraction of metals by carbon reduction. They also require evaluation of specific metal extraction processes. Unreactive metals such as gold Oxidation and reduction in terms of electrons Focus on copper extraction. C2c C6c Higher Tier content including ionic equations (both specifications) Reactions of acids Reactions of acids with metals Neutralisation of acids and salt production No equivalent in the OCR specification. However, metal/acid redox reactions are used in sections C3a, C3b and C3c in studying rate of reaction. Metal displacement reactions are referred to in section C6c. C2f

15 The content is very similar in both specifications: definition of alkalis (however, only AQA defines a base) production of salts from acids with metal oxides, hydroxides or carbonates deduction of the name and formula of the salt formed (deduction of a formula is at Higher Tier only in OCR) Soluble salts C4h C5h Both specifications cover production, purification and drying of a soluble salt. The process is limited to the use of an insoluble starting material. There is a required practical to make a salt from an insoluble oxide or carbonate The ph scale and neutralisation Preparation of an insoluble salt is a suggested activity in section C4h. Students are required to recall stages in the preparation of a dry sample in section C5h. C2f C5d The content is similar in both specifications: ionic equation for neutralisation litmus paper, universal indicator and ph probes acid-alkali titrations, although there are some differences in the treatment of these. Ionic equations for neutralisation reactions are required by students of all abilities (Higher Tier only in the OCR specification). A required practical for students of all abilities. Higher Tier: calculate the concentration of one of the solutions, either in g/dm 3 or mol/dm 3. Higher Tier: perform calculations involving concentration, mass, volume and balanced equations, although students of all abilities may be given a formula in which to substitute results. All students are expected to recall how to make up a standard solution and to estimate the uncertainty in the results.

16 Strong and weak acids C5g Both specifications give examples of acids, although the lists are not the same. Both describe strong and weak acids in terms of ph. The entire topic is at Higher Tier only in the AQA specification. Description of extent of ionisation and the mathematical link between ph and hydrogen ion concentration Electrolysis The process of electrolysis C6a The content of both specifications is very similar. Throughout the electrolysis topic, Higher Tier students are expected to write and balance half-equations for reactions at the electrodes Electrolysis of molten ionic compounds C6a Common content in both specifications: lead bromide as an example production of metals at the negative electrode and non-metals at the positive electrode half equations are required at Higher Tier. The terms anode and cathode Using electrolysis to extract metals C2c The AQA example: aluminium. The OCR example: extraction of copper.

17 Electrolysis of aqueous solutions Higher Tier: gain or loss of electrons at the electrodes. C6a Content is similar in both specifications. OCR focuses on brine and sulphuric acid. There is a required practical investigating the electrolysis of aqueous solutions using inert electrodes Representation of reactions at electrodes as half equations Students of all abilities: knowledge of the products at both electrodes. Higher Tier: half equations (both tiers in AQA). Energy changes Exothermic and endothermic reactions Energy transfer during exothermic and endothermic reactions C3f Both specifications require an understanding of the terms exothermic and endothermic. AQA specification is more detailed. Examples of exothermic and endothermic changes. The link between energy change and temperature change. Everyday uses of exothermic and endothermic reactions. There is a required practical investigating the factors affecting temperature changes in a list of

18 possible reaction mixtures Reaction profiles C6b The OCR specification refers to energy level diagrams rather than energy profiles. Both include activation energy. This is Higher Tier only in the OCR specification The energy change of reactions C3f Content common in both specifications: energy needed to break bonds and energy released on forming bonds (for students of all abilities in OCR, Higher Tier in AQA) calculation of the overall energy change from bond energy data (Higher Tier only) Chemical cells and fuel cells Cells and batteries Fuel cells C6b The content is very similar in both specifications: overall reaction (Higher and Foundation Tier) half equations (Higher Tier only). The rate and extent of chemical change Rate of reaction Calculating rates of reactions C3a The OCR specification requires students to explain meaning of a

19 chemical reaction rate, including the use of appropriate units and interpretation of data. The AQA specification is more detailed and requires further calculation. Rate of reaction is defined mathematically for students of all abilities, using units of g/s or cm 3 /s. Higher Tier: using units involving moles. All students are required to draw and interpret graphs, including drawing tangents to the curve and using the slope as a measure of rate. Higher Tier: calculating the gradient of a tangent to the curve Factors which affect the rates of chemical reactions C3b Both specifications include the effect of size of solid particles, concentration of solutions, temperature and the presence of a catalyst. Both require knowledge of how rate can be followed by collecting a gas, weighing the mixture and formation of a precipitate or colour. The effect of gas pressure. Students are required to explain the effect of size of pieces of solid in terms of surface area to volume ratio. Students are required to interpret information about the control of rates of reaction in chemical synthesis. There is a required practical investigating how concentration changes affect the rate of a reaction Collision theory and activation energy C3b C3c Both specifications use collision frequency to explain how rate depends on the concentration of a solution, but there are significant differences in the rest of the topic.

20 Surface area to volume ratio is required to explain the effect of changing the size of pieces of a solid. Energy of collisions and activation energy is required to explain the effect of temperature changes. The effect of pressure changes is also explained by collision frequency Factors that increase the rate of reaction The effect of changing the size of pieces of a solid is explained in terms of collision frequency. The effect of temperature changes is not covered. C3b C3c Both specifications cover the effect of changing the concentration of a solution and the size of pieces of solid in terms of collision frequency. The effect of pressure and temperature changes. The effect of temperature changes on the energy of collision. Students are expected to predict and explain the effect of changing conditions and to use simple ideas about proportionality when using collision theory Catalysts C3c Both specifications define a catalyst. AQA specification explains it provides an alternative route of lower activation energy. Reaction profiles Reversible reactions and dynamic equilibrium Reversible reactions C2e

21 The content is similar in both specifications. However, in the ammonium chloride dissociation example the AQA specification refers to changing the conditions to change the direction Energy changes and reversible reactions Equilibrium This topic is not covered in the OCR specification. However, it may be implicit in the effect of temperature change on equilibrium (C5f). C5f Both specifications refer to a reversible reaction reaching equilibrium. OCR Higher Tier: dynamic equilibrium, the contact process and explanation of its conditions The effect of changing conditions on equilibrium (Higher Tier only) Le Chatelier's principle The effect of changing concentration (Higher Tier only) The effect of temperature changes on equilibrium C2f C2f C2f Full explanation of this topic is at Higher Tier only for both specifications. The AQA specification goes into more detail, students are required to predict the effect of a change in temperature on given reactions at equilibrium, in terms of their endothermic/exothermic character The effect of pressure changes on equilibrium C2f The OCR specification requires description by students of all abilities and explanation at Higher Tier. Higher Tier only in the AQA specification. Students are required to predict the effect of a change in pressure on given reactions at equilibrium, in terms of the number of molecules on each side of the

22 balanced equation. Organic chemistry Carbon compounds as fuels and feedstock Crude oil, hydrocarbons and alkanes C1a C1d The content is very similar in both specifications. The origin of crude oil; the general formula for alkanes Fractional distillation and petrochemicals C1a The content is very similar in both specifications. AQA emphasises the ability of carbon atoms to form families of similar compounds with the consequential vast array of natural and synthetic compounds Properties of hydrocarbons Higher Tier: detailed explanation for fractions' different boiling points. C1a C1b Both specifications include the effect of molecule size on boiling point. They also cover the complete combustion of hydrocarbons as oxidation. The trends of viscosity and flammability with molecular size, their influence on the use of hydrocarbons as fuels. Students of all abilities are expected to write balanced equations for combustion reactions.

23 Cracking and alkenes C1a C1d The content is very similar, but OCR splits it across two sections. Students of all abilities are required to balance chemical equations that represent cracking using formulae of reactants and products Reactions of alkenes and alcohols Structure and formulae of alkenes C1d Nearly all of the content is specific to AQA specification. The C=C functional group, the general formula, the structures of the first four alkenes Reactions of alkenes C1d C1b C6d The synthetic route for conversion of ethane to ethanol via ethene is covered in section C6d. Combustion of hydrocarbons is referred to in C1b, alkenes aren t mentioned. Addition reactions and the formation of dibromo compounds is covered in section C1d. The reaction of alkenes with oxygen, hydrogen, water and halogens. The displayed formulae for the first four alkenes.

24 Alcohols C6d The content is similar in both specifications: names, formulae, functional group, structures and uses of methanol and ethanol combustion and reaction with sodium (Higher Tier only in OCR). Propanol and butanol Carboxylic acids Fermentation is covered in more detail, including limits to the concentration of ethanol produced in fermentation and concentration of the solution by distillation. Comparison and evaluation of fermentation and hydration as production methods. C1g C5g C6g The AQA specification is more detailed. The OCR specification refers to their nature as weak acids (C5g), reaction with alcohols to produce esters (C1g) and within the context of fats and oils (C6g). Propanoic, butanoic and acids; their structural formulae. In item C1g the OCR specification covers the properties and uses of esters and a detailed method for their preparation. Perfumes and animal testing of cosmetics are covered in detail in section C1g. Saponification using sodium hydroxide is covered in section C6g (both for Foundation and Higher Tiers).

25 4.7.3 Synthetic and naturally occurring polymers Addition polymerisation C1d Both specifications cover polymerisation as the joining of many monomers to form long chains. OCR Higher Tier: drawing the displayed formula of an addition polymer. Poly(ethene) and poly(propene) Condensation polymerisation Amino acids DNA and other naturally occurring polymers This topic is not covered in the OCR specification. However, proteins and denaturation are mentioned in cooking context (C1f). Nylon and Gore-Tex as examples of designer polymers (C1e). Chemical analysis Purity, formulations and chromatography Pure substances C3g Both specifications cover identification of pure substances based on comparison of physical properties with less pure counterparts. Definition of purity Formulations This topic is not covered in the OCR specification. However, fuels, paints, alloys, fertilisers and foods are referred to in sections C1b, C3f and C6b (fuels),

26 C1h (paints), C2c and C2d (alloys), C2g (fertilisers) and C1f (foods) Chromatography The OCR specification details not present in the AQA specification: C1h - Paints and Pigments C1f - Emulsifiers C6g - Natural Fats and Oils C6h - Detergents C3g C6h The AQA specification is more detailed. The OCR specification only refers to chromatography in terms of extraction of chemicals from plants and elucidating the purity of a substance through thin layer chromatography. Solvents are discussed in other areas of the OCR specification without reference to chromatography, eg in C1g, Smells and C1h, Paints and Pigments There is a required practical investigating the chromatography of coloured substances and calculation of R f values Identification of common gases Test for hydrogen C6a The content of both specifications is the same Test for oxygen C6a The content of both specifications is the same.

27 Test for carbon dioxide Definition of limewater as an aqueous solution of calcium hydroxide Test for chlorine C1f C2h The content of both specifications is the same Identification of ions by chemical and spectroscopic means Flame tests C4d Both specifications require knowledge of flame tests and recollection of flame colours for lithium, sodium and potassium. Content includes flame colours for calcium and copper Metal hydroxides C4f Both specifications cover the precipitation of metal hydroxides as an identification method for metal ions, although the list of ions is slightly different Carbonates An understanding of precipitation in the context of formation of an insoluble compound. Higher Tier: ionic equations for precipitation reactions. Reactions of carbonates in terms of thermal decomposition and reactions with acids are covered in several areas of the OCR specification. Solubility in water is only mentioned in terms of water hardness and calcium carbonate.

28 The pattern of solubility of carbonates Halides C4h The content of both specifications is the same Sulfates C4h The content of both specifications is the same Instrumental methods General advantages of instrumental methods Flame emission spectroscopy Students are expected to interpret a spectrum, given appropriate data. There is a required practical to identify the ions in a single ionic compound using the test tube reactions. Chemistry of the atmosphere The composition and evolution of the Earth's atmosphere The proportions of different gases in the atmosphere C1c The content of both specifications is very similar The Earth's early C1.1.5 to 6

29 atmosphere C The content of both specifications is almost the same. A consideration of how theories about the early atmosphere have changed; limitations of the evidence. Higher Tier: detailed description of atmospheric evolution. The presence of nitrogen, methane and ammonia How oxygen increased C1c The content of both specifications is the same. The chemical equation for photosynthesis How carbon dioxide decreased C1c The content is similar, but the AQA specification goes into more detail about the formation of limestone, coal and crude oil Carbon dioxide and methane as greenhouse gases Greenhouse gases Human activities which contribute to an increase of greenhouse gases in the atmosphere Global climate change The mechanism of the greenhouse effect in terms of radiation of different wavelengths is not covered in the OCR specification. The increase of carbon dioxide and methane in the atmosphere is not covered in the OCR specification except for a brief mention of carbon dioxide as a greenhouse gas in C1b. The potential effects of climate change are not covered in the OCR specification.

30 The carbon footprint and its reduction C6e: The OCR specification covers CFCs and the depletion of the ozone layer in detail Common atmospheric pollutants and their sources Atmospheric pollutants from fuels C1b C1c The content is very similar in both specifications: the formation of carbon dioxide, carbon monoxide, carbon, sulfur dioxide and oxides of nitrogen particulates Properties and effects of atmospheric pollutants C1b C1c Much of the content is the same: carbon monoxide's effect on the blood sulfur dioxide and oxides of nitrogen causing acid rain. The effect of particulates on global dimming. The respiratory effects of particulates, sulfur dioxide and oxides of nitrogen.

31 Using resources Using the Earth's resources and obtaining potable water Using the Earth's resources and sustainable development Not covered in the OCR specification. However, ideas regarding the use of chemistry to improve processes can be found in section C3e, Percentage Yield and Atom Economy and C3g, Batch or Continuous. Similar ideas are covered in both specifications; both refer to natural and synthetic materials, but use different examples. The AQA specification refers to finite and renewable resources and to sustainable development. The OCR specification focuses on the properties of materials; sustainability is developed in other areas throughout the specification Potable water C2a Earth's geology is covered in detail. The use of limestone as a building material, including the production of cement and concrete (C2b). The acquisition of salt and the chlor-alkali industry are covered in detail in C2h. C3a The development of pharmaceutical drugs and batch and continuous production processes are covered in detail. C4h The content of both specifications is very similar. C6f Water hardness and its removal are covered in detail.

32 Waste water treatment Alternative methods of extracting metals Phytomining and bioleaching is not covered in the OCR specification, except for copper extraction mentioned in C2c Life cycle assessment and recycling Life cycle assessment Ways of reducing the use of resources There is no reference to this content in the OCR specification although consideration is given to the environmental impact of a variety of chemical products, particularly polymers, in C1e. C1e C2c to 2d Both specifications cover recycling of metals and environmental impacts of extracting metals. However, OCR specification does not consider other materials. Recycling polymers is also considered at Higher Tier in the OCR item C1e. Reduction in use of materials and reuse (for example of glass bottles); recycling. Resources also include glass, building materials and ceramics. The energy required coming from limited resources Using materials Corrosion and its prevention C2d C6c

33 Alloys as useful materials Higher Tier: the disadvantages of using tin plate for protection against rusting. C2c The content is very similar in both specifications, however they use different examples. AQA specification goes into more detail, eg the carat system for alloys of gold. Bronze, steel, gold alloys and aluminium alloys Ceramics, polymers and composites Amalgam, brass and solder. C2b The AQA specification goes into more detail and provides more examples. Glass, ceramics, composites and polymers. The specification includes the properties of polymers depending on the monomer used and the conditions under which they are made, using LDPE and HDPE as examples. Polymers are classified as thermo softening or thermosetting. Glass's relationship with sand and brick's with clay. There is no mention of low or high density poly(ethene) or thermo softening or thermosetting polymers The Haber process and the use of NPK fertilisers The Haber process C2e The content is very similar in both specifications. The principles of dynamic equilibrium are at Higher Tier in the AQA specification, but only a simple explanation of the effect of changing temperature and pressure is required at the same tier by OCR. The relationship between commercially used conditions and cost/availability is referred to by both

34 specifications. The removal of ammonia from the reaction mixture by cooling Production and uses of NPK fertilisers A balanced symbol equation is used at both tiers (although partly given at foundation tier). Although the use of fertilisers is covered in C2g, there is no reference to the production of NPK fertilisers. Eutrophication is covered in detail in C2g.