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Switching to AQA from OCR Chemistry B If you're thinking of switching to AQA from OCR B Science and Additional Science (J261 and J262) 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 B Science and Additional Science (J261 and J262) with the Chemistry component of the new AQA GCSE Combined Science: Trilogy specification for 2016 onwards.
Comparison overview The style of the two specifications is very different, with the AQA content being organised by concept, and the OCR content being organised by context. This means that the content in the AQA specification is often widely scattered in the OCR specification and vice versa, and even when the content is similar, the emphasis is very different. There is some repetition in the OCR specification where ideas are required in more than one context.
Assessment New AQA specification Current OCR specification
Two externally assessed written papers (1 hour 10 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.
Five required practicals should be carried out by students and may be examined in the written papers to assess practical skills.
The content is assessed as part of four externally assessed written papers, each of which assesses biology and physics content as well as chemistry, and two controlled assessments marked internally:
• One paper of 1 hour 15 minutes, covering content in module C1 (as well as B1 and P1) (17.5% of qualification).
• One paper of 1 hour 30 minutes, covering content in module C2 (as well as B2 and P2). Includes 10 mark data response question (20% of qualification).
• One paper of 1 hour 15
minutes, covering content in module C3 (as well as B3 and P3) (17.5% of qualification).
• One paper of 1 hour 30 minutes, covering content in module C4 (as well as B4 and P4). Includes 10 mark data response question (20% of qualification).
• Two controlled assessments (12.5% of qualification each). A choice of one from three tasks is available for the Science qualification, and a choice of one from six for the Additional Science qualification. Each includes research and planning as well as collection of primary data through practical work and analysis of that data.
Content
Practicals
New AQA specification Current OCR specification
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
New AQA specification Current OCR specification
New AQA specification Current OCR specification
Specification reference: WS 1.1 to WS 4.6
Specification reference: Ideas about science
'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.
N/A
Atomic structure and the periodic table
5.1.1 A simple model of the atom, symbols, relative atomic mass, electronic charge and isotopes
New AQA specification Current OCR specification
Specification reference:
5.1.1.1 Atoms, elements and compounds
Specification reference:
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.
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.
N/A
Specification reference:
5.1.1.2 Mixtures
Specification reference:
C1a
C3g
C4h
New AQA specification Current OCR specification
There is no equivalent summary topic in the OCR specification, although most of the separation techniques are covered throughout the specification, for example filtration and distillation in the context of purifying and testing water (C4h), or chromatography in the context of purification of a compound (C3g).
The specification includes a definition of a mixture.
Crystallisation is not covered.
Specification reference:
5.1.1.3 Scientific models of the atom
Specification reference:
C4a
Both specifications refer to developmental stages in the model of atomic structure as an example of the development of a scientific theory.
N/A Reference to Dalton and Thomson.
Specification reference:
5.1.1.4 Relative electrical charges of subatomic particles
Specification reference:
C4a: Atomic Structure (also refers to masses of subatomic particles).
Specification reference:
5.1.1.5 Size and mass of atoms
Specification reference:
C4: Fundamental concepts 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.
Specification reference:
5.1.1.6 Electronic structure
Specification reference: C4a
The content is identical.
5.1 2 The periodic table
New AQA specification Current OCR specification
Specification reference:
5.1.2.1 The periodic table
Specification reference:
• C4a
• C4c
New AQA specification Current OCR specification
• 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.
N/A
Specification reference:
5.1.2.2. The development of the periodic table
Specification reference: C4c
Both specifications consider the contribution of Mendeleev, and of earlier contributors, with the OCR specification including the ideas of Döbereiner and Newlands specifically. The OCR Higher Tier includes 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, is included.
N/A
Specification reference:
5.1.2.3 Metals and non-metals
Specification reference:
• 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).
The OCR specification does not cover the differences in properties.
Specification reference:
5.1.2.4 Group 0
This topic is not covered in the OCR specification.
New AQA specification Current OCR specification
Specification reference:
5.1.2.5 Group 1
Specification reference:
C4d
The content is very similar in both specifications, with both including the reactions of the alkali metals with water and trends in reactivity moving down the group.
The specification includes a comparison of Group 1 metals' density with water and a reference to reactions and associated products of Group 1 metals with non-metals.
The specification includes the construction of balanced symbol equations for reactions with water (both Foundation and Higher Tier), and flame tests (which are not included in the AQA specification).
Specification reference:
5.1.2.6 Group 7
Specification reference:
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. Recall of the formulae of bromides and iodides is at Higher Tier only in the OCR specification, whereas the AQA specification requires students of all abilities to know the formulae of the halide ions.
The specification includes the ionic or molecular nature of the products formed with metals and with non-metals.
The specification includes recall of some uses of Group 7 elements, and the colours and physical states of the halogens at room temperature.
N/A Specification reference:
C4f
Transition metals are not included in the AQA specification.
The specification includes a section on Transition metals, including decomposition of the carbonates and reactions of the cations with sodium hydroxide solution.
5.2 Bonding, structure and the properties of matter
5.2.1 Chemical bonds, ionic, covalent and metallic
New AQA specification Current OCR specification
Specification reference:
5.2.1.1 Chemical bonds
Specification reference:
• 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.
Specification reference:
5.2.1.2 Ionic bonding
Specification reference:
C4b
The content is very similar in both specifications, in terms of the 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 7.
OCR requires deducting the formula for an ionic compound from the formula of the positive and negative ions.
Specification reference:
5.2.1.3 Ionic compounds
Specification reference:
C4b
Both specifications include a description of giant ionic structures.
The specification includes the recognition of a giant ionic structure from a diagram or model, the deduction of the empirical formula from the model and a description of its limitations in representing a giant structure. There is a specific reference to the sodium chloride structure.
The specification includes a knowledge of sodium chloride and magnesium oxide structures, and a comparison of their physical properties. At Higher Tier only, an explanation of the differences in these properties is required.
Specification reference:
5.2.1.4 Covalent bonding
Specification reference:
• C4c
• C3h
New AQA specification Current OCR specification
Both specifications include a description of covalent bonding as shared electrons, with reference made to small molecules, polymers and giant covalent structures.
Dot and cross diagrams are required at both Higher and Foundation Tiers. Deduction of molecular formula from a given model or diagram and a description of the model's limitations are also required.
The specification includes carbon dioxide and water as small covalent molecules and a description of their physical properties. At Higher Tier only, an explanation of these properties in terms of structure and bonding is required, as well as dot and cross diagrams.
Specification reference:
5.2.1.5 Metallic bonding
Specification reference:
C4g
The content is similar, but is Higher Tier only in the OCR specification, unlike in AQA specification.
5.2.2 How bonding and structure are related to the properties of substances
New AQA specification Current OCR specification
Specification reference:
5.2.2.1 The three states of matter
This topic is not covered in the OCR specification although an understanding of most of the ideas is assumed in other areas such as C1g Smells and C1h Paints and Pigments.
Specification reference:
5.2.2.2 State symbols
This topic is not covered in the OCR specification
Specification reference:
5.2.2.3 Properties of ionic compounds
Specification reference:
C4b
Description of the structure of ionic compounds is similar in both specifications.
The specification requires knowledge of the sodium chloride structure only.
The specification requires knowledge of both sodium chloride and magnesium oxide structures.
New AQA specification Current OCR specification
Specification reference:
5.2.2.4 Properties of small molecules
Specification reference:
• C1a
• C1e
• C4c
The content 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.
Specification reference:
5.2.2.5 Polymers
Specification reference:
• C1d
• C1e
• C4b
The content is very similar, including awareness of a polymer's structure and the effect of intermolecular forces on melting point.
N/A The effect of intermolecular forces on strength, stiffness and hardness of a polymer are included.
Specification reference:
5.2.2.6 Giant covalent structures
Specification reference:
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.
The specification includes the examples of diamond, graphite and silica.
The specification includes the examples of diamond and graphite only.
Specification reference:
5.2.2.7 Properties of metals and alloys
Specification reference:
• C2c
• C4g
The description of metal structures and properties is similar in both specifications.
The specification includes explanation for the difference in properties between an alloy and
The specification includes recollection of the main metals in amalgam, brass and solder with
New AQA specification Current OCR specification
its compositional metals. examples of uses. At Higher Tier only, a detailed description of metallic bonding and its effect on properties is included.
Specification reference:
5.2.2.8 Metals as conductors
Specification reference:
C4g
Both specifications cover electrical conductivity. The explanation of electrical conductivity is at Higher Tier only in the OCR specification.
Thermal conductivity is included as well as electrical.
N/A
5.2.3 Structure and bonding of carbon
New AQA specification Current OCR specification
Specification reference:
4.2.3.1 Diamond
Specification reference:
C3h
The content is almost identical in both specifications. The OCR specification also includes insolubility as a property.
Specification reference:
4.2.3.2 Graphite
Specification reference:
C3h
The content is similar in both specifications.
Specification reference:
4.2.3.3 Graphene and fullerenes
Specification reference:
C3h
The specification includes an explanation of the structure of graphene, fullerenes and carbon nanotubes.
The specification does not refer to graphene. The detailed structure of fullerenes is not required, although an explanation of the structure of nanotubes is required at Higher Tier.
Specification reference:
C3h
The specification does not include nanotechnology.
The specification includes some ideas about nanotechnology.
5.3 Quantitative chemistry
5.3.1 Conservation of mass and the quantitative interpretation of chemical equations
New AQA specification Current OCR specification
Specification reference:
5.3.1.1 Conservation of mass and balanced chemical equations
Specification reference:
• C1 to 4 Fundamental Chemical Concepts
• C3d
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 balanced equations is found in section C3d.
Specification reference:
5.3.1.2 Relative formula mass
Specification reference:
• C1 to 4 - Fundamental Chemical Concepts
• C3d
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.
Specification reference:
5.3.1.3 Mass changes when a reactant or product is a gas
This topic is not covered in the OCR specification.
5.3 2 Uses of amount of substance in relation to masses of pure substances
New AQA specification Current OCR specification
Specification reference:
5.3.2.1 Moles (Higher Tier only)
This topic is not covered in the OCR specification.
Specification reference:
5.3.2.2 Amounts of substances in equations
Specification reference:
C3d
Both specifications require the calculation of masses and products from balanced equations, at Higher Tier only. The AQA specification uses the moles approach, whereas the OCR specification does not include moles.
New AQA specification Current OCR specification
Specification reference:
5.3.2.3 Using moles to balance equations (Higher Tier only)
This topic is not covered in the OCR specification.
Specification reference:
5.3.2.4 Limiting reactants (Higher Tier only)
Specification reference:
C3d
The OCR specification includes only a passing reference to the mass of product being proportional to that of the limiting reactant.
Specification reference:
5.3.2.5 Concentration of solutions (Higher Tier only)
This topic is not covered in the OCR specification, although concentration is mentioned in the context of rate of reaction.
N/A Specification reference:
C3e
The specification includes calculation of percentage yield and atom economy.
5.4 Chemical changes
5.4.1 Reactivity of metals
New AQA specification Current OCR specification
Specification reference:
5.4.1.1 Metal oxides
Specification reference:
• C2d
• C4d
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.
Specification reference:
5.4.1.2 The reactivity series
Specification reference:
C4d
New AQA specification Current OCR specification
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.
The specification refers to a series of 8 metals with a prediction of their displacement reactions.
The specification refers to a series of 4 metals with a prediction of their displacement reactions.
Specification reference:
5.4.1.3 Extraction of metals and reduction
Specification reference:
C2c
The OCR specification only includes extraction of copper by carbon reduction.
Specification reference:
5.4.1.4 Oxidation and reduction in terms of electrons
Specification reference:
C2c
This is Higher Tier content including ionic equations in both specifications.
5.4.2 Reactions of acids
New AQA specification Current OCR specification
Specification reference:
5.4.2.1 Reactions of acids with metals
There is no equivalent section in the OCR specification.
However, metal/acid redox reactions are used in sections C3a, C3b and C3c in studying rate of reaction.
Specification reference:
5.4.2.2 Neutralisation of acids and salt production
Specification reference: C2f
New AQA specification Current OCR specification
The content is very similar in both specifications. Both include a definition of alkalis (however, only AQA defines a base), the production of salts from acids with metal oxides, hydroxides or carbonates, and deduction of the name and formula of the salt formed (deduction of a formula is at Higher Tier only in OCR).
Specification reference:
5.4.2.3 Soluble salts
Specification reference:
• C3e
• C4h
The process is limited to the use of an insoluble starting material.
Preparation of insoluble salts is not included.
There is a required practical to make a salt from an insoluble oxide or carbonate.
The OCR content is in the context of chemical economics.
Preparation of an insoluble salt is a suggested activity in section C4h.
Specification reference:
5.4.2 4 The pH scale and neutralisation
Specification reference:
C2f
The content is similar in both specifications, including the ionic equation for neutralisation, and the use of litmus paper, universal indicator and pH probes. An acid-alkali titration is included in the OCR specification in the context of making a fertiliser but is not covered in the AQA specification. Ionic equations for neutralisation reactions are required by students of all abilities by AQA but are Higher Tier only in the OCR specification.
Specification reference:
5.4.2.5 Strong and weak acids (Higher Tier only)
This topic is not covered in the OCR specification
5.4.3 Electrolysis
New AQA specification Current OCR specification
Specification reference:
5.4.3.1 The process of electrolysis
This topic is not covered in the OCR specification except in the context of electrolysis of brine (C2h) and purification of copper (C2c).
New AQA specification Current OCR specification
Specification reference:
5.4.3.2 Electrolysis of molten ionic compounds
This topic is not covered in the OCR specification.
Specification reference:
5.4.3.3 Using electrolysis to extract metals
Specification reference:
C2c
In the AQA specification, the extraction of aluminium is covered, whereas the OCR specification covers only the purification of copper.
Specification reference:
5.4.3.4 Electrolysis of aqueous solutions
Specification reference:
C2h
The OCR specification uses brine as the only example, whereas the AQA specification covers solutions in general, including prediction of the products at each electrode.
There is a required practical investigating the electrolysis of aqueous solutions using inert electrodes.
Specification reference:
5.4.3.5 Representation of reactions at electrodes as half equations
Specification reference:
• C2c
• C2h
This topic is at Higher Tier only in both specifications.
5.5 Energy changes
5.5.1 Exothermic and endothermic reactions
New AQA specification Current OCR specification
Specification reference:
5.5.1.1 Energy transfer during exothermic and endothermic
Specification reference: C3f
New AQA specification Current OCR specification
reactions
Both specifications require an understanding of the terms exothermic and endothermic.
There is a required practical investigating the factors affecting temperature changes in a list of possible reaction mixtures.
Specification reference: 5.5.1.2 Reaction profiles
This topic is not covered in the OCR specification.
Specification reference:
5.5.1.3 The energy change of reactions
Specification reference:
C3f
Both specifications refer to energy change in relation to bond breaking and bond making, but is at Higher Tier only for AQA and for students of all abilities for OCR. The OCR specification requires calorimetry calculations, with recall of the formula being at Higher Tier only.
5.6 The rate and extent of chemical change
5.6.1 Rate of reaction
New AQA specification Current OCR specification
Specification reference:
5.6.1.1 Calculating rates of reactions
Specification reference:
C3a
In both specifications rate of reaction is for students of all ability, using units of g/s or cm3/s. The AQA specification includes units involving moles, for Higher Tier only. Both specifications require interpretation of rate as the slope of a graph, with the AQA specification specifically requiring the drawing of a tangent and, for Higher Tier only, calculation of its gradient.
Specification reference:
5.6.1.2 Factors which affect the
Specification reference:
C3b
New AQA specification Current OCR specification
rates of chemical reactions
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 is included. Students are required to explain the effect of size of pieces of solid in terms of surface area to volume ratio.
There is a required practical investigating how concentration changes affect the rate of a reaction.
Students are required to interpret information about the control of rates of reaction in chemical synthesis.
Specification reference:
5.6.1.3 Collision theory and activation energy
Specification reference:
• 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.
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.
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.
Specification reference:
5.6.1.4 Factors that increase the rate of reaction
Specification reference:
• 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.
New AQA specification Current OCR specification
Also included are the effect of pressure and temperature changes, and 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.
Specification reference:
5.6.1.5 Catalysts
Specification reference:
C3c
Both specifications define a catalyst.
The explanation of how a catalyst works by providing an alternative route of lower activation energy, and reaction profiles, are included.
N/A
5.6.2 Reversible reactions and dynamic equilibrium
New AQA specification Current OCR specification
Specification reference:
5.6.2.1 Reversible reactions
Specification reference: C2e
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.
Specification reference:
5.6.2.2 Energy changes and reversible reactions
This topic is not covered in the OCR specification.
Specification reference:
5.6.2.3 Equilibrium
This topic is not covered in the OCR specification.
Specification reference:
5.6.2.4 The effect of changing conditions on equilibrium (Higher Tier only)
Specification reference:
C2e
New AQA specification Current OCR specification
The specification requires the use of Le Chatelier's principle to predict the effect of changing conditions, at Higher Tier only.
The specification requires the interpretation of data in the context of percentage yield in industrial process, with no recall required, for students of all abilities.
Specification reference:
5.6.2.5 The effect of changing concentration (Higher Tier only)
This topic is not covered in the OCR specification.
Specification reference:
5.6.2.6 The effect of temperature changes on equilibrium
Specification reference:
C2e
Full explanation of this topic is at Higher Tier only for both specifications. The AQA specification goes into more detail, with students being required to predict the effect of a change in temperature on given reactions at equilibrium, in terms of their endothermic/exothermic character.
Specification reference:
5.6.2.7 The effect of pressure changes on equilibrium
Specification reference:
C2e
The OCR specification requires use of data by students of all abilities and explanation at Higher Tier. The AQA specification is at Higher Tier only; 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 balanced equation.
5.7 Organic chemistry
5.7.1 Carbon compounds as fuels and feedstock
New AQA specification Current OCR specification
Specification reference:
5.7.1.1 Crude oil, hydrocarbons and alkanes
Specification reference:
• C1a
• C1d
The content is very similar in both specifications.
New AQA specification Current OCR specification
The specification includes the origin of crude oil and the general formula for alkanes.
N/A
Specification reference:
5.7.1.2 Fractional distillation and petrochemicals
Specification reference:
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.
N/A The specification includes, at Higher Tier only a detailed explanation for fractions' different boiling points.
Specification reference:
5.7.1.3 Properties of hydrocarbons
Specification reference:
• C1a
• C1b
Both specifications include the effect of molecule size on boiling point. They also cover the complete combustion of hydrocarbons as oxidation.
The specification includes the trends of viscosity and flammability with molecular size, and their influence on the use of hydrocarbons as fuels. Students of all abilities are expected to write balanced equations for combustion reactions.
N/A
Specification reference:
5.7.1.4 Cracking and alkenes
Specification reference:
• 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.
N/A
New AQA specification Current OCR specification
N/A The OCR specification also includes, in the section on carbon chemistry:
C1d: Making polymers, including the structure and formulae of alkenes and their reaction with bromine
C1e: Designer polymers
C1f: Cooking and food additives, including oils and emulsifiers
C1g: Smells, including natural fats and oils, and esters as solvents
5.8 Chemical analysis
5.8.1 Purity, formulations and chromatography
New AQA specification Current OCR specification
Specification reference:
5.8.1.1 Pure substances
Specification reference:
C3g
Both specifications cover identification of pure substances based on comparison of physical properties with less pure counterparts.
Definition of purity. N/A
Specification reference:
5.8.1.2 Formulations
This topic is not covered in the OCR specification.
However, fuels, paints, alloys, fertilisers and foods are referred to in sections C1b and C3f (fuels), C1h (paints), C2c and C2d (alloys), C2g (fertilisers) and C1f (foods).
N/A The OCR specification includes details not present in the AQA specification:
C1h - Paints and Pigments
C1f - Emulsifiers
New AQA specification Current OCR specification
Specification reference:
5.8.1.3 Chromatography
Specification reference:
C3g
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 Rf values.
N/A
5.8.2 Identification of common gases
New AQA specification Current OCR specification
Specification reference:
5.8.2.1 Test for hydrogen
This topic is not covered in the OCR specification.
Specification reference:
5.8.2.2 Test for oxygen
This topic is not covered in the OCR specification.
Specification reference:
5.8.2.3 Test for carbon dioxide
Specification reference:
C1f
Definition of limewater as an aqueous solution of calcium hydroxide.
N/A
Specification reference:
5.8.2.4 Test for chlorine
Specification reference:
C2h
The content of both specifications is the same.
The OCR specification also includes:
C4d Flame tests
New AQA specification Current OCR specification
C4f Precipitation of metal hydroxides
C4h Testing for halide ions and sulfate ions in the context of water purification and testing
5.9 Chemistry of the atmosphere
5.9.1 The composition and evolution of the Earth's atmosphere
New AQA specification Current OCR specification
Specification reference:
5.9.1.1 The proportions of different gases in the atmosphere
Specification reference:
C1c
The content of both specifications is very similar.
Specification reference:
5.9.1.2 The Earth's early atmosphere
Specification reference:
C1c
The content of both specifications is almost the same.
The specification includes a consideration of how theories about the early atmosphere have changed, and limitations of the evidence. It also includes the presence of nitrogen, methane and ammonia.
A detailed description of atmospheric evolution is required at Higher Tier only.
Specification reference:
5.9.1.3 How oxygen increased
Specification reference:
C1c
The content of both specifications is the same, except that the chemical equation for photosynthesis is included in the AQA specification.
Specification reference:
5.9.1.4 How carbon dioxide decreased
Specification reference:
C1c
5.9.2 Carbon dioxide and methane as greenhouse gases
New AQA specification Current OCR specification
Specification reference:
5.9.2.1 Greenhouse gases
The mechanism of the greenhouse effect in terms of radiation of different wavelengths is not covered in the OCR specification.
Specification reference:
5.9.2.2 Human activities which contribute to an increase of greenhouse gases in the atmosphere
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.
Specification reference:
5.9.2.3 Global climate change
The potential effects of climate change are not covered in the OCR specification.
Specification reference:
5.9.2.4 The carbon footprint and its reduction
This topic is not covered in the OCR specification.
5.9.3 Common atmospheric pollutants and their sources
New AQA specification Current OCR specification
Specification reference:
5.9.3.1 Atmospheric pollutants from fuels
Specification reference:
• C1b
• C1c
The content is very similar in both specifications, covering the formation of carbon dioxide, carbon monoxide, carbon, sulfur dioxide and oxides of nitrogen. Both refer to particulates or soot.
Specification reference:
5.9.3.2 Properties and effects of atmospheric pollutants
Specification reference:
• C1b
• C1c
Much of the content is the same, including carbon monoxide's effect on the blood, and sulfur dioxide and oxides of nitrogen causing acid rain.
The specification also includes the effect of particulates on global dimming. The respiratory effects of particulates, sulfur dioxide and
N/A
New AQA specification Current OCR specification
oxides of nitrogen.
5.10 Using resources
5.10.1 Using the Earth's resources and obtaining potable water
New AQA specification Current OCR specification
Specification reference:
5.10.1.1 Using the Earth's resources and sustainable development
This topic is not covered in the OCR specification. However, ideas regarding the use of chemistry to improve processes can be found in several of the specification's contexts such as C3e Percentage Yield and Atom Economy, and C3g Batch or Continuous.
Similar ideas are covered in both specifications, with both referring to natural and synthetic materials, although the examples are different. The AQA specification refers to finite and renewable resources and to sustainable development, while the OCR specification focuses on the properties of materials, with sustainability developed in other areas throughout the specification.
N/A Also included in the OCR specification are
C2a – the Earth's geology is covered in detail.
C2b - the use of limestone as a building material, including the production of cement and concrete
C2h - the acquisition of salt and the chlor-alkali industry
C3a - the development of pharmaceutical drugs and batch and continuous production processes are covered in detail.
Specification reference:
5.10.1.2 Potable water
Specification reference: C4h
The content of both specifications is very similar, but the AQA
New AQA specification Current OCR specification
specification includes choosing an appropriate water source, filtration, the use of ozone or ultraviolet light for sterilisation, and desalination are all included.
Distillation of salt solution to obtain water is a required practical in the AQA specification.
Specification reference:
5.10.1.3 Waste water treatment
This topic is not covered in the OCR specification.
Specification reference:
5.10.1.4 Alternative methods of extracting metals
Phytomining and bioleaching are not covered in the OCR specification, except for copper extraction mentioned in C2c.
5.10.2 Life cycle assessment and recycling
New AQA specification Current OCR specification
Specification reference:
5.10.2.1 Life cycle assessment
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.
Specification reference:
5.10.2.2 Ways of reducing the use of resources
Specification reference:
• C1e
• C2c to 2d
Both specifications cover recycling of metals and environmental impacts of extracting metals. However, the 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) are considered as well as recycling. As well as metals, the resources considered also include glass, building materials and ceramics. The energy required coming from limited resources is also included.
N/A