Download pdf - GCSE Chemistry from Edexcel Chemistry A Switching to AQA

Switching to AQA from Edexcel: Chemistry A If you’re thinking of switching to AQA from Edexcel Chemistry A (2CH01) 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 current Edexcel specification, with our new specification (8462) for 2016 onwards.

Comparison overview Most of the content is common to both specifications, although the emphasis and style is different. AQA specification has a greater emphasis on the effects of chemistry in our world.

There is flexibility to co-teach the Chemistry and Combined Science: Trilogy (8464) courses.

Assessment New AQA specification Current Edexcel specification

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 externally assessed written papers (1 hour).

• Paper 1 examines unit C1



Controlled assessment is an internal assessment of practical skills.

Content

Practicals

New AQA specification Current Edexcel 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.

Each of the three units includes practical investigations which may be externally examined, as well as further suggestions for practical work. Internally assessed controlled assessment tasks are taken from these investigations.

Working scientifically


Specification reference: WS 1.1 to WS 4.6

Specification reference: How Science Works

'Working scientifically' encompasses all the activities that scientists do. It is woven throughout the specification and written papers. There are cross-references to the relevant skills development opportunities in the subject content.

There is no cross-referencing to Working scientifically skills in the subject content.

Atomic structure and the periodic table

4.1.1 A simple model of the atom, symbols, relative atomic mass, electronic charge and isotopes


Specification reference:

4.1.1.1 Atoms, elements and compounds


• C1 0.1 to 0.3

• C2.13a

• C2 2.5

• C3 0.4

• C3.5

This is a summary of the skills which students will need throughout all topics: using names, symbols and various types of equation. Much of this is spread throughout the current Edexcel specification.


A definition of a compound. Risk assessments for practical work and hazard symbols.


4.1.1.2 Mixtures


C2 3.8 to 3.10

Both specifications include the separation of mixtures by fractional distillation and chromatography.

A definition of a mixture, filtration, distillation and simple distillation.

The separation of two immiscible liquids.


4.1.1.3 Scientific models of the atom


C2 1.3

Both specifications describe the nuclear model of the atom.

Description of the historical development of different models of the atom.

N/A


4.1.1.4 Relative electrical charges of subatomic particles


C2 1.5 to 1.8a

The content is identical in both specifications.


4.1.1.5 Size and mass of atoms


• C2 1.4

• C1.6

• C1.8b

• C1.10

Both specifications describe the relative sizes of the atom and nucleus and the relative masses of the proton, neutron and electron.

The actual sizes of the nucleus and atom.

Isotopes are included for students of all abilities, along with calculation of the number of protons, neutrons and electrons in an atom or ion.

Higher Tier: the treatment of isotopes. The treatment goes further than AQA, looking at the effect of the existence of isotopes on relative atomic mass.



4.1.1.6 Electronic structure


C2 1.12


4.1.2 The periodic table



4.1.2.1 The periodic table


• C2 1.9

• C1.13

• C4.1

The content is almost identical in both specifications.

Prediction of possible reactions and reactivity from position in the periodic table.

N/A


4.1.2.2. The development of the periodic table


C2 1.1

Both specifications describe how Mendeleev developed the periodic table.

Early periodic tables before Mendeleev.

N/A


4.1.2.3 Metals and non-metals


C2 1.2

Both specifications describe the position of metals and non-metals in the periodic table.

The differences between metals and non-metals: ions they form and their characteristic physical and chemical properties.

N/A


4.1.2.4 Group 0


C2 4.14 to 4.17


Both specifications cover the lack of reactivity of the noble gases and the trends in physical properties.

N/A The discovery and uses of the noble gases.


4.1.2.5 Group 1


C2 4.6 to 4.8

The typical physical properties of the alkali metals and their reaction with water.

Low density of the metals, colour and solubility of compounds.

Higher Tier: explanation of the pattern of reactivity.


4.1.2.6 Group 7


C2 4.9 to 4.13

Both specifications cover:

• the reaction of the halogens with metals and non-metals

• displacement reactions of halogens with metal halides leading to the trend in reactivity.

The trend in relative molecular mass, melting point and boiling point and the existence as diatomic molecules.

The reaction of metals includes the formation of ions with a -1 charge. The reaction with non-metals is more general.

Recall of colours and physical states of the halogens at room temperature.

The reaction with non-metals is restricted to the reaction with hydrogen to produce hydrogen halides which form acids in water.

Displacement reactions of halogens is a required practical.

4.1.3 Properties of transition elements



4.1.3.1 Comparison with Group 1 elements


C2 4.4a


Both specifications include a comparison of melting points of transition metals and Group 1 elements.

A comparison of strength and relative reactivity with Group 1 elements. The properties are exemplified by reference to six specified transition metals.

N/A


4.1.3.2 Typical properties


C2 4.4b

Both specifications include the formation of coloured compounds by transition metals.

The formation of ions with different charges and catalytic activity exemplified by reference to six specified transition metals.

N/A

Bonding, structure and the properties of matter

4.2.1 Chemical bonds, ionic, covalent and metallic



4.2.1.1 Chemical bonds


C2 2.1

Introduction to the types of bonding. The detailed content is spread throughout the Edexcel specification, but it’s not summarised in the same way as in the AQA specification.


4.2.1.2 Ionic bonding


C2 2.2 to 2.5

Both specifications deal with ionic bonding as electron transfer, using sodium chloride as an example.

The relation of charge on the ions to the group number.

• the terms cation and anion

• ions as charged groups of atoms

• the endings -ide and -ate in names of compounds.



4.2.1.3 Ionic compounds


C2 2.7 (Higher Tier only)

The description of an ionic compound as a lattice, with strong electrostatic forces, is included in both specifications, but is only for Higher Tier in the Edexcel specification, unlike AQA.

Dot-and-cross, ball-and-stick, and space-filling diagrams, with a consideration of their limitations. Students are expected to deduce that a compound is ionic and to deduce the empirical formula from a diagram.

N/A


4.2.1.4 Covalent bonding


C2 3.1 to 3.3

The description of covalent bonding, as sharing of pairs of electrons, is very similar in both specifications. However, the examples are different, and two of the Edexcel examples are for Higher Tier only.

Both specifications include dot-and-cross diagrams.

Large molecules, such as polymers and giant structures, including silicon dioxide.

The limitations of different types of diagram, including ball-and-stick, 2D and 3D representations. Students are expected to deduce the molecular formula of a substance from a given model or diagram.

N/A


4.2.1.5 Metallic bonding


C2 4.2

The content is almost the same. AQA specification emphasises 2D and 3D representations.

4.2.2 How bonding and structure are related to the properties of substances




4.2.2.1 The three states of matter

N/A

Description of the particle model of the three states of matter and changes of state. It includes the prediction of the state of a substance at different temperatures (given appropriate data).

This topic is not covered, however understanding of most of the ideas is assumed in other areas, such as covalent compounds C2 3.4, 3.5, 3.9 and gases, equilibria and ammonia, C3 4.


4.2.2.2 State symbols


• C1

• C2

• C3 0.3



4.2.2.3 Properties of ionic compounds


• C2 2.7 to 2.8

• C4.5

Both specifications describe and explain the high melting and boiling point and electrical conductivity of ionic substances.

Edexcel Higher Tier: the explanation of the properties.

AQA has the description and the explanation for students of all abilities.


4.2.2.4 Properties of small molecules


• C2 3.5

• C4.5

Both specifications describe and explain the low melting and boiling point and lack of electrical conductivity of substances consisting of small molecules.

Intermolecular forces increase with size of molecules.

N/A


4.2.2.5 Polymers

N/A


The size of the molecules, the strength of bonding and intermolecular forces of polymers linked to their properties as solids at room temperature.

N/A


4.2.2.6 Giant covalent structures


• C2 3.6

• C4.5

Both specifications deal with the difference between simple molecular and giant covalent substances. Both refer to diamond and graphite. AQA specification also includes silicon dioxide.


4.2.2.7 Properties of metals and alloys


• C1 4.10 to 4.11

• C2 4.3

• C4.5

Both specifications use models to explain the difference in properties between pure metals and alloys.

The strength of metallic bonding is linked to most metals having high melting and boiling points.

Edexcel covers here uses of metals in relation to their properties (AQA has this topic in section 4.10.3.2).


4.2.2.8 Metals as conductors


C2 4.3

Both specifications describe and explain electrical conductivity.

AQA describes and explains conduction of thermal energy.

N/A

N/A Section 4.5 classifies elements and compounds as four main structure types, with their properties.

Edexcel also includes relative solubility in water.

There is a required practical investigation of structure type.

4.2.3 Structure and bonding of carbon



4.2.3.1 Diamond


• C2 3.7

• C4.5

The content is almost identical. Edexcel specification includes use of diamond in cutting tools (Higher Tier).


4.2.3.2 Graphite


• C2 3.7

• C4.5


The conduction of thermal energy. Higher Tier: the use of graphite as electrodes and a lubricant.


4.2.3.3 Graphene and fullerenes

N/A

4.2.4 Bulk and surface properties of matter including nanoparticles



4.2.4.1 Sizes of particles and their properties

N/A


4.2.4.2 Uses of nanoparticles

N/A

Quantitative chemistry

4.3.1 Conservation of mass and the quantitative interpretation of chemical equations



4.3.1.1 Conservation of mass and balanced chemical equations


• C1 2.13 b

• C1.2.13c


• C2.16

There is no clear link between conservation of mass and balanced chemical equations in the Edexcel specification.


4.3.1.2 Relative formula mass


C2 6.1

There is no clear link between the sum of the relative formula masses and balanced chemical equations in the Edexcel specification.


4.3.1.3 Mass changes when a reactant or product is a gas

N/A

4.3.2 Uses of amount of substance in relation to masses of pure substances



4.3.2.1 Moles


C3 2.7 to 2.8

Higher Tier content in both specifications.

Avogadro constant and the mole applied to formulae, equations and particles.

N/A


4.3.2.2 Amounts of substances in equations

Specification reference:C2 6.5



4.3.2.3 Using moles to balance equations (Higher Tier only)

N/A


4.3.2.4 Limiting reactants (Higher Tier only)

N/A



4.3.2.5 Concentration of solutions


C3 2.1

Higher Tier: AQA

Students of all abilities: Edexcel.

4.3.3 Yield and atom economy of chemical reactions



4.3.3.1 Percentage yield


C2 6.6 to 6.9

Both specifications require a calculation of percentage yield. They give reasons for a yield being less than 100% (AQA reason is reversible reactions not going to completion).


4.3.3.2 Atom economy

This topic is not covered in the Edexcel specification.

However, in sections C2 6.10 to C6.11 the specification includes an understanding of waste products and their problems and chemists in industry working to find the economically most favourable reactions.

4.3.4 Using concentrations of solutions in mol/dm3



4.3.4 Using concentrations of solutions in mol/dm3


• C3 2.9

• C2.13 to 2.15

Both specifications describe a titration and carry out calculations.

AQA: whole topic is Higher Tier only.

Edexcel: only calculations are Higher Tier; a description of a titration is for students of all abilities.

4.3.5 Use of amount of substance in relation to volumes of gases



4.3.5 Use of amount of substance in relation to volumes of gases


C3 4.1 to 4.3


Calculation of the volume of a gas from its mass and relative formula mass.

Calculations involving balanced equations, masses of solids and volumes of gases.

Chemical changes

4.4.1 Reactivity of metals



4.4.1.1 Metal oxides


C1 4.5

Both specifications define oxidation and reduction as gain and loss of oxygen. Only the AQA specification refers to the reaction of metals with oxygen.


4.4.1.2 The reactivity series

This topic is not covered in the Edexcel specification, although reference is made to the reactivity series in the context of metal extraction in C1 4.3


4.4.1.3 Extraction of metals and reduction


C1 4.1 to 4.6

The emphasis is on carbon reduction and position in the reactivity series. Extraction by electrolysis (aluminium) is included here in the Edexcel specification, but covered in the Electrolysis topic in the AQA specification.

N/A A practical investigation of methods for extracting a metal from its ore.


4.4.1.4 Oxidation and reduction in


C3 3.3


terms of electrons

AQA: Higher Tier only.

Edexcel specification includes this topic only in the context of electrolysis, while AQA includes displacement reactions.

Ionic equations for displacement reactions.

N/A

4.4.2 Reactions of acids



4.4.2.1 Reactions of acids with metals

N/A


4.4.2.2 Neutralisation of acids and salt production


• C1 3.4 to 3.5

• C2 2.6

The content is the same in both specifications.


4.4.2.3 Soluble salts


• C3 2.10 to 11

• C2.14

Both specifications cover the preparation of a soluble salt from an acid and an insoluble starting material.

Crystallisation of solutions to produce solid salts.

There is a required practical to prepare a soluble salt from an insoluble oxide or carbonate.

Preparation of a soluble salt by titration, including a required practical.


4.4.2 4 The pH scale and neutralisation


C3 2.12


Both specifications describe neutralisation as reaction between hydrogen ions and hydroxide ions.

pH scale from 0 to 14, the use of universal indicator and pH probes.

Titration is the required practical.

Sections C1 3.1 to C3.3, cover the production of hydrochloric acid in the stomach and indigestion remedies, including a required practical investigation.


4.4.2.5 Strong and weak acids

N/A

4.4.3 Electrolysis



4.4.3.1 The process of electrolysis


• C3 3.1 to 3.2

• C3.5

Higher Tier in both specifications: Writing half equations.


4.4.3.2 Electrolysis of molten ionic compounds


C3 3.11d

The content is based on lead bromide as an example.

Prediction of the products of electrolysis of molten binary ionic compounds.

N/A


4.4.3.3 Using electrolysis to extract metals


• C1 4.2b

• C3 3.6 to 3.7

The AQA specification includes details of the extraction of aluminium. The Edexcel specification requires only the knowledge of electrolysis use.

N/A The manufacture of sodium and uses of sodium.



4.4.3.4 Electrolysis of aqueous solutions


• C1 3.6 to 3.7

• C3.13

• C3 3.8 to 3.11

The topic is treated differently in the two specifications: AQA focuses on principles and Edexcel on examples.

Rules for which product is produced at each electrode, leading to prediction of the products of electrolysis of aqueous solutions containing a single ionic compound.

There is a required practical investigating the electrolysis of solutions with inert electrodes.

Electrolysis of hydrochloric acid (without explanation of the electrode products), including a required practical.

It also includes:

• the electrolysis of sea water and uses of the products

• the decomposition of water by electrolysis

• the electrolysis of sodium chloride, copper chloride, copper sulfate, sodium sulfate

• a required practical including mass changes of copper electrodes in electrolysis of copper sulfate solution

• the purification of copper using copper electrodes

• electroplating.


4.4.3.5 Representation of reactions at electrodes as half-equations


C3 3.3 to 3.5


Edexcel: only writing half-equations is at Higher Tier. Description of redox in terms of electron transfer is for students of all abilities.

Energy changes

4.5.1 Exothermic and endothermic reactions



4.5.1.1 Energy transfer during exothermic and endothermic reactions


C 5.1 to 5.3

Both specifications include a required practical, although these have different aims and use different examples.

Conservation of energy during reactions. Uses and applications of exothermic and endothermic reactions.

N/A


4.5.1.2 Reaction profiles


C2 5.6

Edexcel: Higher Tier only; the content does not include knowledge of activation energy.


4.5.1.3 The energy change of reactions


• C3 5.4

• C5.5

Both specifications include a description of bond breaking as being endothermic and bond making as exothermic, with the consequent effect on the overall energy change.


Edexcel: students of all abilities.

Calculation of energy transfer from bond energies.

A required practical comparing the temperature rise when the same volume of water is heated by different fuels (C1 5.24).

4.5.2 Chemical cells and fuel cells



4.5.2.1 Cells and batteries

N/A



4.5.2.2 Fuel cells


C1 5.21

The majority of this topic is not covered in the Edexcel specification. It requires knowledge that energy can be provided by a simple hydrogen-oxygen fuel cell.

The rate and extent of chemical change

4.6.1 Rate of reaction



4.6.6.1 Calculating rates of reactions

N/A


4.6.1.2 Factors which affect the rates of chemical reactions


• C2 5.8 to 5.9

• C5.12

The content is very similar in the two specifications. Both include a required practical, although this is restricted to the effect of concentration changes in the AQA specification.

The effect of gas pressure, the idea of surface area to volume ratio for solids and three specific methods for investigating rates.

Knowledge that reaction rates can vary from very fast to very slow.


4.6.1.3 Collision theory and activation energy


C2 5.10 to 5.11

Both specifications deal with the effect of changing the frequency and energy of particle collisions.

AQA: the whole topic is for students of all abilities.

Edexcel: all content is Higher Tier, except the idea that reactions occur when particles collide.


An explanation of the effect of changing temperature, concentration and pressure in terms of collision theory, including the idea of activation energy.

An explanation of the effect on rate of changing size of pieces of solid, in terms of surface area to volume ratio.

The Edexcel specification is less specific.


4.6.1.4 Factors that increase the rate of reaction


C2 5.10 to 5.11

The content is very similar, although the Edexcel specification is less detailed. The AQA specification is for students of all abilities, whereas it is Higher Tier only in the Edexcel specification.

Use of simple ideas about proportionality when using collision theory.

N/A


4.6.1.5 Catalysts


C2 5.12 to 5.13

The AQA specification is much more detailed. Only the recall of the effect of a catalyst on a reaction rate is common to both specifications.

The definition of a catalyst, specificity of catalysts, enzymes as catalysts, an explanation of catalytic action in terms of lowering activation energy and the effect of a catalyst on a reaction profile.

The use of catalytic converters in cars.

4.6.2 Reversible reactions and dynamic equilibrium



4.6.2.1 Reversible reactions


C3 4.6

This brief introduction is common to both specifications. Reference to


the fact that changing conditions alters the position of equilibrium (without any detail) is for students of all abilities in the AQA specification. Edexcel covers this topic in detail at Higher Tier only.


4.6.2.2 Energy changes and reversible reactions


C3 4.8

This topic, using hydrated and anhydrous copper sulfate as an example, is included in the AQA specification for students of all abilities. It is implicit in section 4.8a of the Edexcel specification, but only at Higher Tier.


4.6.2.3 Equilibrium


C3 4.7

This topic is very similar (Higher Tier only in both specifications).

Emphasis of the need for a closed system.

N/A


4.6.2.4 The effect of changing conditions on equilibrium


C3 4.8

Both specifications require knowledge of how conditions affect equilibrium position at Higher Tier. However, only the AQA specification does this in terms of Le Chatelier's principle.


4.6.2.5 The effect of changing concentration (Higher Tier only)

N/A


4.6.2.6 The effect of temperature changes on equilibrium


C3 4.8a



4.6.2.7 The effect of pressure changes on equilibrium


C3 4.8b


Organic chemistry

4.7.1 Carbon compounds as fuels and feedstock



4.7.1.1 Crude oil, hydrocarbons and alkanes


• C1 5.1 to 5.2

• C5.25 to 5.26

• C3 5.9 to 5.10a

The content is very similar, although the general formula for alkanes is only implicit in the Edexcel specification.

The formation of crude oil and recognition of other substances as alkanes from their formula.

The Edexcel specification includes, in section C3 5.9, a definition of a homologous series, which is not explicit in the AQA specification.


4.7.1.2 Fractional distillation and petrochemicals


C1 5.3 to 5.4

The content is very similar in both specifications.

AQA requires explaining fractional distillation, along with an awareness of the vast array of natural and synthetic carbon compounds. There is reference to solvents, lubricants, polymers and detergents as derivatives of crude oil.

Edexcel doesn’t require details of fractional distillation, but asks for uses of different fractions, including bitumen (not mentioned in the AQA specification).


4.7.1.3 Properties of hydrocarbons


C1 5.5 to 5.6

The content is almost identical. Writing balanced equations for combustion reactions is for Higher Tier only in the Edexcel specification. AQA has the whole topic for students of all abilities.


4.7.1.4 Cracking and alkenes


C1 5.29 to 32

The content is very similar. However, the Edexcel specification requires a description of cracking in the laboratory while AQA requires knowledge of the industrial conditions. Writing balanced equations for cracking


reactions is Higher Tier only in the Edexcel specification, unlike AQA where it is for students of all abilities.

Alkenes as starting materials for many other chemicals.

Modern life depending on the uses of hydrocarbons (the Edexcel specification only refers to polymers).

The use of data on the composition of different crude oils and demand for the fractions is required for Higher Tier only.

4.7.2 Reactions of alkenes and alcohols



4.7.2.1 Structure and formulae of alkenes


• C1 5.27 to 5.28

• C3 5.9

• C5.10b

The content is very similar in both specifications. However, the AQA specification covers more alkenes; the general formula for alkenes is only implicit in the Edexcel specification.

Recognition of substances as alkenes from their names or given formulae.

N/A


4.7.2.2 Reactions of alkenes

Specification reference: C3 5.6

The AQA specification requires many more reactions; only the reaction of ethene with steam is common to both. That reaction is Higher Tier at Edexcel, unlike at AQA.

Reactions of alkenes with oxygen (including incomplete combustion), hydrogen and halogens.

N/A


4.7.2.3 Alcohols


• C3 5.1 to 5.9

• C5.10c


• C5.11

Only the names, formulae and structures of alcohols are common to both specifications (but are at Higher Tier only in the Edexcel specification).The AQA specification includes one more alcohol.

Neutral solutions in water, reaction with sodium, combustion, use as fuels and solvents. Recognition of other substances as alcohols from their names or formulae.

A required practical to make ethanol by fermentation and obtaining a concentrated solution of ethanol by fractional distillation of the fermentation mixture (for students of all abilities).

A consideration of the different alcohol content in various drinks, the social issues and possible harmful effects of drinking alcohol. Oxidation of open bottles of wine, production of vinegar.

Higher Tier: evaluation of two different methods of manufacturing ethanol; dehydration of ethanol.


4.7.2.4 Carboxylic acids


• C5 5.

• C5.10d

• C5.12 to 5.14

The names, formulae and structures of carboxylic acids are common to both specifications (but are at Higher Tier only in the Edexcel specification). The AQA specification includes one more acid.

Both specifications also cover reaction with metal carbonates and esterification.

Understanding that acids are weak because of incomplete ionisation in water. Recognition of other substances as carboxylic acids from their names or formulae.

No balanced equations are required in this topic.

The uses of vinegar as flavouring and a preservative. Reactions of ethanoic acid with metals and with bases to form ethanoate salts.

Higher Tier: equation for the formation of ethyl ethanoate using molecular and structural formulae.

4.7.3 Synthetic and naturally occurring polymers



4.7.3.1 Addition polymerisation


C1 5.33 to 5.37

The content is similar in both specifications, although equations are at Higher Tier only in the Edexcel specification, unlike at AQA.

A definition of addition polymerisation.

Poly(chloroethene) and PTFE. Uses of the specified polymers related to their properties.

The problems of disposal of polymers and how they can be overcome.


4.7.3.2 Condensation polymerisation (Higher Tier only)

N/A


4.7.3.3 Amino acids (Higher Tier only)

N/A


4.7.3.4 DNA and other naturally occurring polymers (Higher Tier only)

N/A

Chemical analysis

4.8.1 Purity, formulations and chromatography



4.8.1.1 Pure substances

N/A


4.8.1.2 Formulations

N/A


4.8.1.3 Chromatography


C2 3.10 to 11

The content is similar in both specifications: calculation requirement of Rf values.

An explanation of how chromatography works, including stationary phase and mobile phase. Reference to different solvents.

There is a required practical on chromatography and calculation of Rf values.

The topic is dealt with in the contexts of the food industry and forensic science.

4.8.2 Identification of common gases



4.8.2.1 Test for hydrogen



4.8.2.2 Test for oxygen



4.8.2.3 Test for carbon dioxide



4.8.2.4 Test for chlorine


The content for all four tests is identical in both specifications.

4.8.3 Identification of ions by chemical and spectroscopic means



4.8.3.1 Flame tests

Specification reference: C2 2:15a

The content is almost identical. The AQA specification includes one more metal ion (lithium).


4.8.3.2 Metal hydroxides

Specification reference: C3 1.3a

The content is almost identical. The AQA specification includes one more metal ion (magnesium). The Edexcel section C3 1.3b also gives a test for


ammonium ions, which is not covered in the AQA specification.


4.8.3.3 Carbonates


• C2 2.9e

• C2.15b



4.8.3.4 Halides


• C2 2.15d

• C3 1.3c



4.8.3.5 Sulfates

Specification reference: C2 2.15c



4.8.3.6 Instrumental methods


The AQA specification gives the advantages of instrumental techniques in general. The Edexcel specification only includes flame spectroscopy.


4.8.3.7 Flame emission spectroscopy


Both specifications mention the technique, but with different purposes.

The process is described, along with the production of a spectrum, which students must be able to interpret given appropriate data.

The focus is the use of the technique to detect elements. Use in the discovery of new elements is also mentioned.

Both specifications include a required practical to identify the ions in a single ionic compound.


N/A The Edexcel specification includes:

• understanding of the difference between qualitative and quantitative analysis

• the idea that the test for any ion must be unique

• understanding that these tests can be used to check the purity of drinking water and to detect the presence of substances in the blood.

Chemistry of the atmosphere

4.9.1 The composition and evolution of the Earth's atmosphere



4.9.1.1 The proportions of different gases in the atmosphere


C1 1.7 to 1.9a


N/A A required practical to investigate the proportion of oxygen in the atmosphere.


4.9.1.2 The Earth's early atmosphere


C1 1.1 to 1.5


The presence of nitrogen, methane and ammonia.

N/A


4.9.1.3 How oxygen increased




4.9.1.4 How carbon dioxide decreased



AQA specification refers to the formation of coal, crude oil and limestone. Edexcel specification refers only to limestone.

4.9.2 Carbon dioxide and methane as greenhouse gases



4.9.2.1 Greenhouse gases



The content is similar, but the AQA specification is more detailed, describing the greenhouse effect in terms of the interaction of radiation of different wavelengths with matter.


4.9.2.2 Human activities which contribute to an increase of greenhouse gases in the atmosphere.


• C1 1.9b

• C5.14

• C5.16

The content is very similar, but the AQA specification includes the decomposition of rubbish in landfill sites contributing to an increase in greenhouse gases.


4.9.2.3 Global climate change

N/A


4.9.2.4 The carbon footprint and its reduction


• C1 5.15

• C5.17 to 5.19

• C5.22 to 5.23

The methods of reduction of carbon footprint are different in the two specifications.

A definition of carbon footprint, the ideas of energy conservation, carbon taxes and licenses, carbon off-setting and carbon neutrality, problems of reducing the carbon footprint.

Iron seeding of oceans, biofuels as an alternative to fossil fuels and hydrogen as an alternative to petrol as a fuel in cars.

4.9.3 Common atmospheric pollutants and their sources



4.9.3.1 Atmospheric pollutants from fuels


• C1 5.8

• C5.11

Both specifications deal with the production of carbon, carbon monoxide and sulfur dioxide.


Coal as a fuel, the production of oxides of nitrogen and prediction of the combustion products of a fuel (given appropriate information).

N/A


4.9.3.2 Properties and effects of atmospheric pollutants


C1 5.9 to 5.10 and 5.12

The content is similar in both specifications, although the AQA specification includes more effects.

Respiratory problems caused by sulfur dioxide and oxides of nitrogen, oxides of nitrogen causing acid rain and the effects of particulates.

The context of incomplete combustion in appliances using carbon compounds as fuels.

N/A Factors that make a good fuel (section C1 5.20)

Using resources

4.10.1 Using the Earth's resources and obtaining potable water



4.10.1.1 Using the Earth's resources and sustainable development

There is no equivalent topic in the Edexcel specification, although sections C1 5.18 to 5.23 touch on some of the principles.


4.10.1.2 Potable water

N/A


4.10.1.3 Waste water treatment

N/A


4.10.1.4 Alternative methods of extracting metals

N/A

4.10.2 Life cycle assessment and recycling



4.10.2.1 Life cycle assessment

N/A


4.10.2.2 Ways of reducing the use of resources


C1 4.9

Most of this topic is not covered in the Edexcel specification – it only covers recycling of metals.

4.10.3 Using materials



4.10.3.1 Corrosion and its prevention


C1 4.7 to 4.

Both specifications discuss corrosion of metals.

The conditions needed for rusting and corrosion prevention methods, including corrosion inhibitors and sacrificial protection. The protective oxide layer on aluminium.

The main focus is the relation of a metal's resistance to corrosion to its position in the reactivity series. Prevention of corrosion is not covered.


4.10.3.2 Alloys as useful materials


C1 4.12 to 4.14

Both specifications cover the reasons for alloying metals, steels and alloys of gold including carats (gold is Higher Tier only in the Edexcel specification). Other alloys covered are different.

Alloys of copper and aluminium. Higher Tier: shape memory alloys; the proportion of gold in alloys is indicated by fineness and carats.


4.10.3.3 Ceramics, polymers and composites

N/A

4.10.4 The Haber process and the use of NPK fertilisers



4.10.4.1 The Haber process


C3 4.9 to 4.10

Both specifications refer to the equilibrium reaction for the process, referring back to the principles of equilibrium and the need to produce an acceptable rate in an acceptable time.

Edexcel Higher Tier: whole topic.

AQA Higher Tier: only the application of the principles of equilibrium and the need for compromise conditions.

For students of all abilities:

• the raw materials and their sources

• the precise conditions used in industry

• how the ammonia is removed from the reaction mixture.

N/A


4.10.4.2 Production and uses of NPK fertilisers


C3 4.4 to 4.5

Both specifications refer to the production of fertilisers from ammonia.

The presence of compounds of potassium and phosphorus. It covers mining for potassium salts and phosphate rock, the treatment of phosphate rock and a comparison of the industrial production of fertilisers with laboratory preparations of the same compounds.

Nitrogenous fertilisers only.

The environmental consequences of the overuse of fertilisers.

Edexcel content no longer required

The following topics are not included in the new DfE subject content:

• Specification reference: C1 2.1 to 2.6

Igneous, sedimentary and metamorphic rocks

• Specification reference: C1 2.17 to 2.12, 2.14 to 2.15, 2.17 to 2.18

Limestone, decomposition of metal carbonates, calcium oxide and calcium hydroxide

• Specification reference: C2 2.9 to 2.14

Solubility rules for common types of substance, preparation of insoluble salts by precipitation, uses of barium sulfate

• Edexcel specification reference: C3 2.2 to 2.6

Hard water