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Revision summary help for the 9-1 AQA GCSE CHEMISTRY 2nd Exam Paper 2 learning objectives for AQA GCSE chemistry 8462/2F and 8462/2H chemistry 2 2020 exam paper onwards (re-edit) AQA GCSE (Grade 9-1) Chemistry 8462 Paper 2 chemistry 2 2F 2H papers - AQA Grade 9-1 GCSE CHEMISTRY Topic 6 "The rate and extent of chemical change", Topic 7 "Organic chemistry", Topic 8 "Chemical analysis", Topic 9 "Chemistry of the atmosphere", Topic 10 "Using resources" LINK for AQA 9-1 GCSE CHEMISTRY 1 paper 1 LINK for AQA GCSE Combined Science Trilogy chemistry paper 1 LINK for AQA GCSE Combined Science Trilogy chemistry paper 2 This is a BIG website, you need to take time to explore it [SEARCH BOX] Use your mobile phone 'landscape' orientation? email doc brown - query? or comment? For ALL other exam papers, use and bookmark the link below PLEASE READ CAREFULLY THE FOLLOWING POINTS before using my AQA 9-1 GCSE science pages
Syllabus-specification CONTENT INDEX of revision summary notes for separate science AQA GCSE chemistry Revision summaries for Paper 1 AQA GCSE Chemistry 1 (separate page, science AQA GCSE chemistry) What's assessed in this paper? SUMMARY Topic 1 Atomic structure and the periodic table (AQA 9-1 GCSE Chemistry 1 paper 1) SUMMARY Topic 2 Bonding, structure, and properties of matter (AQA GCSE Chemistry 1 paper 1) SUMMARY Topic 3 Quantitative chemistry (AQA 9-1 GCSE Chemistry 1 paper 1) SUMMARY Topic 4 Chemical changes (AQA 9-1 GCSE Chemistry 1 paper 1) SUMMARY Topic 5 Energy changes (AQA 9-1 GCSE Chemistry 1 paper 1) Revision summaries for Paper 2 AQA GCSE Chemistry 2 (this page, separate science AQA GCSE chemistry)
SUMMARY Topic 6 The rate and extent of chemical change (AQA 9-1 GCSE Chemistry 2 paper 2) Topic 6.2 Reversible reactions and dynamic equilibrium SUMMARY Topic 7 Organic chemistry (AQA 9-1 GCSE Chemistry 2 paper 2) Topic 7.1 Carbon compounds as fuels and feedstock Topic 7.2 Reactions of alkenes and alcohols Topic 7.3 Synthetic and naturally occurring polymers SUMMARY Topic 8 Chemical analysis (AQA 9-1 GCSE Chemistry 2 paper 2) Topic 8.1 Purity, formulations and chromatography Topic 8.2 Identification of common gases Topic 8.3 Identification of ions by chemical and spectroscopic means SUMMARY Topic 9 Chemistry of the atmosphere (AQA 9-1 GCSE Chemistry 2 paper 2) Topic 9.1 The composition and evolution of the Earth's atmosphere Topic 9.2 Carbon dioxide and methane as greenhouse gases Topic 9.3 Common atmospheric pollutants and their sources SUMMARY Topic 10 Using resources (AQA 9-1 GCSE Chemistry 2 paper 2) Topic 10.1 Using the Earth's resources and obtaining potable water Topic 10.2 Life cycle assessment and recycling Topic 10.4 The Haber process and the use of NPK fertilisers
SUBJECT CONTENT of the syllabus-specification: TOPICS for Paper 2 AQA GCSE Chemistry 2 A page of important ideas, concepts and definitions for chemistry students Topic 6 The rate and extent of chemical change Appreciate that chemical reactions can occur at vastly different rates. Whilst the reactivity of chemicals is a significant factor in how fast chemical reactions proceed, there are many variables that can be manipulated in order to speed them up or slow them down. Chemical reactions may also be reversible and therefore the effect of different variables needs to be established in order to identify how to maximise the yield of desired product. Understanding energy changes that accompany chemical reactions is important for this process. In industry, chemists and chemical engineers determine the effect of different variables on reaction rate and yield of product. Whilst there may be compromises to be made, they carry out optimisation processes to ensure that enough product is produced within a sufficient time, and in an energy efficient way. AQA GCSE (Grade 9-1) GCSE chemistry Topic 6 The rate and extent of chemical change quiz content: Factors affecting the rate of a chemical reaction - temperature, concentration, particle size, catalysts etc., reversible reactions, chemical equilibrium, effect of changes in conditions on the position of an equilibrium (HT only)
HT = higher tier (harder - usually more theory & depth) and FT = foundation tier (easier) 6.1 Rate of reaction (AQA GCSE Chemistry 2, paper 2, Topic 6 "The rate and extent of chemical change") 6.1.1 Calculating rates of reactions Know the rate of a chemical reaction can be found by measuring the quantity of a reactant used or the quantity of product formed over time:
The quantity of reactant or product can be measured by the mass in grams or by a volume in cm3. The units of rate of reaction may be given as g/s or cm3/s. For the Higher Tier, you are also required to use quantity of reactants in terms of moles and units for rate of reaction in mol/s. You should be able to:
In the context of rates of reaction data, you must be able to
What do we mean by the rate/speed of reaction? how can we measure it? Revision Notes Examples of graphs of rate data, interpretation Revision Notes 6.1.2 Factors which affect the rates of chemical reactions (AQA GCSE Chemistry 2, paper 2, Topic 6 "The rate and extent of chemical change") Factors which affect the rates of chemical reactions include:
You should be able to recall how changing these factors affects the rate of chemical reactions. Required practical 5: You should have investigated how changes in concentration affect the rates of reactions by a method involving measuring the volume of a gas produced and a method involving a change in colour or turbidity ('cloudiness'!). Particle model of the collision theory of chemical reaction rate factors Revision Notes Effect of changing reactant concentration in solution Revision Notes Effect of changing pressure in reacting gases Revision Notes Effect of changing particle size/surface area & stirring of a solid reactant Revision Notes Effect of changing the temperature of reactants Revision Notes Effect of using a catalyst in a chemical reaction Revision Notes Multiple choice Quiz on the Rates of Chemical Reactions Crossword on Rates of Reactions * Answers Wordfill worksheet on Rates of Chemical Reactions (1) matching pair quizzes on Rates of Chemical Reactions and (2) 2nd Word-fill quiz "What factors Affect the Speed of a Chemical reaction?" 6.1.3 Collision theory and activation energy (AQA GCSE Chemistry 2, paper 2, Topic 6 "The rate and extent of chemical change") You should understand that collision theory explains how various factors affect rates of reactions. According to this theory, chemical reactions can occur only when reacting particles collide with each other and with sufficient energy. The minimum amount of energy that particles must have to react is called the activation energy. Know that increasing the concentration of reactants in solution, the pressure of reacting gases, and the surface area of solid reactants increases the frequency of collisions and so increases the rate of reaction. Increasing the temperature increases the frequency of collisions and makes the collisions more energetic, and so increases the rate of reaction. You should be able to:
Particle model of the collision theory of chemical reaction rate factors Revision Notes Activation energy and reaction profiles Revision Notes 6.1.4 Catalysts (AQA GCSE Chemistry 2, paper 2, Topic 6 "The rate and extent of chemical change") Know that catalysts change the rate of chemical reactions but are not used up during the reaction. Different reactions need different catalysts. Enzymes act as catalysts in biological systems. Catalysts increase the rate of reaction by providing a different pathway for the reaction that has a lower activation energy. Know how to draw a reaction profile for a catalysed reaction. You should be able to identify catalysts in reactions from their effect on the rate of reaction and because they are not included in the chemical equation for the reaction. You should be able to explain catalytic action in terms of activation energy. You do not need to know the names of catalysts other than those specified in the subject content. Effect of using a catalyst in a chemical reaction Revision Notes Activation energy and reaction profiles, catalysts and activation energy Revision Notes Index of topics for AQA GCSE Chemistry paper 1 and paper 2
6.2 Reversible reactions and dynamic equilibrium (AQA GCSE Chemistry paper 2, Topic 6 "The rate and extent of chemical change")
6.2.1 Reversible reactions Know that in some chemical reactions, the products of the reaction can react to produce the original reactants. Such reactions are called reversible reactions and
are represented: A + B
The direction of reversible reactions can be changed by changing the conditions eg + heat 
ammonia + hydrogen chloride
NH4Cl(s)
Reversible Reactions Revision Notes 6.2.2 Energy changes and reversible reactions (AQA GCSE Chemistry 2, paper 2, Topic 6 "The rate and extent of chemical change") Know that if a reversible reaction is exothermic in one direction, it is endothermic in the opposite direction. The same amount of energy is transferred in each case. For example:
Reversible Reactions - experiments described and explained Revision Notes 6.2.3 Equilibrium Understand and know that when a reversible reaction occurs in apparatus which prevents the escape of reactants and products, equilibrium is reached when the forward and reverse reactions occur at exactly the same rate. 6.2.4 The effect of changing conditions on equilibrium (HT only) (AQA GCSE Chemistry 2, paper 2, Topic 6 "The rate and extent of chemical change") Know that the relative amounts of all the reactants and products at equilibrium depend on the conditions of the reaction. If a system is at equilibrium and a change is made to any of the conditions, then the system responds to counteract the change. The effects of changing conditions on a system at equilibrium can be predicted using Le Chatelier’s Principle. You should be able to make qualitative predictions about the effect of changes on systems at equilibrium when given appropriate information. Reversible Reactions - experiments described and explained Revision Notes Reversible reactions and chemical equilibrium (including Le Chatelier's Principle rules) Revision Notes 6.2.5 The effect of changing concentration (HT only) (AQA GCSE Chemistry 2, paper 2, Topic 6 "The rate and extent of chemical change") Know that if the concentration of one of the reactants or products is changed, the system is no longer at equilibrium and the concentrations of all the substances will change until equilibrium is reached again. If the concentration of a reactant is increased, more products will be formed until equilibrium is reached again. If the concentration of a product is decreased, more reactants will react until equilibrium is reached again. You should be able to interpret appropriate given data to predict the effect of a change in concentration of a reactant or product on given reactions at equilibrium. Reversible reactions and chemical equilibrium (including Le Chatelier's Principle rules) Revision Notes 6.2.6 The effect of temperature changes on equilibrium (HT only) (AQA GCSE Chemistry 2, paper 2, Topic 6 "The rate and extent of chemical change") If the temperature of a system at equilibrium is increased:
If the temperature of a system at equilibrium is decreased:
You should be able to interpret appropriate given data to predict the effect of a change in temperature on given reactions at equilibrium. Reversible reactions and chemical equilibrium (including Le Chatelier's Principle rules) Revision Notes 6.2.7 The effect of pressure changes on equilibrium (AQA GCSE chemistry HT only) (AQA GCSE Chemistry 2, paper 2, Topic 6 "The rate and extent of chemical change") Know that for a gaseous reactions at equilibrium:
You should be able to interpret appropriate given data to predict the effect of pressure changes on given reactions at equilibrium. Reversible reactions and chemical equilibrium (including Le Chatelier's Principle rules) Revision Notes NEW QUIZ Combined QUIZ on rates of reaction, reversible reactions and equilibrium - Le Chatelier's Rules Index of topics for AQA GCSE Chemistry paper 1 and paper 2
Topic 7 Organic chemistry (GCSE chemistry HT only) (AQA GCSE Chemistry 2, paper 2, Topic 7 "Organic Chemistry") Appreciate that the chemistry of carbon compounds is so important that it forms a separate branch of chemistry. A great variety of carbon compounds is possible because carbon atoms can form chains and rings linked by C-C bonds. This branch of chemistry gets its name from the fact that the main sources of organic compounds are living, or once-living materials from plants and animals. These sources include fossil fuels which are a major source of feedstock for the petrochemical industry. Chemists are able to take organic molecules and modify them in many ways to make new and useful materials such as polymers, pharmaceuticals, perfumes and flavourings, dyes and detergents. AQA GCSE (Grade 9-1) GCSE chemistry Topic 7 Organic chemistry quiz content: oil, fractional distillation, properties and uses of hydrocarbons, alkanes, cracking and alkenes, structure and reactions of alkenes, alcohols, carboxylic acids, addition polymerisation (HT only), condensation polymerisation (HT only), amino acids (HT only), need Qs on DNA
HT = higher tier (harder - usually more theory & depth) and FT = foundation tier (easier) 7.1 Carbon compounds as fuels and feedstock (AQA GCSE Chemistry 2, paper 2, Topic 7 "Organic Chemistry") Multiple choice QUIZ on Oil Products - hydrocarbon chemistry (best done when 7.1.1 to 7.2.2 completed) Notes 7.1.1 Crude oil, hydrocarbons and alkanes (AQA GCSE Chemistry 2, paper 2, Topic 7 "Organic Chemistry") Know that crude oil is a finite resource found in rocks. Crude oil is the remains of an ancient biomass consisting mainly of plankton that was buried in mud. Crude oil is a mixture of a very large number of
compounds. Most of the compounds in crude oil
are hydrocarbons, which are molecules made up
of hydrogen and carbon atoms only.
Most of the hydrocarbons in crude oil are
hydrocarbons called alkanes. The general
formula for the homologous series of alkanes is
CnH2n+2
The first four members of the alkanes are
methane, ethane, propane and butane.
Alkane molecules can be represented in the
following forms:
C2H6 or
You should be able to recognise substances as alkanes given their formulae in these forms. You do not need to know the names of specific alkanes other than methane, ethane, propane and butane. Alkanes - saturated hydrocarbons, structure and reactions including combustion Revision Notes Fractional distillation of crude oil & molecular properties related to uses of fractions Revision Notes 7.1.2 Fractional distillation and petrochemicals (AQA GCSE Chemistry 2, paper 2, Topic 7 "Organic Chemistry") Know the many hydrocarbons in crude oil may be separated into fractions, each of which contains molecules with a similar number of carbon atoms, by evaporating the oil and allowing it to condense at different temperatures. This process is called fractional distillation. The fractions can be processed to produce fuels and feedstock for the petrochemical industry. Many of the fuels on which we depend for our modern lifestyle, such as petrol, diesel oil, kerosene, heavy fuel oil and liquefied petroleum gases, are produced from crude oil. Many useful materials on which modern life depends are produced by the petrochemical industry, such as solvents, lubricants, polymers, detergents. The vast array of natural and synthetic carbon compounds occur due to the ability of carbon atoms to form families of similar compounds. You should be able to explain the separation of crude oil by fractional distillation. Knowledge of the names of other specific fractions or fuels is not required. Fractional distillation of crude oil & uses of fractions Revision Notes multiple choice QUIZ on Oil Products 3 linked easy Oil Products gap-fill quiz worksheets Word-fill quiz "Origin of Crude Oil" * Word-fill quiz "Crude Oil and its Fractional distillation" Word-fill quiz "Getting products from crude oil" Word-fill quiz "The Uses of the Fractions from Crude Oil" 7.1.3 Properties of hydrocarbons (AQA GCSE Chemistry 2, paper 2, Topic 7 "Organic Chemistry") Know that some properties of hydrocarbons depend on the size of their molecules, including boiling point and viscosity which increase with increasing molecular size and flammability which decreases with increasing molecular size. These properties influence how hydrocarbons are used as fuels. Knowledge of trends in properties of hydrocarbons is limited to: boiling points, viscosity and flammability.
The combustion of hydrocarbon fuels releases energy. During combustion, the carbon and hydrogen in the fuels are oxidised. The complete combustion of a hydrocarbon produces carbon dioxide and water. You should be able to write balanced equations for the complete combustion of hydrocarbons with a given formula. Alkanes - saturated hydrocarbons, structure and reactions including combustion Revision Notes Alkenes - unsaturated hydrocarbons, physical and chemical properties multiple choice QUIZ on Oil Products Word-fill quiz "More on hydrocarbon molecules" 7.1.4 Cracking and alkenes (AQA GCSE Chemistry 2, paper 2, Topic 7 "Organic Chemistry") Know that hydrocarbons can be broken down (cracked) to produce smaller, more useful molecules. Cracking can be done by various methods including catalytic cracking and steam cracking. You should be able to describe in general terms the conditions used for catalytic cracking and steam cracking. The products of cracking include alkanes and another type of hydrocarbon called alkenes. Alkenes are more reactive than alkanes and react with bromine water, which is used as a test for alkenes. You should be able to recall the colour change when bromine water reacts with an alkene. There is a high demand for fuels with small molecules and so some of the products of cracking are useful as fuels. Alkenes are used to produce polymers and as starting materials for the production of many other chemicals. You should be able to balance chemical equations as examples of cracking given the formulae of the reactants and products. You should be able to give examples to illustrate the usefulness of cracking and also be able to explain how modern life depends on the uses of hydrocarbons. Alkenes - unsaturated hydrocarbons - structure and reactions Revision Notes Cracking - a problem of supply and demand, other products Revision Notes multiple choice QUIZ on Oil Products Word-fill quiz "Cracking Oil to make Alkanes and Alkenes" Word-fill quiz "Cracking oil fractions and uses of products" Word-fill quiz "Cracking, fuels and polymers" Word-fill quiz "More on uses of products from cracking" Index of topics for AQA GCSE Chemistry paper 1 and paper 2
7.2 Reactions of alkenes and alcohols (AQA GCSE Chemistry 2, paper 2, Topic 7 "Organic Chemistry")
7.2.1 Structure and formulae of alkenes Know that alkenes are hydrocarbons with a double carbon = carbon bond. The general formula for the homologous series of alkenes is CnH2n Alkene molecules are unsaturated because they contain two fewer hydrogen atoms than the alkane with the same number of carbon atoms. The first four members of the homologous series of alkenes are ethene, propene, butene and pentene. Alkene molecules can be represented in the
following forms:
C3H6
or
You do not need to know the names of individual alkenes other than ethene, propene, butene and pentene. Be able to recognise substances that are alkenes from their names or from given formulae in these forms. Be able to visualise and represent 2D and 3D forms including two dimensional representations of 3D objects. Alkenes - unsaturated hydrocarbons - structure and reactions Revision Notes multiple choice QUIZ on Oil Products 7.2.2 Reactions of alkenes (AQA GCSE Chemistry 2, paper 2, Topic 7 "Organic Chemistry") Know that alkenes are hydrocarbons with the functional group C=C. It is the generality of reactions of functional groups that determine the reactions of organic compounds. Alkenes react with oxygen in combustion reactions in the same way as other hydrocarbons, but they tend to burn in air with smoky flames because of incomplete combustion. Alkenes react with hydrogen, water and the halogens, by the addition of atoms across the carbon-carbon double bond so that the double bond becomes a single carbon-carbon bond. The addition of hydrogen to an alkene (unsaturated) takes place in the presence of a catalyst to produce the corresponding alkane (saturated). The addition of water to an alkene takes place by reaction with steam in the presence of a catalyst to produce an alcohol. Addition of a halogen to an alkene produces a saturated compound with two halogen atoms in the molecule, for example ethene reacts with bromine to produce dibromoethane. You should be able to:
Alkenes - unsaturated hydrocarbons - structure and reactions Revision Notes multiple choice QUIZ on Oil Products Word-fill quiz "Examples of alkanes and alkenes and a test for alkenes" 7.2.3 Alcohols (AQA GCSE Chemistry 2, paper 2, Topic 7 "Organic Chemistry") Know that alcohols contain the functional group –OH. Methanol, ethanol, propanol and butanol are the first four members of a homologous series of alcohols. Alcohols can be represented in the following
forms:
CH3CH2OH
or
Methanol, ethanol, propanol and butanol: You should be able to:
Students do not need to know the names of individual alcohols other than methanol, ethanol, propanol and butanol. You are not expected to write balanced chemical equations for the reactions of alcohols other than for combustion reactions. Alcohols - structures including ethanol - manufacture, properties and reactions Revision Notes Biofuels including gashol Revision Notes Preparing an esters, structure and uses Revision Notes Multiple choice QUIZ on other aspects of Organic Chemistry Word-fill quiz "Making Alcohol and Uses of Alcohol" 7.2.4 Carboxylic acids (AQA GCSE Chemistry 2, paper 2, Topic 7 "Organic Chemistry") Know that carboxylic acids have the functional group –COOH. The first four members of a homologous series of carboxylic acids are methanoic acid, ethanoic acid, propanoic acid and butanoic acid. The structures of carboxylic acids can be
represented in the following forms:
CH3COOH
or
You should be able to:
You do not need to know the names of individual carboxylic acids other than methanoic acid, ethanoic acid, propanoic acid and butanoic acid. You are not expected to write balanced chemical equations for the reactions of carboxylic acids. You do not need to know the names of esters other than ethyl ethanoate. Carboxylic acids and esters, structure and reactions Revision Notes Preparing an esters, structure and uses Revision Notes Multiple choice QUIZ on other aspects of Organic Chemistry Index of topics for AQA GCSE Chemistry paper 1 and paper 2
7.3 Synthetic and naturally occurring polymers (AQA GCSE Chemistry 2, paper 2, Topic 7 "Organic Chemistry")
7.3.1 Addition polymerisation Know that alkenes can be used to make polymers such as poly(ethene) and poly(propene) by addition polymerisation. In addition polymerisation reactions, many small molecules (monomers) join together to form very large molecules (polymers). For example:
In addition polymers the repeating unit has the same atoms as the monomer because no other molecule is formed in the reaction. You should be able to:
Addition polymers - plastics, structure, manufacture and uses Revision Notes More on the uses of plastics, issues with using plastics, solutions and recycling methods Multiple choice QUIZ on Oil Products - hydrocarbon chemistry Multiple choice QUIZ on other aspects of Organic Chemistry Word-fill quiz "Introduction to Polymers and Plastics" Word-fill quiz "Making and using polymers"
Know that condensation polymerisation involves monomers with two functional groups (can be the same or different). When these types of monomers react they join together, usually losing small molecules such as water, and so the reactions are called condensation reactions. The simplest polymers are produced from two different monomers with two of the same functional groups on each monomer. For example: ethanediol and hexanedioic acid polymerise to produce a polyester (diagram on right). You should be able to explain the basic principles of condensation polymerisation by reference to the functional groups in the monomers and the repeating units in the polymers. Be able to visualise and represent 2D and 3D forms including two dimensional representations of 3D objects. Comparing addition polymers and condensation polymers Revision Notes Multiple choice QUIZ on other aspects of Organic Chemistry Revision Notes 7.3.3 Amino acids (HT only) (AQA GCSE Chemistry 2, paper 2, Topic 7 "Organic Chemistry") Know that amino acids have two different functional groups in a molecule. Amino acids react by condensation polymerisation to produce polypeptides. For example: glycine is H2NCH2COOH and polymerises to produce the polypeptide (-HNCH2COO-)n and n H2O Different amino acids can be combined in the same chain to produce proteins. Amino acids and proteins/polypeptides Revision Notes Multiple choice QUIZ on other aspects of Organic Chemistry 7.3.4 DNA (deoxyribonucleic acid) and other naturally occurring polymers (AQA GCSE Chemistry 2, paper 2, Topic 7 "Organic Chemistry") Know that DNA (deoxyribonucleic acid) is a large molecule essential for life. DNA encodes genetic instructions for the development and functioning of living organisms and viruses. Most DNA molecules are two polymer chains, made from four different monomers called nucleotides, in the form of a double helix. Other naturally occurring polymers important for life include proteins, starch and cellulose. Proteins are polymers of amino acids. Starch and cellulose are polymers of sugars. Sugars, starch and cellulose are carbohydrates. You should be able to name the types of monomers from which these naturally occurring polymers are made. Amino acids and proteins/polypeptides Revision Notes Natural Molecules - carbohydrates - sugars - natural polymers - starch and DNA Revision Notes Index of topics for AQA GCSE Chemistry paper 1 and paper 2
Topic 8 Chemical analysis (AQA GCSE Chemistry 2, paper 2, Topic 8 "Chemical analysis") Appreciate that analysts have developed a range of qualitative tests to detect specific chemicals. The tests are based on reactions that produce a gas with distinctive properties, or a colour change or an insoluble solid that appears as a precipitate. Instrumental methods provide fast, sensitive and accurate means of analysing chemicals, and are particularly useful when the amount of chemical being analysed is small. Forensic scientists and drug control scientists rely on such instrumental methods in their work. AQA GCSE (Grade 9-1) GCSE Chemistry 2 Topic 8 Chemical analysis quiz content: identifying common gases, testing for positive ions (cations), testing for negative ions (anions), flame tests, metal hydroxides, carbonates, halides, sulfates, need questions on purity, formulations, flame emission spectroscopy, chromatography, instrumental methods of analysis
HT = higher tier (harder - usually more theory & depth) and FT = foundation tier (easier) 8.1 Purity, formulations and chromatography 8.1.1 Pure substances (AQA GCSE Chemistry 2, paper 2, Topic 7 "Organic Chemistry") Know that in chemistry, a pure substance is a single element or compound, not mixed with any other substance. Pure elements and compounds melt and boil at specific temperatures. Melting point and boiling point data can be used to distinguish pure substances from mixtures. In everyday language, a pure substance can mean a substance that has had nothing added to it, so it is unadulterated and in its natural state, eg pure milk. You should be able to use melting point and boiling point data to distinguish pure from impure substances. Definitions in Chemistry eg atom, molecule, formula, element, compound, mixture, pure, impure - criteria tests Notes 8.1.2 Formulations (AQA GCSE Chemistry 2, paper 2, Topic 7 "Organic Chemistry") A formulation is a mixture that has been designed as a useful product. Many products are complex mixtures in which each chemical has a particular purpose. Formulations are made by mixing the components in carefully measured quantities to ensure that the product has the required properties. Formulations include fuels, cleaning agents, paints, medicines, alloys, fertilisers and foods. You should be able to identify formulations given appropriate information but you do not need to know the names of components in proprietary products. Introduction to formulations and examples explained Revision Notes 8.1.3 Chromatography (AQA GCSE Chemistry 2, paper 2, Topic 7 "Organic Chemistry") Know that chromatography can be used to separate mixtures and can give information to help identify substances. Chromatography involves a stationary phase and a mobile phase. Separation depends on the distribution of substances between the phases. In paper chromatography a solvent moves through the paper carrying different compounds different distances, depending on their attraction for the paper and the solvent. The ratio of the distance moved by a compound (centre of spot from origin) to the distance moved by the solvent can be expressed as its Rf value:
Different compounds have different Rf values in different solvents, which can be used to help identify the compounds. The compounds in a mixture may separate into different spots depending on the solvent but a pure compound will produce a single spot in all solvents. In the context of chromatography, be able to:
Be able to:
Required practical 6: You should have investigated how paper chromatography can be used to separate and tell the difference between coloured substances and calculated Rf values. Paper chromatography Revision Notes Index of topics for AQA GCSE Chemistry paper 1 and paper 2
8.2 Identification of common gases (AQA GCSE Chemistry 2, paper 2, Topic 7 "Organic Chemistry")
Test for hydrogen The test for hydrogen uses a burning splint held at the open end of a test tube of the gas. Hydrogen burns rapidly with a pop sound. Test for oxygen The test for oxygen uses a glowing splint inserted into a test tube of the gas. The splint relights in oxygen. Test for carbon dioxide The test for carbon dioxide uses an aqueous solution of calcium hydroxide (lime water). When carbon dioxide is shaken with or bubbled through limewater the limewater turns milky (cloudy). Test for chlorine The test for chlorine uses litmus paper. When damp litmus paper is put into chlorine gas the litmus paper is bleached and turns white. Summary of 'GCSE' tests for gases and ions Revision Notes Quiz on Qualitative Analysis - chemical test methods and deductions from results 8.3 Identification of ions by chemical and spectroscopic means (AQA 9-1 GCSE Chemistry 2 paper 2)
8.3.1 Flame tests (AQA GCSE Chemistry 2, paper 2, Topic 8 "Identification of ions by chemical and spectroscopic means") Flame tests can be used to identify some metal ions (cations). Lithium, sodium, potassium, calcium and copper compounds produce distinctive colours in flame tests:
If a sample containing a mixture of ions is used some flame colours can be masked. You should be able to identify species from the results of the tests above but flame colours of other metal ions are not required knowledge. Summary of 'GCSE' tests for metal ions Revision Notes Instrumental Methods of Chemical Analysis - section on flame emission spectroscopy Revision Notes Quiz on Qualitative Analysis - chemical test methods and deductions from results 8.3.2 Metal hydroxides (AQA GCSE Chemistry 2, paper 2, Topic 8 "Identification of ions by chemical and spectroscopic means") Know that sodium hydroxide solution can be used to identify some metal ions (cations). Solutions of aluminium, calcium and magnesium ions form white precipitates when sodium hydroxide solution is added but only the aluminium hydroxide precipitate dissolves in excess sodium hydroxide solution. Solutions of copper(II), iron(II) and iron(III) ions form coloured precipitates when sodium hydroxide solution is added.
You should be able to write balanced equations for the reactions to produce the insoluble hydroxides, but you are not expected to write equations for the production of sodium aluminate. Summary of tests for metal ions including equations Revision Notes Transition metal ion chemistry Revision Notes Quiz on Qualitative Analysis - chemical test methods and deductions from results 8.3.3 Carbonates (AQA GCSE Chemistry 2, paper 2, Topic 8 "Identification of ions by chemical and spectroscopic means") Know that carbonates react with dilute acids to form carbon dioxide gas. Carbon dioxide can be identified with limewater. Summary of tests for gases and ions including equations Revision Notes Reactions of acids with carbonates Revision Notes Quiz on Qualitative Analysis - chemical test methods and deductions from results 8.3.4 Halides (AQA GCSE Chemistry 2, paper 2, Topic 7 "Organic Chemistry") Know that halide ions in solution produce precipitates with silver nitrate solution in the presence of dilute nitric acid. Silver chloride is white, silver bromide is cream and silver iodide is yellow. Summary of tests for halide ions including equations Revision Notes Quiz on Qualitative Analysis - chemical test methods and deductions from results 8.3.5 Sulfates (AQA GCSE Chemistry 2, paper 2, Topic 8 "Identification of ions by chemical and spectroscopic means") Know that sulfate ions in solution produce a white precipitate with barium chloride solution in the presence of dilute hydrochloric acid. Required practical 7: You should have used chemical tests to identify the ions in unknown single ionic compounds covering the ions from sections from flame tests to Sulfates (8.3.1 to 8.3.5). Summary of tests for ions including equations Revision Notes Quiz on Qualitative Analysis - chemical test methods and deductions from results 8.3.6 Instrumental methods (AQA GCSE Chemistry 2, paper 2, Topic 8 "Identification of ions by chemical and spectroscopic means") Know that elements and compounds can be detected and identified using instrumental methods. Instrumental methods are accurate, sensitive and rapid and are particularly useful when the amount of a sample is very small. You should be able to state advantages of instrumental methods compared with the chemical tests in this specification. Instrumental Methods of Chemical Analysis e.g. flame emission spectroscopy & gas chromatography Notes Quiz on Qualitative Analysis - chemical test methods and deductions from results 8.3.7 Flame emission spectroscopy (AQA GCSE Chemistry 2, paper 2, Topic 8 "Identification of ions by chemical and spectroscopic means") Know that flame emission spectroscopy is an example of an instrumental method used to analyse metal ions in solutions. The sample is put into a flame and the light given out is passed through a spectroscope. The output is a line spectrum that can be analysed to identify the metal ions in the solution and measure their concentrations. Again, you should be aware of the advantages of instrumental methods compared with the chemical tests in this specification. You should be able to interpret an instrumental result given appropriate data in chart or tabular form, when accompanied by a reference set in the same form, limited to flame emission spectroscopy. Summary of tests for metals ions - flames colours - emission spectroscopy Instrumental Methods of Chemical Analysis including flame emission spectroscopy Quiz on Qualitative Analysis - chemical test methods and deductions from results Index of topics for AQA GCSE Chemistry paper 1 and paper 2
Topic 9 Chemistry of the atmosphere (AQA GCSE Chemistry 2, paper 2, Topic 9 "Chemistry of the atmosphere") The Earth’s atmosphere is dynamic and forever changing. The causes of these changes are sometimes man-made and sometimes part of many natural cycles. Scientists use very complex software to predict weather and climate change as there are many variables that can influence this. The problems caused by increased levels of air pollutants require scientists and engineers to develop solutions that help to reduce the impact of human activity. HT = higher tier (harder - usually more theory & depth) and FT = foundation tier (easier) 9.1 The composition and evolution of the Earth's atmosphere (AQA 9-1 GCSE Chemistry 2 paper 2) 9.1.1 The proportions of different gases in the atmosphere (AQA GCSE Chemistry paper 2, Topic 9 "Chemistry of the atmosphere") Know that for 200 million years, the proportions of different gases in the atmosphere have been much the same as they are today: about four-fifths (approximately 80%) nitrogen, about one-fifth (approximately 20%) oxygen and small proportions of various other gases, including carbon dioxide, water vapour and noble gases. Be able to use ratios, fractions and percentages. Our atmosphere - composition, determining % oxygen, uses of gases in air Revision Notes Word-fill quiz "The Earth's Atmosphere" Word-fill quiz "The Composition of the Earth's Atmosphere" Word-fill quiz "The Evolution of the Earth's Atmosphere" Word-fill quiz "More on the formation of the Earth's atmosphere" Word-fill quiz "Later developments of the Earth's atmosphere" 9.1.2 The Earth's early atmosphere (AQA GCSE Chemistry 2, paper 2, Topic 9 "Chemistry of the atmosphere") Appreciate that the theories about what was in the Earth’s early atmosphere and how the atmosphere was formed have changed and developed over time. Evidence for the early atmosphere is limited because of the time scale of 4.6 billion years. One theory suggests that during the first billion years of the Earth’s existence there was intense volcanic activity that released gases that formed the early atmosphere and water vapour that condensed to form the oceans. At the start of this period the Earth’s atmosphere may have been like the atmospheres of Mars and Venus today, consisting of mainly carbon dioxide with little or no oxygen gas. Volcanoes also produced nitrogen which gradually built up in the atmosphere and there may have been small proportions of methane and ammonia. When the oceans formed carbon dioxide dissolved in the water and carbonates were precipitated producing sediments, reducing the amount of carbon dioxide in the atmosphere. No knowledge of other theories is required but you should be able to, given appropriate information, interpret evidence and evaluate different theories about the Earth’s early atmosphere. Recycling of gases - carbon cycle, global warming, oxygen balance and photosynthesis Revision Notes Past ancient atmospheres, changes due to man's activities Revision Notes Evolution of atmosphere - changes over billions of years, origin of life Revision Notes 9.1.3 How oxygen increased (AQA GCSE Chemistry 2, paper 2, Topic 9 "Chemistry of the atmosphere") Know that algae and plants produced the oxygen that is now in the atmosphere by photosynthesis, which can be represented by the equation:
Algae first produced oxygen about 2.7 billion years ago and soon after this oxygen appeared in the atmosphere. Over the next billion years plants evolved and the percentage of oxygen gradually increased to a level that enabled animals to evolve. Evolution of atmosphere - changes over billions of years, origin of life Revision Notes 9.1.4 How carbon dioxide decreased (AQA GCSE Chemistry 2, paper 2, Topic 9 "Chemistry of the atmosphere") Know that algae and plants decreased the percentage of carbon dioxide in the atmosphere by photosynthesis. Carbon dioxide was also decreased by the formation of sedimentary rocks and fossil fuels that contain carbon. Limestone is a sedimentary rock, mainly calcium carbonate, formed from the shells and skeletons of marine organisms. Coal is a sedimentary rock formed from thick plant deposits that were buried and compressed over millions of years. The remains of plankton were deposited in muds on the sea floor and were covered over and compressed over millions of years, producing crude oil and natural gas that became trapped in the rocks. You should be able to describe the main changes in the atmosphere over time and some of the likely causes of these changes. Evolution of atmosphere - changes over billions of years, origin of life Revision Notes Index of topics for AQA GCSE Chemistry paper 1 and paper 2
9.2 Carbon dioxide and methane as greenhouse gases Greenhouse effect, global warming, climate change, carbon footprint from fossil fuel burning Revision Notes 9.2.1 Greenhouse gases (AQA GCSE Chemistry 2, paper 2, Topic 9 "Chemistry of the atmosphere") Know that greenhouse gases in the atmosphere maintain temperatures on Earth high enough to support life. They allow short wavelength radiation to pass through the atmosphere to the Earth’s surface but absorb the outgoing long wavelength radiation from the Earth causing an increase in temperature. Water vapour, carbon dioxide and methane are greenhouse gases. You should be able to describe the greenhouse effect in terms of the interaction of radiation with matter. Greenhouse effect, global warming, climate change, carbon footprint from fossil fuel burning Revision Notes 9.2.2 Human activities which contribute to an increase in greenhouse gases in the atmosphere (AQA GCSE Chemistry 2, paper 2, Topic 9 "Chemistry of the atmosphere") Know that some human activities increase the amounts of greenhouse gases in the atmosphere. These include carbon dioxide from combustion of fossil fuels, deforestation, methane from animal farming (digestion, waste decomposition) and decomposition of rubbish in landfill sites. Appreciate that based on peer-reviewed evidence, many scientists believe that human activities will cause the temperature of the Earth’s atmosphere to increase at the surface and that this will result in global climate change. However, it is difficult to model such complex systems as global climate change. This leads to simplified models, speculation and opinions presented in the media that may be based on only parts of the evidence and which may be biased. You should be able to:
Greenhouse effect, global warming, climate change, carbon footprint from fossil fuel burning Revision Notes Recycling of gases - carbon cycle, global warming, oxygen balance and photosynthesis Revision Notes
Past ancient atmospheres, changes due to
man's activities Revision Notes 9.2.3 Global climate change (AQA GCSE Chemistry 2, paper 2, Topic 9 "Chemistry of the atmosphere") Know that an increase in average global temperature is a major cause of climate change. The potential effects of global climate change include eg sea level rise, which may cause flooding and increased coastal erosion, more frequent and severe storms, changes in the amount, timing and distribution of rainfall, temperature and water stress for humans and wildlife, changes in the food producing capacity of some regions and changes to the distribution of wildlife species. You should be able to:
Greenhouse effect, global warming, climate change, carbon footprint from fossil fuel burning Revision Notes 9.2.4 The carbon footprint and its reduction (AQA GCSE Chemistry 2, paper 2, Topic 9 "Chemistry of the atmosphere") Know that the carbon footprint is the total amount of carbon dioxide and other greenhouse gases emitted over the full life cycle of a product, service or event. The carbon footprint can be reduced by reducing emissions of carbon dioxide and methane. Possible actions to reduce the carbon footprint include eg increased use of alternative energy supplies, energy conservation, carbon capture and storage, carbon taxes and licences, carbon off-setting, including through tree planting, carbon neutrality – zero net release. Appreciate that problems of reducing the carbon footprint include eg scientific disagreement over causes and consequences of global climate change, lack of public information and education, lifestyle changes, economic considerations, incomplete international cooperation. You should be able to:
Greenhouse effect, global warming, climate change, carbon footprint from fossil fuel burning Word-fill quiz "Air pollution and the Earth's atmosphere" Word-fill quiz "Making sense of air pollution data" Index of topics for AQA GCSE Chemistry paper 1 and paper 2
9.3 Common atmospheric pollutants and their sources (AQA 9-1 GCSE Chemistry 2 paper 2) 9.3.1 Atmospheric pollutants from fuels (AQA GCSE Chemistry 2, paper 2, Topic 9 "Chemistry of the atmosphere") Know the combustion of fuels is a major source of atmospheric pollutants. Most fuels, including coal, contain carbon and/or hydrogen and may also contain some sulfur. The gases released into the atmosphere when a fuel is burned may include carbon dioxide, water vapour, carbon monoxide, sulfur dioxide and oxides of nitrogen. Solid particles and unburned hydrocarbons may also be released that form particulates in the atmosphere. Carbon monoxide and soot (carbon particles) are produced by incomplete combustion. Sulfur dioxide is produced by oxidation of sulfur in the fuel. Oxides of nitrogen are produced by the reaction of nitrogen and oxygen from the air at the high temperatures involved when fuels are burned. You should be able to:
Air pollution - sulfur oxides, nitrogen oxides, acid rain Revision Notes Air pollution - incomplete combustion, carbon monoxide & soot Revision Notes 9.3.2 Properties and effects of atmospheric pollutants (AQA GCSE Chemistry 2, paper 2, Topic 9 "Chemistry of the atmosphere") Know that carbon monoxide is a toxic gas. It is colourless and odourless and so is not easily detected. Carbon monoxide combines with haemoglobin in the blood, reducing its capacity to carry oxygen. Sulfur dioxide and oxides of nitrogen cause respiratory problems in humans and cause acid rain. Acid rain damages plants and buildings. Particulates cause:
You should be able to describe and explain the problems caused by increased amounts of pollutants in the air. Air pollution - sulfur oxides, nitrogen oxides, acid rain Revision Notes Air pollution - incomplete combustion, carbon monoxide & soot Revision Notes Index of topics for AQA GCSE Chemistry paper 1 and paper 2
Topic 10 Using Resources (AQA 9-1 GCSE Chemistry 2 paper 2) You should appreciate that industries use the Earth’s natural resources to manufacture useful products. In order to operate sustainably, chemists seek to minimise the use of limited resources, use of energy, waste and environmental impact in the manufacture of these products. Chemists also aim to develop ways of disposing of products at the end of their useful life in ways that ensure that materials and stored energy are utilised. Pollution, disposal of waste products and changing land use has a significant effect on the environment, and environmental chemists study how human activity has affected the Earth’s natural cycles, and how damaging effects can be minimised. Using the Earth's resources INDEX - metals, oil, water etc. Revision Notes HT = higher tier (harder - usually more theory & depth) and FT = foundation tier (easier) 10.1 Using the Earth's resources and obtaining potable water (AQA GCSE Chemistry 2, paper 2, Topic 10 "Using resources") 10.1.1 Using the Earth's resources and sustainable development Appreciate that we humans use the Earth’s resources to provide warmth, shelter, food and transport. Natural resources, supplemented by agriculture, provide food, timber, clothing and fuels. Finite resources from the Earth, oceans and atmosphere are processed to provide energy and materials. Chemistry plays an important role in improving agricultural and industrial processes to provide new products and in sustainable development, which is development that meets the needs of current generations without compromising the ability of future generations to meet their own needs. You should be able to:
An introduction to the Earth's resources & sustainability Revision Notes Products of the Chemical & Pharmaceutical Industries & Impact on Us Revision Notes Survey of the properties - related to uses, for a wide variety of materials Revision Notes 10.1.2 Potable water (AQA GCSE Chemistry 2, paper 2, Topic 10 "Using resources") Appreciate that water of appropriate quality is essential for life. For humans, drinking water should have sufficiently low levels of dissolved salts and microbes. Water that is safe to drink is called potable water. Potable water is not pure water in the chemical sense because it contains dissolved substances. The methods used to produce potable water depend on available supplies of water and local conditions. In the United Kingdom (UK), rain provides water with low levels of dissolved substances (fresh water) that collects in the ground and in lakes and rivers, and most potable water is produced by:
Sterilising agents used for potable water include chlorine, ozone or ultraviolet light. If supplies of fresh water are limited, desalination of salty water or sea water may be required. Desalination can be done by distillation or by processes that use membranes such as reverse osmosis. These processes require large amounts of energy. You should be able to:
In required practical 8 you should have experienced analysis and purification of water samples from different sources, including pH, dissolved solids and distillation. Water cycle, potable water, water treatment, pollution, tests for ions in water Revision Notes Summary of tests for ions including equations Revision Notes 10.1.3 Waste water treatment (AQA GCSE Chemistry 2, paper 2, Topic 10 "Using resources") Appreciate that urban lifestyles and industrial processes produce large amounts of waste water that require treatment before being released into the environment. Sewage and agricultural waste water require removal of organic matter and harmful microbes. Industrial waste water may require removal of organic matter and harmful chemicals. Sewage treatment includes:
You should be able to comment on the relative ease of obtaining potable water from waste, ground and salt water. Water cycle, potable water, water treatment, pollution, tests for ions in water Revision Notes 10.1.4 Alternative methods of extracting metals (HT only) (AQA GCSE Chemistry 2, paper 2, Topic 10 "Using resources") Appreciate that the Earth’s resources of metal ores are limited. Copper ores are becoming scarce and new ways of extracting copper from low-grade ores include phytomining, and bioleaching. These methods avoid traditional mining methods of digging, moving and disposing of large amounts of rock. Phytomining uses plants to absorb metal compounds. The plants are harvested and then burned to produce ash that contains the metal compounds. Bioleaching uses bacteria to produce leachate solutions that contain metal compounds. The metal compounds can be processed to obtain the metal. For example, copper can be obtained from solutions of copper compounds by displacement using scrap iron or by electrolysis. You should be able to evaluate alternative biological methods of metal extraction, given appropriate information. Copper extraction by phytomining or bioleaching Revision Notes Index of topics for AQA GCSE Chemistry paper 1 and paper 2
10.2 Life cycle assessment and recycling (AQA 9-1 GCSE Chemistry 2 paper 2) 10.2.1 Life cycle assessment (AQA GCSE Chemistry 2, paper 2, Topic 10 "Using resources") Know that life cycle assessments (LCAs) are carried out to assess the environmental impact of products in each of these stages:
Energy, water, resource consumption and production of some wastes can be fairly easily quantified. Allocating numerical values to pollutant effects is less straightforward and requires value judgements, so LCA is not a purely objective process. Selective or abbreviated LCAs can be devised to evaluate a product but these can be misused to reach pre-determined conclusions, eg in support of claims for advertising purposes. You should be able to carry out simple comparative LCAs for shopping bags made from plastic and paper. LCAs should be done as a comparison of the impact on the environment of the stages in the life of a product, and only quantified where data is readily available for energy, water, resources and wastes. Be able to interpret LCAs of materials or products given appropriate information. Be able to recognise and use expressions in decimal form. Be able to use ratios, fractions and percentages, make estimates of the results of simple calculations, use an appropriate number of significant figures and translate information between graphical and numeric form. Chemical & Pharmaceutical Industry Economics & Sustainability, Life Cycle Assessment, Recycling Notes 10.2.2 Ways of reducing the use of resources (AQA GCSE Chemistry 2, paper 2, Topic 10 "Using resources") Know that the reduction in use, reuse and recycling of materials by end users reduces the use of limited resources, use of energy sources, waste and environmental impacts. Metals, glass, building materials, clay ceramics and most plastics are produced from limited raw materials. Much of the energy for the processes comes from limited resources. Obtaining raw materials from the Earth by quarrying and mining causes environmental impacts. Some products, such as glass bottles, can be reused. Glass bottles can be crushed and melted to make different glass products. Other products cannot be reused and so are recycled for a different use. Metals can be recycled by melting and recasting or reforming into different products. The amount of separation required for recycling depends on the material and the properties required of the final product. For example, some scrap steel can be added to iron from a blast furnace to reduce the amount of iron that needs to be extracted from iron ore. You should be able to evaluate ways of reducing the use of limited resources, given appropriate information. Chemical & Pharmaceutical Industry Economics & Sustainability, Life Cycle Assessment, Recycling Notes Economic & environmental issues on mineral extraction & reasons for recycling and methods Revision Notes Index of topics for AQA GCSE Chemistry paper 1 and paper 2
10.3 Using materials (AQA GCSE Chemistry 2, paper 2, Topic 10 "Using resources") 10.3.1 Corrosion and its prevention Know that corrosion is the destruction of materials by chemical reactions with substances in the environment. Rusting is an example of corrosion. Both air and water are necessary for iron to rust. Corrosion can be prevented by applying a coating that acts as a barrier, such as greasing, painting or electroplating. Aluminium has an oxide coating that protects the metal from further corrosion. Some coatings are reactive and may contain corrosion inhibitors or a more reactive metal. Zinc is used to galvanise iron and when scratched provides sacrificial protection because zinc is more reactive than iron. Magnesium blocks can be attached to steel ships to provide sacrificial protection. You should be able to:
Introduction to oxidation and reduction theory and application to 'redox' reactions Revision Notes The corrosion of metals and the prevention of iron rusting Revision Notes 10.3.2 Alloys as useful materials (AQA GCSE Chemistry 2, paper 2, Topic 10 "Using resources") Know that most metals in everyday use are alloys. Pure copper, gold, iron and aluminium are too soft for many uses and so are mixed with other metals to make them harder for everyday use. Bronze is an alloy of copper and tin and is used to make statues and decorative objects. Brass is an alloy of copper and zinc used to make water taps and door fittings. Gold used as jewellery is usually an alloy with silver, copper and zinc. The proportion of gold in the alloy is measured in carats. 24 carat being 100% (pure gold), and 18 carat being 75% gold. Steels are alloys of iron that contain specific amounts of carbon and other metals. High carbon steel is strong but brittle. Low carbon steel is softer and more easily shaped. Steels containing chromium and nickel (stainless steels) are hard and resistant to corrosion. Aluminium alloys are low density and used in aerospace manufacturing. You should be able to
Metallic bonding, properties and uses of metals including alloys Revision Notes The Transition Metals eg iron, copper and gold - their uses (also mention of aluminium and other metals) Anodising and uses of aluminium Revision Notes 10.3.3 Ceramics, polymers and composites (AQA GCSE Chemistry 2, paper 2, Topic 10 "Using resources") Know that most of the glass we use is soda-lime glass, made by heating a mixture of sand, sodium carbonate and limestone. Borosilicate glass, made from sand and boron trioxide, melts at higher temperatures than soda-lime glass. Clay ceramics, including pottery and bricks, are made by shaping wet clay and then heating in a furnace. Limestone - section on glass, ceramics etc. Revision Notes The properties of polymers depend on what monomers they are made from and the conditions under which they are made. For example, low density (LD) and high density (HD) poly(ethene) are produced from ethene using different catalysts and reaction conditions. Thermosoftening polymers consist of individual, tangled polymer chains and melt when they are heated. Thermosetting polymers consist of polymer chains with cross-links between them and so they do not melt when they are heated. Students should be able to:
Addition polymer manufacture including LD and HD poly(ethene) Revision Notes Comparing addition polymers and condensation polymers, thermosets, fibres, thermosoftening polymers Most composites are made of two materials, a matrix or binder surrounding and binding together fibres or fragments of the other material, which is called the reinforcement. Examples of composites include wood, concrete and fibreglass. Some advanced composites are made using carbon fibres or carbon nanotubes instead of glass fibres. You should be able to recall some examples of composites. You should be able to, given appropriate information:
Glass, ceramics - properties and uses Revision Notes Addition polymers - plastics- properties and uses Revision Notes Comparing addition polymers & condensation polymers - thermosoftening and thermosetting polymers Notes Metallic bonding, properties and uses of metals Revision Notes Properties and uses of Transition Metals eg iron and copper (also mention of aluminium) Revision Notes 10.4 The Haber process and the use of NPK fertilisers (AQA 9-1 GCSE Chemistry 2 paper 2) 10.4.1 The Haber process (AQA GCSE Chemistry 2, paper 2, Topic 10 "Using resources") Know the Haber process is used to manufacture ammonia, which can be used to produce nitrogen based fertilisers. The raw materials for the Haber process are nitrogen and hydrogen. You should be able to recall a source of nitrogen and a source for hydrogen used in the Haber Process. Nitrogen is obtained from the air and hydrogen may be obtained from natural gas or other sources. The purified gases are passed over a catalyst of iron at a high temperature (about 450°C) and a high pressure (about 200 atmospheres). Some of the hydrogen and nitrogen reacts to form ammonia. The reaction is reversible so some of the ammonia produced breaks down into nitrogen and hydrogen: nitrogen + hydrogen
On cooling, the ammonia liquefies and is removed. The remaining hydrogen and nitrogen are recycled. (HT only) You should be able to:
Reversible Reactions - experiments described and explained Revision Notes Reversible reactions and chemical equilibrium Revision Notes The Haber Synthesis of ammonia - nitrogen fixation Revision Notes Multiple choice quiz on Reversible Reactions, Equilibrium, Ammonia Synthesis & Uses 10.4.2 Production and uses of NPK fertilisers (AQA GCSE Chemistry 2, paper 2, Topic 10 "Using resources") Know that compounds of nitrogen, phosphorus and potassium are used as fertilisers to improve agricultural productivity. NPK fertilisers contain compounds of all three elements. Industrial production of NPK fertilisers can be achieved using a variety of raw materials in several integrated processes. NPK fertilisers are formulations of various salts containing appropriate percentages of the elements. Ammonia can be used to manufacture ammonium salts and nitric acid. Potassium chloride, potassium sulfate and phosphate rock are obtained by mining, but phosphate rock cannot be used directly as a fertiliser. Phosphate rock is treated with nitric acid or sulfuric acid to produce soluble salts that can be used as fertilisers. You should be able to:
You should have done a practical to prepare an ammonium salt. The nitrogen cycle Revision Notes Multiple choice quiz on Reversible Reactions, Equilibrium, Ammonia Synthesis & Uses Index of topics for AQA GCSE Chemistry paper 1 and paper 2
ALL AQA GCSE (Grade 9-1) Level 1/Level 2 SCIENCES specifications and syllabus revision summary links AQA GCSE (Grade 9-1) BIOLOGY 8461 GCSE BIOLOGY 1st paper 1 (separate science Topics 1-4) AQA GCSE (Grade 9-1) BIOLOGY 8461 GCSE BIOLOGY 2nd paper 2 (separate science Topics 5-7) AQA GCSE (Grade 9-1) CHEMISTRY 8462 GCSE CHEMISTRY 1st Paper 1 (separate science Topics 1-5) AQA GCSE (Grade 9-1) CHEMISTRY 8462 GCSE CHEMISTRY 2nd Paper 2 (separate science Topics 6-10) AQA GCSE (Grade 9-1) PHYSICS 8463 GCSE PHYSICS 1st Paper 1 (separate science Topics 1-4) AQA GCSE (Grade 9-1) PHYSICS 8463 GCSE PHYSICS 2nd Paper 2 (separate science Topics 5-8) Watch out for HT Only sections AND make sure you know exactly which GCSE science course you are doing!
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INDEX
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Topic 6 The rate and extent of chemical change QUIZ (AQA
GCSE Chemistry)
