Key term
AQA GCSE Combined Science Chemistry 8464
Atomic Structure and the Periodic Table
Topic overviewAtoms, elements and compoundsWord equations, symbols and balanced equationsMixturesFrom the plum pudding model to the nuclear modelBohr, Chadwick and the modern model of the atomRelative electrical charges of subatomic particlesSize and mass of atomsRelative atomic mass and electronic structureThe periodic tableDevelopment of the periodic tableMetals and non-metalsGroup 0Group 1Group 7
Bonding, Structure, and the Properties of Matter
Topic overviewChemical bonds, including metallic bondingIonic bondingIonic compoundsCovalent bonding and how it is representedThe three states of matter and changes of statePredicting state, state symbols, and the limits of the particle modelProperties of ionic compoundsProperties of small moleculesPolymers and giant covalent structuresProperties of metals and alloys, and why metals conductDiamond and graphiteGraphene and fullerenes
Chemical Analysis
Chemical Changes
Topic overviewThe reactivity seriesMetal oxides, extraction, and redox in terms of electronsAcids reacting with metals, neutralisation and saltsSoluble saltsThe pH scale and neutralisationThe process of electrolysis, and molten ionic compoundsUsing electrolysis to extract metalsElectrolysis of aqueous solutions
Chemistry of the Atmosphere
Topic overviewThe Earth's early atmosphereHow oxygen increased and carbon dioxide decreasedThe gases in today's atmosphere, and which are greenhouse gasesHuman activities which contribute to an increase in greenhouse gases in the atmosphereGlobal climate change and carbon footprintsAtmospheric pollutants from fuels, and their effects
Energy Changes
Organic Chemistry
Quantitative Chemistry
The Rate and Extent of Chemical Change
The Rate and Extent of Chemical Change
- 6 subtopics
- 18 things to know
- Chemistry Paper 2
What The Rate and Extent of Chemical Change covers
The Rate and Extent of Chemical Change is examined in Chemistry Paper 2. It covers measuring the mean rate of a reaction, rate from graphs and drawing tangents, factors which affect the rates of chemical reactions, collision theory and activation energy, catalysts and reversible reactions and dynamic equilibrium.
Where it is assessed
Chemistry Paper 2
Combined Science: Trilogy, Chemistry Paper 2: 1 hour 15 minutes, 70 marks, 16.7% of the qualification.
Check the AQA specification ↗The 6 subtopics
Each one has its own page.
- Measuring the mean rate of a reactionFollowing the quantity of reactant used or product formed over time, using a balance for a gas-producing reaction, the mean rate equations, worked calculations, and the units g/s and cm³/s.Open →
- Rate from graphs, and the gradient of a tangentMean rate calculations, the shape of a volume against time graph and what a horizontal section means, drawing a tangent to find the rate at one moment, comparing rates by steepness and why a curve is steepest at the start, plotting graphs with a line of best fit, y = mx + c, gradients and intercepts of straight lines, and direct proportionality.Open →
- Factors which affect the rates of chemical reactionsThe five factors that affect rate, the effects of concentration, temperature, surface area, gas pressure and catalysts, investigating concentration by gas volume and by the disappearing cross, why rate is proportional to one over the time taken, identifying variables, and writing a hypothesis.Open →
- Collision theory and activation energyThe two conditions for colliding particles to react and activation energy, what collision theory explains, why higher concentration, gas pressure, surface area and temperature make collisions more frequent or more energetic, surface area to volume ratio, predicting rate changes when conditions are altered, and the symbols for proportionality, much less than, much greater than and approximately.Open →
- CatalystsWhat a catalyst is and why little is needed, why different reactions need different catalysts, enzymes as biological catalysts, how a catalyst provides a pathway with lower activation energy without changing the amount of product or the energy change, its effect on a reaction profile, identifying one, and industrial uses.Open →
- Reversible reactions and dynamic equilibriumReversible reactions and the ⇌ symbol, forward and reverse reactions and changing direction by altering conditions, heating and rehydrating copper sulfate, equal energy transferred in each direction, the closed system needed for equilibrium, and equilibrium as forward and reverse reactions continuing at the same rate.Open →
What you need to know
Answer each one before you reveal it.
Your recallNot started
Key term
Name the independent variable, the dependent variable and two control variables in an investigation of how concentration affects rate.
Key term
Name the two kinds of measurement that can be followed over time to find the rate of a chemical reaction.
Process
State what a horizontal section on a graph of quantity of product against time tells you about the reaction.
Key term
State the two conditions that must be met when reacting particles meet if a reaction is to happen.
Key term
Define a catalyst.
Key term
Describe the symbol written between the reactants and the products of a reversible reaction.
Key term
Explain why a single measurement of the mass of product made is not enough to give the rate of a reaction.
Numbers
A reaction produces 30 cm³ of gas in the first 50 s. Calculate the mean rate over that period.
Key term
Explain why not every collision between reacting particles produces a reaction.
Key term
Explain why only a small amount of a catalyst is needed even for a reaction that is run many times.
Key term
In the reversible reaction A + B ⇌ C + D, name the substances that are the products of the reverse reaction.
Key term
Describe how a balance can be used to follow the rate of a reaction that gives off a gas.
Process
Explain why a graph of product formed against time is steepest at the very beginning of a reaction.
Key term
Name the five factors that affect the rate of a chemical reaction.
Key term
Explain, using collision theory, why increasing the pressure of reacting gases increases the rate of reaction.
Key term
Describe how the reaction profile of a catalysed reaction differs from that of the same reaction without a catalyst.
Key term
State what has to be altered to change the direction in which a reversible reaction goes.
Take The Rate and Extent of Chemical Change further
The same content, four other ways.
Commonly confused
Pairs that lose marks when they are blurred together.
Reversible reaction vs Equilibrium
Reversible reaction: one whose products can react together to re-form the reactants. Equilibrium: the state where the forward and reverse reactions run at the same rate.
Activation energy vs Rate of reaction
Activation energy: the minimum energy that particles must have to react when they collide. Rate of reaction: how quickly reactant is used up or product is formed.
Concentration vs Pressure
Concentration: how many reacting particles are in a given volume of solution. Pressure: how closely packed the particles of reacting gases are.
Questions from this topic
Each one with the model answer underneath.
- 1
Name the two kinds of measurement that can be followed over time to find the rate of a chemical reaction.
Model answer
The quantity of a reactant used up, or the quantity of a product formed.
- 2
Explain why a single measurement of the mass of product made is not enough to give the rate of a reaction.
Model answer
Rate compares how much is made or used with how long it took, so the time taken must be measured as well.
- 3
Describe how a balance can be used to follow the rate of a reaction that gives off a gas.
Model answer
The reaction vessel is stood on a balance and the mass is recorded at regular times; the mass falls as the gas escapes.
- 4
State the equation for the mean rate of a reaction written in terms of the reactant.
Model answer
Mean rate of reaction = quantity of reactant used ÷ time taken.
- 5
A reaction uses up 2.4 g of magnesium in 60 s. Calculate the mean rate of reaction.
Model answer
2.4 g ÷ 60 s = 0.04 g/s.
- 6
A reaction uses 6.0 g of a reactant at a mean rate of 0.25 g/s. Calculate the time taken.
Model answer
6.0 g ÷ 0.25 g/s = 24 s.
What is inside Levo
Six ways to work the same material.
The Rate and Extent of Chemical Change revision questions
- What does The Rate and Extent of Chemical Change cover in AQA GCSE Combined Science Chemistry?
- 6 subtopics: measuring the mean rate of a reaction, rate from graphs, and the gradient of a tangent, factors which affect the rates of chemical reactions, collision theory and activation energy, catalysts and reversible reactions and dynamic equilibrium. Each one has its own page with questions and model answers.
- How is The Rate and Extent of Chemical Change organised?
- By the AQA 8464 specification, subtopic by subtopic, so it matches the order you are taught it in.
Every question in The Rate and Extent of Chemical Change, on a schedule.
Attempt a question from memory, write the correct version, then attempt it again. Levo records the jump between your first attempt and your last, and brings each question back on the day you are due to forget it.
Or £46 a year, about £3.83 a month. Cancel anytime.