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
Measuring the mean rate of a reaction
- 3 things to know
- Chemistry Paper 2
Overview
Following 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.
What you need to know
Answer each one before you reveal it.
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Key term
Explain why a single measurement of the mass of product made is not enough to give the rate of a reaction.
Key term
Describe how a balance can be used to follow the rate of a reaction that gives off a gas.
Questions from this subtopic
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.
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