Key term
AQA GCSE Chemistry 8462
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 7Transition metals, and how they differ from Group 1
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 fullerenesSizes of particles and their propertiesUses of nanoparticles
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 neutralisationTitrationsStrong and weak acidsThe process of electrolysis, and molten ionic compoundsUsing electrolysis to extract metalsElectrolysis of aqueous solutionsRepresentation of reactions at electrodes as half equations
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
Topic overviewCrude oil, hydrocarbons and alkanesFractional distillation and petrochemicalsProperties of hydrocarbonsCracking, and testing alkenes with bromine waterWhy cracking is useful, and equations for itStructure and formulae of alkenesReactions of alkenesAlcoholsCarboxylic acidsAddition polymerisationCondensation polymerisationAmino acids, DNA and naturally occurring polymers
Quantitative Chemistry
Topic overviewConservation of mass and balanced chemical equationsRelative formula mass and concentration of solutionsMass changes when a gas is involved, and measurement uncertaintyMolesAmounts of substances in equations, and balancing using molesLimiting reactantsPercentage yieldAtom economyUsing concentrations of solutions in mol/dmUse of amount of substance in relation to volumes of gases
The Rate and Extent of Chemical Change
Topic overviewMeasuring the mean rate of a reactionRate from graphs, and the gradient of a tangentFactors which affect the rates of chemical reactionsCollision theory and activation energyCatalystsReversible reactions and dynamic equilibriumThe effect of changing conditions on equilibriumThe effect of changing concentrationThe effect of temperature changes on equilibriumThe effect of pressure changes on equilibrium
Using Resources
Topic overviewUsing the Earth's resources and sustainable developmentProducing potable water in the UKDesalination, and analysing water samplesWaste water treatmentAlternative methods of extracting metalsLife cycle assessmentWays of reducing the use of resourcesCorrosion and its preventionAlloys as useful materialsGlass, clay ceramics and polymersComposites, and comparing materialsThe Haber processProduction and uses of NPK fertilisers
The Rate and Extent of Chemical Change
Rate from graphs, and the gradient of a tangent
- 3 things to know
- Paper 2
Overview
Rate in mol/s, the shape of a volume against time graph and what a horizontal section means, drawing a tangent to find the rate at one moment and calculating its gradient, why a curve is steepest at the start and flattens, plotting graphs with a line of best fit, y = mx + c, gradients and intercepts, and direct proportionality.
What you need to know
Answer each one before you reveal it.
Your recallNot started
Numbers
A reaction uses 0.05 mol of a reactant in 25 s. Calculate the mean rate of reaction in mol/s.
Key term
Explain why the rate of the same reaction can be quoted in g/s, in cm³/s or in mol/s.
Questions from this subtopic
Each one with the model answer underneath.
- 1
Give the unit of rate of reaction used when the quantity of reactant is measured in moles.
Model answer
Moles per second, mol/s.
- 2
A reaction uses 0.05 mol of a reactant in 25 s. Calculate the mean rate of reaction in mol/s.
Model answer
0.05 mol ÷ 25 s = 0.002 mol/s.
- 3
Explain why the rate of the same reaction can be quoted in g/s, in cm³/s or in mol/s.
Model answer
Rate is any measure of quantity changed divided by time, and mass, gas volume and amount in moles are all ways of stating that quantity.
- 4
Describe the shape of a graph of volume of gas produced against time for a reaction that slows down and then stops.
Model answer
It is steepest at the start, then curves and becomes less steep, and finally flattens into a horizontal line.
- 5
A reaction produces 30 cm³ of gas in the first 50 s. Calculate the mean rate over that period.
Model answer
30 cm³ ÷ 50 s = 0.6 cm³/s.
- 6
State what a horizontal section on a graph of quantity of product against time tells you about the reaction.
Model answer
The reaction has finished, so no more product is forming and the rate is zero.
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