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
Quantitative Chemistry
- 10 subtopics
- 30 things to know
- Paper 1
What Quantitative Chemistry covers
Quantitative Chemistry is examined in Chemistry Paper 1. It covers conservation of mass and balanced chemical equations, relative formula mass and concentration of solutions, mass changes when a gas is involved, and measurement uncertainty, moles, amounts of substances in equations, and balancing using moles, limiting reactants, percentage yield, atom economy, using concentrations of solutions in mol/dm and use of amount of substance in relation to volumes of gases.
Where it is assessed
Paper 1
Chemistry Paper 1: 1 hour 45 minutes, 100 marks, 50% of the GCSE.
Check the AQA specification ↗The 10 subtopics
Each one has its own page.
- Conservation of mass and balanced chemical equationsThe law of conservation of mass, calculating masses in sealed reactions, why reactions are shown by balanced equations, balancing the equations for hydrogen and methane burning, the difference between balancing numbers and subscripts, and counting atoms in formulae such as 3H₂SO₄ and 2Ca(OH)₂.Open →
- Relative formula mass and concentration of solutionsDefining and calculating relative formula mass, showing both sides of a balanced equation total the same, percentage by mass of an element, and concentration in g/dm³ from the mass of solute and the volume of solution.Open →
- Mass changes when a gas is involved, and measurement uncertaintyWhy a metal gains mass when heated in air and a carbonate loses mass when decomposed, apparent breaches of conservation of mass explained with particles, the effect of sealing the container, uncertainty from the range of repeats, accuracy, precision, repeatability and reproducibility, random and systematic errors, anomalous results, resolution and reading scales, and mean, median and mode.Open →
- MolesThe mole as the unit of chemical amount, why it is used, the mass of one mole from relative formula mass, the Avogadro constant, and converting between mass and moles.Open →
- Amounts of substances in equations, and balancing using molesThe steps of a reacting mass calculation, mole ratios from balancing numbers, worked masses for magnesium oxide, carbon dioxide and ammonia, deducing a balanced equation from reacting masses, and rearranging the moles formula.Open →
- Limiting reactantsWhat the limiting reactant is, why one reactant is used in excess and what happens to it, which reactant fixes the mass of product, and worked examples with magnesium, oxygen, acid and ammonia.Open →
- Percentage yieldWhy the theoretical mass of product is not always obtained, including reversible reactions, losses during separation and side reactions, yield and percentage yield, the percentage yield equation and why it cannot exceed 100%, worked percentage yield calculations, and calculating theoretical mass from a balanced equation.Open →
- Atom economyWhat atom economy measures and why a high value matters for sustainability and cost, the information and equation needed to calculate it, why a single-product reaction scores 100%, worked calculations for calcium oxide, iron and zinc oxide, and weighing atom economy against yield, rate, equilibrium and by-products when choosing a pathway.Open →
- Using concentrations of solutions in mol/dmConcentration in mol/dm³, calculating moles from concentration and volume, the mass of solute in a given volume, finding an unknown concentration from a titration, and what dilution does to concentration.Open →
- Use of amount of substance in relation to volumes of gasesWhy equal moles of any gas fill the same volume, the 24 dm³ molar volume at room temperature and pressure, converting between mass, moles and volume, and volumes of reacting gases from an equation.Open →
What you need to know
Answer each one before you reveal it.
Your recallNot started
Key term
Describe how a reacting mass calculation is carried out, why the equation must be balanced first, and apply it to 4.8 g of magnesium burning.
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24 g of magnesium reacts completely with oxygen to form 40 g of magnesium oxide. What mass of oxygen reacted?
Numbers
Calculate the percentage by mass of oxygen in CO₂, given relative atomic masses C = 12 and O = 16.
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In which unit are chemical amounts measured, and what is the symbol for that unit?
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Why is one of the two reactants often used in excess?
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No atoms are gained or lost in a reaction, so why is the calculated mass of product not always obtained?
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Explain why using reactions with a high atom economy matters for sustainable development.
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Apart from grams per cubic decimetre, in which unit can the concentration of a solution be measured?
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Which occupies the larger volume at the same temperature and pressure, 1 mol of hydrogen or 1 mol of carbon dioxide?
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Explain why the total mass inside a sealed container does not change when a reaction happens in it.
Numbers
Calculate the percentage by mass of nitrogen in NH₄NO₃, given relative atomic masses N = 14, H = 1 and O = 16.
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Explain why the mass of solid increases when a metal is heated in an open crucible in air.
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Which contains more molecules, one mole of oxygen or one mole of ammonia?
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What two pieces of information are needed to calculate the mass of a product from the mass of a reactant?
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What happens to the reactant that is present in excess?
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Give three reasons why the full theoretical mass of a product may not be obtained.
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Give an economic reason for choosing a reaction with a high atom economy.
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What does a concentration of 2 mol/dm³ tell you about a solution?
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Why must the temperature and pressure be stated whenever the volume of a gas is quoted?
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Give the balancing numbers needed for the equation H₂ + O₂ → H₂O.
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In which unit is the concentration of a solution given when it is measured as a mass in a given volume?
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Explain why the mass of solid falls when a metal carbonate is thermally decomposed in an open container.
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What name is given to the number of particles in one mole of a substance?
Process
Outline the steps used to calculate the mass of a product from a given mass of reactant.
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Which of two reactants decides the maximum amount of product that can form?
Process
Name a stage of a preparation at which product is commonly lost.
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What information is needed before the atom economy of a reaction can be calculated?
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How is the amount in moles of solute calculated from the concentration and the volume of a solution?
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State the temperature and pressure meant by room temperature and pressure.
Take Quantitative Chemistry further
The same content, four other ways.
Commonly confused
Pairs that lose marks when they are blurred together.
Percentage yield vs Atom economy
Percentage yield: product actually obtained as a share of the maximum theoretical amount. Atom economy: the share of reactant formula mass that ends up in the desired product.
Limiting reactant vs Excess reactant
Limiting reactant: the one completely used up, fixing how much product forms. Excess reactant: the one with some left over unreacted at the end.
Relative formula mass vs Mole
Relative formula mass: the sum of the atomic masses of every atom shown for a compound. Mole: the unit of chemical amount, containing the Avogadro constant of particles.
Questions from this topic
Each one with the model answer underneath.
- 1
State the law of conservation of mass.
Model answer
No atoms are lost or made during a chemical reaction, so the total mass of the products equals the total mass of the reactants.
- 2
In a reaction carried out in a sealed flask, 8 g of one reactant reacts completely with 12 g of another to give a single product. What mass of product forms?
Model answer
20 g, because the mass of the product must equal the total mass of the reactants.
- 3
24 g of magnesium reacts completely with oxygen to form 40 g of magnesium oxide. What mass of oxygen reacted?
Model answer
16 g, since the mass of the product equals the total mass of the reactants.
- 4
Explain why the total mass inside a sealed container does not change when a reaction happens in it.
Model answer
The atoms present are only rearranged into new substances, and none are lost or made, so the total mass stays the same.
- 5
Explain why chemical reactions can be represented by balanced symbol equations.
Model answer
Because no atoms are lost or made, the number of atoms of each element must be the same on both sides of the equation.
- 6
What does it mean to say that a symbol equation is balanced?
Model answer
There are the same numbers of atoms of each element on the left-hand side as on the right-hand side.
What is inside Levo
Six ways to work the same material.
Quantitative Chemistry revision questions
- What does Quantitative Chemistry cover in AQA GCSE Chemistry?
- 10 subtopics: conservation of mass and balanced chemical equations, relative formula mass and concentration of solutions, mass changes when a gas is involved, and measurement uncertainty, moles, amounts of substances in equations, and balancing using moles, limiting reactants, percentage yield, atom economy, using concentrations of solutions in mol/dm and use of amount of substance in relation to volumes of gases. Each one has its own page with questions and model answers.
- How is Quantitative Chemistry organised?
- By the AQA 8462 specification, subtopic by subtopic, so it matches the order you are taught it in.
Every question in Quantitative Chemistry, 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.
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