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Edexcel A Level Chemistry

Topic 5
Formulae, Equations
& Amounts of Substance

Topic 5 builds the calculation and chemical language foundation for A Level Chemistry. It covers atoms, elements, ions, molecules, compounds, empirical formulae, molecular formulae, balanced equations, reacting masses, solution concentrations, gas volumes, titration calculations, percentage yield, atom economy, measurement uncertainty, errors, risks and hazards.

Exam Paper
Paper 1
9CH0/01
Specification Points
5.1 – 5.16
16 points covered
Sub-topics
7 lessons
Revision notes available
Exam Board
Edexcel
Pearson 9CH0

Revision Notes

7 revision notes, in the order the specification teaches them.

Single atoms beside a molecule of an element and a compound
1

Atoms, Elements and Molecules

Key definitions including atom, element, ion, molecule, compound, empirical formula and molecular formula.

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A level balance with the same atoms in each pan
2

Equations and Reaction Types

Balanced equations, ionic equations, state symbols, acid reactions and precipitation reactions.

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A heap of powder opening out into countless particles
3

Mole Calculations

The mole, Avogadro constant, molar mass, reacting masses, percentage yield and atom economy.

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A whole molecule beside its simplest repeating unit
4

Empirical and Molecular Formulae

Using experimental data, percentage composition and molar mass to calculate empirical and molecular formulae.

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Two beakers, one dilute and one concentrated
5

Calculations with Solutions and Gases

Concentrations, titration calculations, molar volume and reacting volumes of gases.

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A close view of a liquid level on a graduated scale
6

Measurement Uncertainty and Errors

Measurement errors, percentage uncertainty, sources of error and minimising uncertainty in practical work.

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Safety goggles beside a plain hazard diamond
7

Risks, Hazards and Practical Precautions

Understanding hazards, evaluating risks and suggesting appropriate precautions in practical procedures.

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Summary Map

Download, print and revise the key facts of this topic at a glance.

Summary map

Download, print and revise the key facts of this topic at a glance.

Illustration of a summary map: compounds joined by reaction arrows
Summary map · PDF

Atoms, Elements and Molecules Map

Edexcel A Level Chemistry · Topic 5 Formulae, Equations and Amounts of Substance · Atoms, Elements and Molecules

The whole section on one A4 page: atoms, elements, molecules, compounds and mixtures, ions, charges from the Periodic Table and formulae of ionic compounds.

Download the map6 key ideas + an ions table · A4 portrait · print ready
Illustration of a summary map: compounds joined by reaction arrows
Summary map · PDF

Uncertainty and Practical Safety Map

Edexcel A Level Chemistry · Topic 5 Formulae, Equations and Amounts of Substance · Uncertainty and Practical Safety

The whole section on one A4 page: uncertainty and percentage uncertainty, combining them, percentage error, minimising both, hazards, risks and precautions.

Download the map6 key ideas + a measurements table · A4 portrait · print ready

© 2026 Online Learning System. For personal study: printing is allowed; editing, copying and redistribution are not.

Virtual Lessons

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MCQ Bank

Multiple-choice papers on this topic, marked the moment you submit. MCQ (A) is free.

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Test yourself: 8 MCQ papers

Exam-style multiple-choice papers, marked the moment you submit with every answer explained. MCQ (A) is free.

8 exam-style multiple-choice papers, MCQ (A) to (H): 170 questions on Topic 5 Formulae, Equations and Amounts of Substance, written the way the exam asks them.

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SAQ Bank

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Revision Game

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Study Cards

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Specification

Every specification point in this topic, in the exam board's own words. Rate how confident you are with each one.

Official Pearson Edexcel documentsSpecification (opens the Pearson Edexcel website in a new tab)Data booklet (opens the Pearson Edexcel website in a new tab)

Self-assessment · 38 points

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5.1

  1. 5.1

    know that the mole (mol) is the unit for amount of a substance

    Revise

5.2

  1. 5.2

    be able to use the Avogadro constant, L, (6.02 × 1023 mol-1) in calculations

    Revise

5.3

  1. 5.3

    know that the molar mass of a substance is the mass per mole of the substance in g mol-1

    Revise

5.4

  1. a

    know what is meant by empirical formula

    Revise
  2. b

    know what is meant by molecular formula

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5.5

  1. a

    be able to use experimental data to calculate empirical formulae

    Revise
  2. b

    be able to use experimental data to calculate molecular formulae

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  3. c

    be able to use pV = nRT for gases and volatile liquids in empirical/molecular formula calculations

    Revise
  4. d

    know that empirical formula calculations may involve composition by mass data

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  5. e

    know that empirical formula calculations may involve percentage composition by mass data

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5.6

  1. a

    be able to write balanced full equations, including state symbols, for chemical reactions

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  2. b

    be able to write balanced ionic equations, including state symbols, for chemical reactions

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5.7

  1. a

    be able to calculate amounts of substance in reactions involving mass

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  2. b

    be able to calculate amounts of substance in reactions involving volume of gas

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  3. c

    be able to calculate amounts of substance in reactions involving volume of solution

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  4. d

    be able to calculate amounts of substance in reactions involving concentration

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  5. e

    know these calculations may involve reactants

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  6. f

    know these calculations may involve products

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5.8

  1. 5.8

    be able to calculate reacting masses from chemical equations, and vice versa, using the concepts of amount of substance and molar mass

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5.9

  1. 5.9

    be able to calculate reacting volumes of gases from chemical equations, and vice versa, using the concepts of amount of substance

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5.10

  1. 5.10

    be able to calculate reacting volumes of gases from chemical equations, and vice versa, using the concepts of molar volume of gases

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5.11

  1. a

    be able to calculate solution concentrations in mol dm-3

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  2. b

    be able to calculate solution concentrations in g dm-3

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  3. c

    be able to carry out simple acid-base titration calculations using a range of acids, alkalis and indicators

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  4. d

    know the use of phenolphthalein as an indicator

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  5. e

    know the use of methyl orange as an indicator

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5.12

  1. i

    be able to: calculate measurement uncertainties and measurement errors in experimental results

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  2. ii

    be able to: comment on sources of error in experimental procedures

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5.13

  1. 5.13

    understand how to minimise the percentage error and percentage uncertainty in experiments involving measurements

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5.14

  1. a

    be able to calculate percentage yields using chemical equations and experimental results

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  2. b

    be able to calculate percentage atom economies using chemical equations and experimental results

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  3. c

    know that atom economy = molar mass of desired product × 100% / sum of molar masses of all products

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5.15

  1. i

    be able to relate ionic and full equations, with state symbols, to observations from simple test tube reactions, to include: displacement reactions

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  2. ii

    be able to relate ionic and full equations, with state symbols, to observations from simple test tube reactions, to include: reactions of acids

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  3. iii

    be able to relate ionic and full equations, with state symbols, to observations from simple test tube reactions, to include: precipitation reactions

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5.16

  1. a

    understand risks in practical procedures

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  2. b

    understand hazards in practical procedures

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  3. c

    suggest appropriate precautions where necessary

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