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OCR A Level Chemistry A – Module 2 Foundations in Chemistry

Calculations with Solutions and Gases

Calculations with solutions and gases connect the mole concept to measurable laboratory quantities. These pages build from calculating gas volumes, through using concentration in mol dm−3, to interpreting very small concentrations expressed in parts per million.

These pages cover the mole, formulae and every calculation type; hydrated salts and measuring techniques follow with the supplementary set.

Exam Paper
Paper 1 & 2
H432/01 and H432/02
Specification Points
2.1.3(a) – 2.1.3(g)
4 points covered
Sub-topics
3 lessons
Revision notes available
Exam Board
OCR
H432 (2015 onwards)

Revision Notes

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

A gas syringe holding particles of gas
1

Molar Volume Calculations

Revise how the amount of gas in moles links to gas volume, including the use of molar gas volume in calculations.

Start revising
Two beakers, one dilute and one concentrated
2

Concentrations of Solutions

Practise using concentration, volume and amount of substance in mol dm−3 calculations.

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A burette dripping into a flask with a pink end point
3

Titration Calculations

Use concentration, volume and balanced equation ratios to calculate unknown concentrations from titration data.

Start revising

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

Solutions and Gases Map

OCR A Level Chemistry A · 2.1.3 Amount of substance · Solutions and gases

Solutions and gases on one A4 page: concentration, standard solutions, molar gas volume, pV = nRT and measuring mass, volumes and gas volumes.

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

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

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Revision Game

Match reagents to products, with your board's reagents and conditions.

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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 OCR documentsSpecification (opens the OCR website in a new tab)Data sheet (opens the OCR website in a new tab)

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2.1.3

  1. a (v)

    explanation and use of the term molar gas volume (gas volume per mole, units dm3 mol–1)

    Revise
  2. e (ii)

    calculations, using amount of substance in mol, involving gas volume

    Revise
  3. e (iii)

    calculations, using amount of substance in mol, involving solution volume and concentration

    Revise
  4. f

    the ideal gas equation: pV = nRT

    Revise
  5. g

    use of stoichiometric relationships in calculations

    Revise