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Use of amount of substance in relation to volumes of gases (chemistry only) (HT only)
This chemistry-only higher-tier topic connects moles, gas volume, relative formula mass, balanced equations and unit conversion at room temperature and pressure.
11
Objectives
10
Flashcards
10
Questions
90 min
Study time
AqaGcseChemistryQuantitative chemistry
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Syllabus checklist
What you need to know
11 objective pages available
Gas volumes and amount of substance11 objectives
- (chemistry only) (HT only) State that equal amounts in moles of gases occupy the same volume under the same temperature and pressure conditions.
- (chemistry only) (HT only) State that one mole of any gas at room temperature and pressure occupies 24 dm3.
- (chemistry only) (HT only) Calculate the volume of a gas at room temperature and pressure from its amount in moles.
- (chemistry only) (HT only) Calculate the volume of a gas at room temperature and pressure from its mass and relative formula mass.
- (chemistry only) (HT only) Calculate amount in moles from gas volume at room temperature and pressure.
- (chemistry only) (HT only) Calculate volumes of gaseous reactants and products from a balanced equation.
- (chemistry only) (HT only) Calculate gas volumes from a given volume of a gaseous reactant or product.
- (chemistry only) (HT only) Change the subject of equations used for gas-volume calculations. (MS 3b)
- (chemistry only) (HT only) Substitute numerical values into equations using appropriate units. (MS 3c)
- (chemistry only) (HT only) Use ratios, fractions and percentages in gas-volume calculations. (MS 1c)
- (chemistry only) (HT only) Convert between cm3 and dm3 where needed in gas-volume calculations.
Key terms
molegas volumeroom temperature and pressure (RTP)24 dm3Gas volume at RTPRelative formula mass (Mr)Gas volumeMole
Exam tips
- Understand Gas Volume Relationships: Remember that equal moles of gases occupy the same volume at the same temperature and pressure. Use this to simplify calculations.
- Remember the Gas Volume: Calculate carefully by always recall that one mole of any gas occupies 24 dm3 at room temperature and pressure when answering gas volume questions. Link your answer to Gas volumes and amount of substance in Use of amount of substance in relation to volumes of gases (chemistry only) (HT only), and show formula, substitution, calculation, final answer, and unit where relevant.
Common mistakes
- Confusing Moles with Volume: Remember that equal amounts in moles of gases occupy the same volume only under the same temperature and pressure conditions. Always check these conditions when making calculations. Keep the correction anchored to Gas volumes and amount of substance; check formula, substitution, calculation, final answer, and unit where relevant.
- Misunderstanding Gas Volume: Remember that at room temperature and pressure, one mole of any gas occupies 24 dm3, not 22.4 dm3. Use this value in calculations involving gas volumes.
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