#121
4.6.2.2 Energy changes and reversible reactions
Paper 2 · Higher combined
Spec reference: 4.6.2.2 (under 4.6.2).
What you need to know
- Required Practical 5: Measuring the Production of a Gas
- A reversible reaction is one in which the reactants form
- This method outlines one way to carry out an investigation to collect a gas from
- products. The products are then able to react together to
- a chemical reaction.
- reform the reactants.
- The practical involves changing the concentration of hydrochloric acid and
- measuring the volume of carbon dioxide gas produced when the acid reacts
KO match: Reversible Reactions
Support videos
- FreeScienceLessons (topic playlist): (use links below)
- PMT videos hub (Rate & extent): https://www.physicsandmathstutor.com/chemistry-revision/gcse-aqa/rate-and-extent-of-chemical-change/
Self-assessment (checklist)
- I can explain how the direction of reversible reactions
Key steps (method)
- Identify what the question is testing and use precise chemistry vocabulary.
- If it’s a calculation: write the equation/formula first, then substitute carefully.
Common mistakes
- Missing units/state symbols when asked.
- Giving a statement without linking cause → effect.
Exam-style questions (quick)
- Define the key term(s) for this point in the spec.
- Explain a typical property/result using particle/bonding ideas.
- Do a short calculation or interpretation step relevant to this point.
Practice questions
- PMT: Rate & extent (questions + notes): https://www.physicsandmathstutor.com/chemistry-revision/gcse-aqa/rate-and-extent-of-chemical-change/