#99
Energy changes
Paper 1 · Apply
Key steps (method)
- Decide if the process is exothermic or endothermic.
- For required practical / calorimetry: calculate energy using q = m c ΔT.
- Link energy profile diagrams to activation energy and overall energy change.
Common mistakes
- Using the wrong sign for ΔT or mixing endo/exo descriptions.
- Forgetting to convert units (e.g. mass in g vs kg) or using the wrong c.
- Confusing activation energy with energy released.
Exam-style questions (quick)
- Use q = m c ΔT to calculate energy change for a temperature rise.
- Sketch an energy profile for an exothermic reaction and label Ea.
- Explain how catalysts affect activation energy and rate.
Revision links
- FreeScienceLessons playlist: https://www.youtube.com/playlist?list=PL9IouNCPbCxX74bPfz0TGVVmyGYgMarWu
- PMT notes + questions: https://www.physicsandmathstutor.com/chemistry-revision/gcse-aqa/energy-changes/
- BBC Bitesize: https://www.bbc.co.uk/bitesize/topics/z34kgdm