IGCSE Chemistry: Chemical Reactions – Exam Tips & Revision Guide
This guide covers IGCSE Chemistry topic 7: chemical reactions. You will revise types of reaction (combination, decomposition, displacement, precipitation, neutralisation), rate of reaction (factors, collision theory), and reversible reactions (equilibrium).
Key concepts to revise
- Types – Combination (A + B → C); decomposition (C → A + B); displacement (A + BC → AC + B); precipitation (insoluble solid forms); neutralisation (acid + base → salt + water).
- Rate – Affected by concentration, temperature, surface area, catalyst; collision theory (more collisions, more frequent successful collisions).
- Reversible – Reaction can go both ways (e.g. N2 + 3H2 ⇌ 2NH3); equilibrium when forward and backward rates equal.
- Catalyst – Speeds up reaction; not used up; lowers activation energy.
Exam tips and command words
- State – The type of reaction from an equation (e.g. displacement, neutralisation).
- Describe – How to measure rate (e.g. loss of mass, volume of gas, time for cross to disappear).
- Explain – Why rate increases when concentration or temperature increases (more collisions; more successful collisions).
- Explain – What happens at equilibrium (forward and backward rates equal; concentrations constant).
Common mistakes
- Saying a catalyst “takes part in the reaction” (it is not used up; it is recovered).
- Confusing rate (speed of reaction) with yield (amount of product).
- Saying at equilibrium “reaction stops” (reaction continues both ways; rates are equal).
Revision checklist
- Identify the type of reaction from a given equation (combination, decomposition, displacement, neutralisation).
- Describe how to measure the rate of a reaction (one method).
- Explain the effect of concentration, temperature and catalyst on rate (collision theory).
- Describe reversible reactions and equilibrium (rates equal; concentrations constant).
Next steps
Book a free trial with an IGCSE Chemistry tutor to practise reaction types and rate questions, or explore Tutopiya’s learning portal for more revision resources.
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