WJEC GCSE Science Double Award: Rate of chemical change (Unit 2, Chemistry 1) overview
An overview of the Rate of chemical change module in WJEC GCSE Science Double Award (Unit 2, Chemistry 1), mapping rates of reaction and collision theory, the factors affecting rate and catalysts, and measuring the rate of reaction.
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The Rate of chemical change module gathers the reaction-rate content of Chemistry 1 in WJEC GCSE Science Double Award. It explains how fast reactions go, why, and how we measure it. Collision theory ties the whole topic together. This page maps the module and links to a focused answer page for each part.
The topics in this module
- Rates of reaction and collision theory
- What the rate means, and collision theory with the activation energy. See Rates of reaction and collision theory.
- Factors affecting rate and catalysts
- Temperature, concentration, pressure, surface area and catalysts, each explained by collision theory. See Factors affecting rate and catalysts.
- Measuring the rate of reaction
- The methods, the required practical, and interpreting rate graphs. See Measuring the rate of reaction.
How this module fits the exam
These topics sit in Unit 2 (Chemistry 1), a written paper of 1 hour 15 minutes worth 15%. Questions mix recall (definitions, collision theory), the rate practical, calculation (average rate) and graph interpretation.
How to study this module
- Master collision theory. It explains every rate factor; learn the frequency and energy of collisions.
- Apply it to each factor. Temperature, concentration, pressure, surface area and catalysts.
- Understand catalysts. Not used up, lower the activation energy, and why they matter in industry.
- Know the methods. Gas syringe, balance, and the disappearing-cross practical, kept as a fair test.
- Read rate graphs. The steepest part is fastest; the flat part means the reaction has finished.
Then test yourself with the module quiz.