A solution changes colour during a reaction. A student measures how the colour fades as the reaction proceeds.
Which statement describes the rate of the reaction?
The time taken before the colour first starts to fade
The colour intensity recorded before the reactants are mixed
The time taken for each unit decrease in colour intensity
The decrease in colour intensity per unit time
122 exam-style questions on Edexcel GCSE Chemistry 8.1 Rates of reaction, covering 8.1.1 Measuring and interpreting rates of reaction, 8.1.2 Collision theory and the factors affecting rate, and 8.1.3 Catalysts and enzymes. Each one has a worked solution and a mark scheme showing where the marks go.