A student investigates how the size of the pieces of a solid affects the rate at which it reacts with a solution. The gas produced is collected in a gas syringe, and its volume is recorded after 30 s.
Give two factors that should be controlled to make the comparison valid.
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.