A student investigates how the mass of magnesium affects the temperature rise when magnesium reacts with dilute hydrochloric acid. Which variable should be kept the same in every experiment?
The mass of magnesium that is added to the acid
The volume of hydrochloric acid that is used
The temperature rise that is measured each time
The time taken for the magnesium to disappear
39 exam-style questions on AQA GCSE Chemistry 5.1 Exothermic and endothermic reactions, covering 5.1.1 Energy transfer during exothermic and endothermic reactions, 5.1.2 Reaction profiles, and 5.1.3 The energy change of reactions. Each one has a worked solution and a mark scheme showing where the marks go.