Some chemical reactions, such as the reaction between magnesium and hydrochloric acid, are exothermic.
Explain, in terms of bond breaking and bond forming, why a reaction is exothermic.
94 exam-style questions on Edexcel GCSE Chemistry 8.2 Heat energy changes in chemical reactions, covering 8.2.1 Exothermic and endothermic changes, 8.2.2 Bond breaking, bond making and overall energy change, 8.2.3 Calculating energy change from bond energies, and 8.2.4 Activation energy and reaction profiles. Each one has a worked solution and a mark scheme showing where the marks go.