The chemicals in a match head do not burn until the match is struck against the side of the box.
Why does striking the match make it start to burn?
The friction makes the reaction change from endothermic to exothermic.
The friction supplies all the energy that is given out when the match burns.
The friction lowers the energy of the products so the reaction can happen.
The friction supplies the energy needed to start the reaction.
51 exam-style questions on OCR GCSE Chemistry 3.2 Energetics, covering 3.2.1 Exothermic and endothermic reactions and reaction profiles and 3.2.2 Calculating energy change from bond energies. Each one has a worked solution and a mark scheme showing where the marks go.