A single use hand warmer contains iron powder and cannot be used again once the iron has been oxidised. Which statement is a disadvantage of this hand warmer compared with a reusable one?
The oxidation of the iron is exothermic and transfers energy to the surroundings
A new hand warmer has to be bought each time, so more waste is produced
The hand warmer becomes warm as soon as air is allowed to reach the iron
The temperature reached depends on the mass of iron powder in the packet
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.