Iron powder reacts with oxygen in a disposable hand warmer. The reaction transfers energy to the surroundings.
Its reaction profile starts at the energy of the reactants, rises to a peak and then falls to the lower energy of the products.
Why does the reaction profile rise to a peak?
Colliding reactant particles need a minimum energy for the reaction to happen.
The reactants release energy to the surroundings as their energy rises to the peak.
The peak is the energy level of the products while they are being formed.
The peak represents the overall energy transferred from the reaction to the surroundings.
106 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.