A thermal energy store uses a reaction that can go in both directions. Substance X changes into substance Y, and Y can change back into X.
The table gives energy levels from the reaction profile.
| Position in the reaction profile | Energy (kJ/mol) |
|---|---|
| X | 210 |
| Peak | 285 |
| Y | 150 |
Calculate the activation energy for the reaction from X to Y and for the reaction from Y to X.
During charging, energy is taken in and stored in the chemicals. Explain which substance, X or Y, is made during charging.
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.