A manufacturer is selecting a reaction for a self-warming transport sleeve. For each trial, a sealed pouch containing the reacting chemicals is placed in the same volume of water using the same apparatus.
The temperature of the water is recorded immediately before the reaction starts and at its highest value.
| Reaction | Starting temperature (∘C^\circ\mathrm{C}∘C) | Highest temperature (∘C^\circ\mathrm{C}∘C) |
|---|---|---|
| P | 18.0 | 27.0 |
| Q | 21.5 | 27.5 |
| R | 19.0 | 29.5 |
| S | 22.0 | 30.0 |
Which reaction transfers the least energy to the surroundings?
Reaction P
Reaction S
Reaction R
Reaction Q
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.