Carbon monoxide and chlorine react reversibly in a closed reactor to form carbonyl chloride.
CO(g)+Cl2(g)⇌COCl2(g) \mathrm{CO(g) + Cl_{2}(g) \rightleftharpoons COCl_{2}(g)} CO(g)+Cl2(g)⇌COCl2(g)A chemist carries out three experiments using the same starting amounts of gases. Only the temperature and the use of a catalyst are changed.
| Temperature in °C | Catalyst used | Equilibrium yield of carbonyl chloride in % | Time taken to reach equilibrium in minutes |
|---|---|---|---|
| 250 | No | 88 | 60 |
| 350 | No | 67 | 18 |
| 250 | Yes | 88 | 14 |
Evaluate whether the chemist should increase the temperature to 350 °C or add the catalyst at 250 °C to obtain a high yield of carbonyl chloride in a short time. Explain what the results show about the energy transfer in the forward reaction.
124 exam-style questions on OCR GCSE Chemistry 5.3 Equilibria, covering 5.3.1 Reversible reactions and dynamic equilibrium and 5.3.2 Changing the position of equilibrium. Each one has a worked solution and a mark scheme showing where the marks go.