Sulfur dioxide reacts reversibly with chlorine to form sulfuryl chloride.
SO2(g)+Cl2(g)⇌SO2Cl2(g) \mathrm{SO_{2}(g) + Cl_{2}(g) \rightleftharpoons SO_{2}Cl_{2}(g)} SO2(g)+Cl2(g)⇌SO2Cl2(g)Chlorine is pale green. Sulfur dioxide and sulfuryl chloride are colourless. At the temperatures used, all three substances are gases.
Equal starting amounts of sulfur dioxide and chlorine are allowed to reach equilibrium at the same pressure. The table shows the percentage of sulfur dioxide converted into sulfuryl chloride.
| Temperature in °C | Sulfur dioxide converted in % |
|---|---|
| 120 | 51 |
| 160 | 29 |
Use the data to explain whether the forward reaction is exothermic or endothermic, and the colour change when an equilibrium mixture is cooled from 160 °C to 120 °C.
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.