Question 22M.2.sl.TZ2.3b(ii)
| Date | May 2022 | Marks available | [Maximum mark: 2] | Reference code | 22M.2.sl.TZ2.3b(ii) |
| Level | sl | Paper | 2 | Time zone | TZ2 |
| Command term | Explain | Question number | b(ii) | Adapted from | N/A |
Sulfur trioxide is produced from sulfur dioxide.
2SO2 (g) + O2 (g) 2SO3 (g) ΔH = −196 kJ mol−1
The reaction between sulfur dioxide and oxygen can be carried out at different temperatures.
Explain the effect of increasing temperature on the yield of SO3.
[2]
decrease AND equilibrium shifts left / favours reverse reaction ✔
«forward reaction is» exothermic / ΔH is negative ✔
Another question that showed a strong correlation with the candidates who did well overall. The average mark was 1 out of 2 marks. Many candidates explained the effect of an increase in temperature on the yield of SO3 correctly and thoroughly. One of the common mistakes was to miss the fact that it was an equilibrium and reason that yield would not change due to an increase in the rate of reaction. Unfortunately, a number of candidates also deduced that yield would increase due to the increase in rate. Other candidates recognized that it was an exothermic reaction but deduced the equilibrium would shift to the right giving a higher yield of SO3.
