DP Chemistry (first assessment 2025)
Question 22M.2.SL.TZ2.b(ii)
| Date | May 2022 | Marks available | [Maximum mark: 2] | Reference code | 22M.2.SL.TZ2.b(ii) |
| Level | SL | Paper | 2 | Time zone | TZ2 |
| Command term | Explain | Question number | b(ii) | Adapted from | N/A |
b(ii).
[Maximum mark: 2]
22M.2.SL.TZ2.b(ii)
Explain the effect of increasing temperature on the yield of SO3.
[2]
Markscheme
decrease AND equilibrium shifts left / favours reverse reaction ✔
«forward reaction is» exothermic / ΔH is negative ✔
Examiners report
Many candidates got one mark at least, sometimes failing to state the effect on the production of SO3 though they knew this quite obviously. This failure to read the question properly also resulted in an incorrect prediction based exclusively on kinetics instead of using the information provided to guide their answers.
Syllabus sections
Reactivity 2. How much, how fast and how far? » Reactivity 2.3—How far? The extent of chemical change » Reactivity 2.3.4—Le Châtelier’s principle enables the prediction of the qualitative effects of changes in concentration, temperature and pressure to a system at equilibrium. Apply Le Ch.telier’s principle to predict and explain responses to changes of systems at equilibrium.
Reactivity 2. How much, how fast and how far? » Reactivity 2.1—How much? The amount of chemical change » Reactivity 2.1.4—The percentage yield is calculated from the ratio of experimental yield to theoretical yield. Solve problems involving reacting quantities, limiting and excess reactants, theoretical, experimental and percentage yields.