Changing the temperature
3 marks · Easy| Temperature (°C) | % S at equilibrium | % T at equilibrium |
|---|---|---|
| 350 | 30 | 70 |
| 600 | 55 | 45 |
At which temperature is there more S at equilibrium?
Describe how increasing temperature affects the position of equilibrium in this reaction.
Suggest whether the forward reaction is likely to be exothermic or endothermic. Explain your answer.
Work this out on paper, then compare with the answer and worked solution below. With a free account you can submit written answers for marking.
Show answer
(a) At 600 °C · must show 600°C
(b) Increasing temperature increases the amount of S at equilibrium (position shifts towards S). · must show more S
(c) The forward reaction is likely exothermic because increasing temperature favours the reverse (S formation), so the forward is exothermic. · must show forward exothermic
Show mark scheme and worked solution
Marking points
B1 (a) · 1 mark · Correctly identifies 600°C as temperature with more S at equilibrium.
B1 (b) · 1 mark · States that increasing temperature shifts position towards S/more S is present.
M1 (c) · 1 mark · Correctly suggests forward reaction is exothermic (with explanation relating temperature and direction).
Worked solution
a) At 600°C, there is 55% S (more than at 350°C). b) Increasing the temperature increases amount of S, so equilibrium shifts towards S. c) The forward reaction must be exothermic because increasing temperature favours the endothermic direction (here, towards S, so reverse is endothermic, forward is exothermic).