Changing the temperature
2 marks · HardA reversible reaction is at equilibrium. The forward reaction is exothermic. Explain what happens to the position of equilibrium if the temperature is increased.
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The position of equilibrium shifts towards the reverse (endothermic) reaction when temperature is increased.
Also accept: Equilibrium shifts to favour the endothermic (reverse) direction.; The yield of products from the exothermic reaction decreases.
Common mistakes: Stating that the equilibrium does not change.; Saying the forward (exothermic) reaction is favoured when temperature rises.
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Marking points
M1 · 1 mark · Identifies that the position of equilibrium shifts (moves) when temperature is increased.
A1 · 1 mark · Explains it shifts to favour the endothermic (reverse) reaction.
Worked solution
When temperature is increased, the system seeks to absorb the extra heat.
For a reaction where the forward direction is exothermic, increasing temperature favours the endothermic (reverse) reaction.
Therefore, the position of equilibrium shifts in the reverse direction.