Question detail
In a reaction at equilibrium, how does an increase in pressure affect the rate of the forward and reverse reactions?
Try the question, check the answer, then read the explanation to understand the curriculum point.
At a glance
MCQ
Type
practice
Style
Topic
Chemical equilibria, Le Chatelier's principle and Kc
Question
- A. The forward reaction rate increases more than the reverse
- B. Both rates increase equally
- C. The reverse reaction rate increases more than the forward
- D. There is no effect on the reaction rates
Answer
The forward reaction rate increases more than the reverse
Explanation
The correct option is The forward reaction rate increases more than the reverse. The forward reaction rate increases more than the reverse is the best answer because it directly supports the AQA A-Level Chemistry objective to use Le Chatelier's principle to predict the effect of pressure changes. This reasoning is anchored to Equilibrium and Le Chatelier's principle in Chemical equilibria, Le Chatelier's principle and Kc, and it separates Le Chatelier from similar A-Level ideas rather than relying on a vague recall statement. Other options are weaker if they use the wrong evidence, calculation, mechanism, observation, unit, or conclusion for this subtopic.
Common mistake
Pressure Change Misunderstanding
Students often think that increasing pressure will always shift the equilibrium to the right, regardless of the reaction.
To fix this, remember that increasing pressure shifts the equilibrium towards the side with fewer moles of gas. Always analyze the balanced equation to determine the effect of pressure changes.
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