Question detail
Which of the following best describes the effect of a catalyst on a reversible reaction?
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. It speeds up both directions equally
- B. It shifts the equilibrium toward the products
- C. It shifts the equilibrium toward the reactants
- D. It changes the equilibrium constant
Answer
It speeds up both directions equally
Explanation
The correct option is It speeds up both directions equally. It speeds up both directions equally is the best answer because it directly supports the AQA A-Level Chemistry objective to explain why catalysts do not change the position of equilibrium. This reasoning is anchored to Equilibrium and Le Chatelier's principle in Chemical equilibria, Le Chatelier's principle and Kc, and it separates change 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
Misunderstanding Catalyst Function
Students often think that catalysts change the position of equilibrium in a reaction.
Catalysts speed up the rate of reaching equilibrium but do not affect the equilibrium position itself. They provide an alternative pathway with a lower activation energy, allowing both forward and reverse reactions to occur more quickly without altering the concentrations of reactants and products at equilibrium.
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