Question detail
What is the primary reason that adding a catalyst to a reversible reaction does not alter the equilibrium composition?
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 provides a lower-energy pathway for both directions of the reaction
- B. It consumes some reactants, reducing their concentration
- C. It increases the temperature of the system
- D. It changes the stoichiometry of the balanced equation
Answer
It provides a lower-energy pathway for both directions of the reaction
Explanation
The correct option is It provides a lower-energy pathway for both directions of the reaction. It provides a lower-energy pathway for both directions of the reaction 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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