Adding a catalyst
2 marks · EasyA student claims that adding a catalyst to a reversible reaction will result in more products being formed at equilibrium. Explain, with reasons, whether the student is correct.
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The student is incorrect. Adding a catalyst does not change the amount of products at equilibrium because it increases the rate of both the forward and reverse reactions equally. It only speeds up how quickly equilibrium is reached.
Also accept: The amount of products does not change because the position of equilibrium stays the same.
Common mistakes: Saying more products are formed at equilibrium
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Marking points
M1 · 1 mark · States that the catalyst does not change the position of equilibrium or amount of products at equilibrium.
M2 · 1 mark · Explains the reason: the catalyst speeds up both the forward and reverse reactions equally, only changing the rate at which equilibrium is reached.
Worked solution
The student is not correct. Adding a catalyst does not affect the position of equilibrium, so it does not change the amount of products present at equilibrium. The catalyst speeds up the forward and backward reactions by the same amount, simply making equilibrium happen faster.