What are catalysts?
2 marks · NormalState what a catalyst is and explain why the same catalyst can be used again in another reaction of the same type.
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Also accept: A catalyst speeds up a reaction and is chemically unchanged at the end.; It can be used again because it is not used up in the reaction.
Common mistakes: Saying catalysts increase yield; Saying catalysts are consumed
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Marking points
B1 · 1 mark · States that a catalyst speeds up a reaction but is not used up (chemically unchanged at the end).
B2 · 1 mark · Explains that the catalyst can be reused in another reaction because it is unchanged.
Worked solution
A catalyst is a substance that speeds up a chemical reaction but is not used up in the reaction; it is chemically unchanged at the end. Because it remains unchanged, the same catalyst can be used again in another reaction of the same type.