What are catalysts?
3 marks · EasyDescribe what happens to a catalyst at the end of a chemical reaction.
Explain why only a small amount of catalyst is needed to speed up a reaction.
Different reactions require different catalysts. Give one reason for this.
Work this out on paper, then compare with the answer and worked solution below. With a free account you can submit written answers for marking.
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(a) It is unchanged/chemically the same as before.
(b) Because the catalyst is not used up and can catalyse many reactions.
(c) Catalysts are specific: different reactions need different catalysts.
Show mark scheme and worked solution
Marking points
B1 (a) · 1 mark · Correct statement that the catalyst is unchanged/chemically unchanged at the end.
B1 (b) · 1 mark · Recognises that small amounts are needed as catalysts are not used up.
B1 (c) · 1 mark · States that different reactions require different catalysts because catalysts are specific.
Worked solution
a) The catalyst remains chemically unchanged at the end of the reaction.
b) Only a small amount is needed because the catalyst is not used up and one catalyst molecule can act on many reactant molecules.
c) Catalysts are specific; different reactions require different catalysts.