What are catalysts?
2 marks · EasyA student uses 0.10 g of a catalyst in a reaction and finds that at the end of the reaction the mass of the catalyst is still 0.10 g. The student repeats the experiment with another sample of the same catalyst, starting with 0.12 g, and measures the mass again after the reaction. Explain, using a calculation, what mass of the catalyst the student should expect to find at the end of the second experiment.
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0.12 g (±0.01)
Also accept: 0.120 g
Common mistakes: Subtracting any mass; assuming catalyst is used up
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Marking points
M1 · 1 mark · Recognises that the mass of catalyst stays the same because catalysts are not used up in a reaction.
A1 · 1 mark · Correct final answer: 0.12 g.
Worked solution
Catalysts are not used up during a reaction, so the mass does not change.
Since the student started with 0.12 g, they should find 0.12 g at the end: