What are catalysts?
3 marks · EasyWrite the word equation for the decomposition of hydrogen peroxide.
Write the balanced symbol equation for this reaction.
Explain why the catalyst is not shown among the reactants or products in these equations.
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) hydrogen peroxide → water + oxygen
(b) 2H2O2(aq) → 2H2O(l) + O2(g)
(c) Because the catalyst is not used up or changed by the reaction.
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Marking points
B1 (a) · 1 mark · Correct word equation given.
B1 (b) · 1 mark · Correct balanced symbol equation given.
B1 (c) · 1 mark · Reason for not showing catalyst: it is not used up / not chemically changed.
Worked solution
a) hydrogen peroxide → water + oxygen
c) The catalyst is not changed or used up during the reaction, so it does not appear among reactants or products.