Oxidation and reduction
4 marks · NormalPotassium chlorate(V) reacts on heating with manganese(IV) oxide catalyst:
Identify which substance is reduced and which is oxidised in this reaction.
Name the oxidising agent in this reaction. Explain your answer.
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(a) Potassium chlorate(V) is reduced; potassium chloride is formed by reduction. Oxygen is oxidised (as O2 is evolved from KClO3). · must show KClO3 is reduced, O2/Oxygen is formed (by oxidation)
(b) Potassium chlorate(V) is the oxidising agent because it gives oxygen to other substances. · must show KClO3 is oxidising agent, justification: gives oxygen
Common mistakes: reversal of concepts
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Marking points
B1 (a) · 1 mark · Identifies potassium chlorate(V) is reduced.
B2 (a) · 1 mark · Identifies oxygen as the product that is oxidised (released from KClO3).
B3 (b) · 1 mark · Names potassium chlorate(V) as the oxidising agent.
B4 (b) · 1 mark · Explains this is because it gives oxygen to other substances.
Worked solution
a:
Potassium chlorate(V) is reduced as it loses oxygen.
Oxygen is formed (oxidised state, as O2 is released).
b:
Potassium chlorate(V) is the oxidising agent because it gives oxygen to other substances.