CAIE A Level Chemistry 9701 · Electrochemistry
The Roman numeral (IV) in the name lead(IV) oxide indicates the oxidation number of lead in . Lead(IV) oxide reacts with concentrated hydrochloric acid:
Explain, using oxidation numbers, why this reaction is a redox reaction, and identify the oxidising agent and the reducing agent.
4 marks, so the mark scheme is looking for about 4 separate creditworthy points. Making the same point twice in different words earns it once.
Explain means: Give the reasons or the mechanism: why or how something happens. Link each point to the next with because, so or which means. A list of facts with no links usually loses the reasoning marks.
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