Oxidation and reduction
3 marks · NormalExplain why magnesium acts as a reducing agent when it is heated with zinc oxide, in terms of oxygen transfer.
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Also accept: magnesium takes oxygen from zinc oxide; magnesium causes zinc oxide to lose oxygen
Common mistakes: explanations in terms of electrons only
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Marking points
M1 · 1 mark · States that a reducing agent removes oxygen from another substance.
M2 · 1 mark · Explains that magnesium causes zinc oxide to lose oxygen.
A1 · 1 mark · Links the idea to magnesium's role in the reaction (magnesium gains oxygen; zinc oxide loses oxygen).
Worked solution
A reducing agent is a substance that removes oxygen from another substance.
When magnesium is heated with zinc oxide, magnesium removes oxygen from zinc oxide.
This means magnesium is the reducing agent because it causes zinc oxide to lose oxygen, and itself gains oxygen in the process.