Displacement reactions involving metal oxides
2 marks · EasyIn a reaction, magnesium metal is heated with iron(III) oxide. Explain, in terms of oxidation and reduction, what happens to the magnesium and to the iron.
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.
Show answer
Magnesium is oxidised because it gains oxygen. Iron(III) oxide is reduced because it loses oxygen. Magnesium acts as the reducing agent and iron(III) oxide as the oxidising agent.
Also accept: Magnesium loses electrons (is oxidised), iron(III) oxide gains electrons (is reduced).
Common mistakes: Stating the wrong element is oxidised or reduced; Confusing oxygen gain and loss
Show mark scheme and worked solution
Marking points
M1 · 1 mark · Identifies that magnesium is oxidised (gains oxygen), iron is reduced (loses oxygen).
A1 · 1 mark · Correct reasoning: magnesium is the reducing agent, iron(III) oxide is the oxidising agent / correct use of both terms.
Worked solution
When magnesium reacts with iron(III) oxide: - Magnesium is oxidised (gains oxygen and forms magnesium oxide). - Iron(III) oxide is reduced (loses oxygen and forms iron). Magnesium acts as the reducing agent; iron(III) oxide is the oxidising agent.