Displacement reactions involving metal oxides
5 marks · HardA student heats powdered samples of four different metals (A, B, C, D) separately with iron(III) oxide. The results are shown:
| Metal | Observation with iron(III) oxide |
|---|---|
| A | A bright reaction. Grey metal formed. |
| B | No visible change. |
| C | Slow reaction with faint glow. Grey metal appeared. |
| D | No reaction even after strong heating. |
Arrange the four metals (A, B, C, D) in order of their reactivity, from most reactive to least reactive, based on the observations above.
Suggest what happens chemically when metal A reacts with iron(III) oxide. State which metal is reduced and which is oxidised.
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
(a) A > C > B ≈ D (A is most reactive, C next, B and D least/equal reactivity).
(b) Metal A displaces iron from iron(III) oxide; A is oxidised; iron is reduced.
Show mark scheme and worked solution
Marking points
M1 (a) · 1 mark · Correctly interprets that a reaction means a metal is more reactive than iron.
A1 (a) · 1 mark · Arranges reactivity: A > C > B = D (accept B and D in either order for equal non-reactivity).
M2 (b) · 1 mark · Describes that A displaces iron from iron(III) oxide in a redox reaction.
B1 (b) · 1 mark · Identifies iron is reduced (Fe3+ to Fe); identifies A is oxidised (A to A oxide).
B2 (b) · 1 mark · States both oxidation and reduction or both metals' changes in oxidation state.
Worked solution
a) A shows the brightest reaction, so it is the most reactive. C gives a slower reaction but still forms metal, so it is less reactive than A but more than those that give no reaction. B and D show no reaction, so are least reactive (possibly similar to or less reactive than iron).
Order: A > C > B = D
b) Metal A reacts as follows:
Metal A is oxidised (loses electrons or gains oxygen) and forms A2O3. Iron(III) oxide is reduced: Fe3+ ions are reduced to Fe metal.