Displacement reactions involving metal oxides

2 marks · Hard

Copper(II) oxide reacts with a solid element X when heated, producing copper metal and a white solid. Element X cannot displace magnesium from magnesium oxide.

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Element X is zinc; zinc can displace copper from its oxide but not magnesium.

Also accept: Zinc is element X; zinc is above copper but below magnesium in the reactivity series.

Common mistakes: Stating X is magnesium or aluminium.; Saying copper is more reactive than zinc.

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Marking points

M1 · 1 mark · Correctly identifies the pattern of reactivity: X must be between copper and magnesium in the reactivity series.

A1 · 1 mark · States or names zinc as element X, with the correct justification based on reactivity series.

Worked solution

Since copper(II) oxide reacts with X to form copper, X must be more reactive than copper. But X cannot displace magnesium from its oxide, so X must be less reactive than magnesium.

Looking at the reactivity series: magnesium > zinc > copper.

Therefore, element X is zinc.