A student tests three metals — magnesium, copper, and tin — by placing each one separately into dilute hydrochloric acid. Magnesium reacts vigorously, tin reacts slowly, and copper shows no reaction. Describe what these observations tell us about the relative positions of these three metals in the reactivity series, and explain why copper does not react with dilute hydrochloric acid.

Cambridge International IGCSE Chemistry (0620) — 9.4 Reactivity series · Describe and Explain · 4 marks · View as Markdown

Written & reviewed by James Millett — Biology (Imperial College London), PGCE Science (University of Cambridge).

Model answer (4 marks)

Magnesium is above tin in the reactivity series, so it reacts more vigorously with acid.
Tin is above copper, so it reacts, but more slowly.
Thus the relative order from most to least reactive is magnesium, tin, copper.
Copper is below hydrogen in the series, so it cannot displace hydrogen from dilute hydrochloric acid and therefore shows no reaction.

Examiner tips

  • Use the order magnesium > tin > copper explicitly. Explain copper’s lack of reaction by stating it is below hydrogen. Show the link between reactivity and ability to displace H⁺.

Common mistakes

  • Saying copper reacts with acid but too slowly. Forgetting to mention hydrogen’s position. Mixing up the order of magnesium and tin.

Mark scheme (4 marks)

  1. Magnesium is more reactive than tin / magnesium is above tin in the reactivity series
  2. Tin is more reactive than copper / tin is above copper in the reactivity series
  3. The order (from most to least reactive) is magnesium, tin, copper / correct relative order stated
  4. Copper cannot displace / react with hydrogen because copper is below hydrogen in the reactivity series / copper is less reactive than hydrogen

Key terms in this question

reactivity series · dilute hydrochloric acid

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