Metal Displacement Reactions (Edexcel IGCSE Chemistry: Double Science)

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Metal displacement reactions

  • The reactivity of metals decreases going down the reactivity series.
  • This means that a more reactive metal will displace a less reactive metal from its compounds
  • Two examples are:
    • Reacting a metal with a metal oxide (by heating)
    • Reacting a metal with an aqueous solution of a metal compound

  • For example it is possible to reduce copper(II) oxide by heating it with zinc.
  • The reducing agent in the reaction is zinc:

Zn    +     CuO    →    ZnO    +    Cu

zinc + copper(II) oxide → zinc oxide + copper

Metal oxide displacement table

Mixture Products Equation for Reaction 
 Iron(III) oxide and aluminium - thermite reaction  Iron and aluminium oxide  Fe2O3 + 2Al  → 2Fe + Al2O3
 Sodium oxide and magnesium  No reaction as sodium is above magnesium -----
 Silver oxide and copper  Silver and copper(II) oxide  Ag2O + Cu → 2Ag + CuO
 Zinc oxide and calcium  Zinc and calcium oxide  ZnO + Ca → Zn + CaO
 Lead(II) oxide and silver  No reaction as lead is more reactive than silver ------
 Iron nail and copper(II) chloride  Copper and iron(II) chloride  Fe + CuCl2 → FeCl2 + Cu




Displacement reactions between metals & aqueous solutions of metal salts

  • The reactivity between two metals can be compared using displacement reactions in salt solutions of one of the metals
  • This is easily seen as the more reactive metal slowly disappears from the solution, displacing the less reactive metal
  • For example, magnesium is a reactive metal and can displace copper from copper(II)sulfate solution:

Mg + CuSO4→ MgSO4 + Cu

  • The blue colour of the CuSO4 solution fades as colourless magnesium sulfate solution is formed
  • Copper coats the surface of the magnesium and also forms solid metal which falls to the bottom of the beaker

Displacement reaction between magnesium and copper(II) sulfate

Magnesium-copper displacement, IGCSE & GCSE Chemistry revision notes

Diagram showing the colour change when magnesium displaces copper from copper(II) sulfate

Other displacement reactions

Metal solutions displacement table

Mixture Products Equation for Reaction
 Magnesium and iron(II) sulfate  Magnesium sulfate and iron  Mg + FeSO4 → MgSO4 + Fe
 Zinc and sodium chloride  No reaction as sodium is above zinc  ------
 Lead and silver nitrate  Lead(II) nitrate and silver  Pb + AgNO3 → Pb(NO3)2 + Ag
 Copper and calcium chloride  No reaction as calcium is above copper  -------
 Iron and copper(II) sulfate  Iron(II) sulfate and copper   Fe + CuSO4 → FeSO4 + Cu

Examiner Tip

Displacement reactions occur when the solid metal is more reactive than the metal that is in the compound.

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Stewart

Author: Stewart

Expertise: Chemistry Lead

Stewart has been an enthusiastic GCSE, IGCSE, A Level and IB teacher for more than 30 years in the UK as well as overseas, and has also been an examiner for IB and A Level. As a long-standing Head of Science, Stewart brings a wealth of experience to creating Exam Questions and revision materials for Save My Exams. Stewart specialises in Chemistry, but has also taught Physics and Environmental Systems and Societies.