Metal Displacement Reactions (Edexcel IGCSE Chemistry (Modular))
Revision Note
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
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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