Metal Displacement Reactions (Edexcel IGCSE Chemistry (Modular))

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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

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

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 CuSO₄solution 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

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

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

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

the (exam) results speak for themselves:

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