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More reactive metals displace less reactive metals from their compounds. For example, magnesium is more reactive than copper. It displaces copper from copper(II) sulfate solution.

magnesium + copper(II) sulfate → magnesium sulfate + copper

Mg(s) + CuSO₄(aq) → MgSO₄(aq) + Cu(s)

In this displacement reaction:

• the copper coats the magnesium
• the solution’s blue colour fades as blue copper(II) sulfate is replaced by colourless magnesium sulfate solution.