Chemistry Form 5: Chapter 3 - Redox Reaction in Displacement of Metal

Reactivity Series of metals

Displacement of metals from solution is a redox reaction whereby a less reactive metal ion is displaced from its salt solution by a more reactive metal. As a result, the less reactive metal ion is deposited as a solid metal while the more reactive metal dissolves in the solution. The general formula for a displacement reaction is: M (s) + Xn+ (aq)  ----->   Mn+ (aq) + X (s) where metal M is the more reactive than metal X.

Most reactive K Na Ca Mg Al Zn Fe Pb [H] Cu Ag Least reactive

Example of displacement reaction:

Fe (s) + CuSO₄ (aq)     ----->     FeSO₄ (aq) + Cu (s)

Iron displaces copper from the solution because it is more reactive than copper metal. Iron, being more reactive, loses its electrons readily. The electrons are transferred from the iron atoms to the copper(II) ions in the solution. Copper(II) ions are reduced to copper metal and iron atoms become oxidised to iron (II) ions. Iron acts as reducing agent whereas copper (II) ions act as a oxidising agent. 

Oxidation reaction:     Fe (s)     ----->     Fe²⁺ (aq) + 2e^-
Reduction reaction:    Cu²⁺ (aq) + 2e^-     ----->     Cu (s)
Overall Redox reaction:   Fe (s) + Cu²⁺ (aq)     ----->   Fe²⁺ (aq) + Cu (s)

Click on the diagram below to play!