Question

State whether a displacement reaction will occur if the following are mixed. Give reasons. Give the reaction.
(a) copper sulphate and zinc
(b) copper sulphate and iron
(c) zinc sulphate and copper
(d) zinc sulphate and iron
(e) iron sulphate and zinc
(f) iron sulphate and copper

Answer 1

Displacement reaction is a reaction in which a one more reactive metal displaces a less reactive metal from its salt solution. They can displace other metals, which are below them in the reactivity series. Let us see if a displacement reaction takes place in the following reactions.

(a) Copper sulphate and zinc: Zinc is more reactive than copper and is placed at the top of the reactivity series above copper. Thus, a displacement reaction occurs as zinc displaces copper from copper sulphate solution.

$\underset{\mathrm{Zinc}}{\mathrm{Zn}}+\underset{\mathrm{Copper}\mathrm{sulphate}}{{\mathrm{CuSO}}_4}\to \underset{\mathrm{Zinc}\mathrm{sulphate}}{{\mathrm{ZnSO}}_4}+\underset{\mathrm{Copper}}{\mathrm{Cu}}$

(b) Copper sulphate and iron- Iron is more reactive than copper and is placed at the top of the reactivity series above copper. Therefore, a displacement reaction occurs as iron displaces copper from copper sulphate solution.

$\underset{\mathrm{Iron}}{\mathrm{Fe}}+\underset{\mathrm{Copper}\mathrm{sulphate}}{{\mathrm{CuSO}}_4}\to \underset{\mathrm{Ferrous}\mathrm{sulphate}}{{\mathrm{FeSO}}_4}+\underset{\mathrm{Copper}}{\mathrm{Cu}}$

(c) Zinc sulphate and copper - Copper being less reactive than zinc, is placed at the bottom of the reactivity series below zinc. Therefore, a displacement reaction does not take place as copper cannot displace zinc from zinc sulphate solution

$\underset{\mathrm{Copper}}{\mathrm{Cu}}+\underset{\mathrm{Zinc}\mathrm{sulphate}}{{\mathrm{ZnSO}}_4}\to \mathrm{No}\mathrm{reaction}$

(d) Zinc sulphate and iron - Iron being less reactive than zinc, is placed below zinc, in the reactivity series. Therefore, a displacement reaction does not take place as iron cannot displace zinc from zinc sulphate solution.

$\underset{\mathrm{Iron}}{\mathrm{Fe}}+\underset{\mathrm{Zinc}\mathrm{sulphate}}{{\mathrm{ZnSO}}_4}\to \mathrm{No}\mathrm{reaction}$

(e) Iron sulphate and zinc - Zinc is more reactive than iron and is placed above iron in the reactivity series. Therefore, a displacement reaction occurs as zinc displaces iron from iron sulphate solution.

$\underset{\mathrm{Zinc}}{\mathrm{Zn}}+\underset{\mathrm{Ferrous}\mathrm{sulphate}}{{\mathrm{FeSO}}_4}\to \underset{\mathrm{Zinc}\mathrm{sulphate}}{{\mathrm{ZnSO}}_4}+\underset{\mathrm{Iron}}{\mathrm{Fe}}$

(f) Iron sulphate and copper - Copper being less reactive than iron, is placed at the bottom of the reactivity series, below iron. Therefore, a displacement reaction does not take place as copper cannot displace iron from iron sulphate solution.

$\underset{\mathrm{Copper}}{\mathrm{Cu}}+\underset{\mathrm{Iron}\mathrm{sulphate}}{{\mathrm{FeSO}}_4}\to \mathrm{No}\mathrm{reaction}$