Question

The color of copper sulphate solution changes when an iron nail is dipped in it. State the giving chemical equation for the reaction involved. Write the name of reaction involved.

Answer 1

Reactivity series

Reactivity series is obtained by arranging the metals in the order of their reactivity with dilute acids. Reactivity series is used to predict the products of a displacement reaction. A reaction in which a more reactive displaces a less reactive metal is called displacement reaction. Therefore, if a more reactive metal is added to a solution of a less reactive metal, displacement reaction takes place and the more reactive metal moves into the soluion.

Iron nail dipped in Copper sulphate solution

Copper sulphate (CuSO₄) solution is blue in colour. Iron (Fe) is more reactive than Copper (Cu). Therefore, when Iron nails are added in Copper sulphate solution, it displaces Copper from the solution forming Ferrous sulphate (FeSO₄). The solution turns pale green and deposited Copper forms a thin brown layer on the surface of the iron nail.

The balanced equation for the reaction is:

$CuS{O}_4\left(aq\right)+Fe\left(s\right)\to FeS{O}_4\left(aq\right)+Cu\left(s\right)$

(Copper (Iron) (Ferrous (Copper)

sulphate) sulphate)

This reaction is an example for displacement reaction.