Question

What happens when a piece of Zinc metal is added to Copper sulphate solution?

Also, write the balanced chemical equation if the reaction occurs.

Answer 1

1. Displacement reactions

Chemical reactions in which a more reactive metal displaces a less reactive metal from its salt solution are called displacement reactions. The products of a displacement reaction are predicted from the reactivity series of the metals.

2. Reactivity series

The metals are arranged in the order of their reactivity with dilute acids and water in the reactivity series. Hydrogen is also placed in the series and is used as the reference. The metals above Hydrogen can displace Hydrogen from acid solution while metals Hydrogen can displace the metals below it.

Therefore, when a more reactive metal comes in contact with a solution of a less reactive metal, a displacement reaction occurs and the more reactive element remains in the solution. The less reactive metal remain in their elemental state.

3. Zinc in Copper sulphate solution

Zinc $\left(\mathrm{Zn}\right)$ is placed above hydrogen and copper $\left(\mathrm{Cu}\right)$ is placed below hydrogen in the reactivity series. Therefore, the reactivity of zinc is more than the reactivity of copper and zinc can displace Copper from its solution.

Zinc metal reacts with Copper sulphate $\left({\mathrm{CuSO}}_4\right)$ solution to form Zinc sulphate $\left({\mathrm{ZnSO}}_4\right)$. Copper (Cu) is deposited in its metallic form from the solution.

The balanced equation for the reaction is given below:

$$\begin{gathered} \mathrm{Zn}\left(\mathrm{s}\right)+{\mathrm{CuSO}}_4\left(\mathrm{aq}\right)\to {\mathrm{ZnSO}}_4\left(\mathrm{aq}\right)+\mathrm{Cu}\left(\mathrm{s}\right) \\ \left(\mathrm{Zinc}\right)(\mathrm{Copper}(\mathrm{Zinc}\left(\mathrm{Copper}\right) \\ \mathrm{sulphate})\mathrm{sulphate}) \end{gathered}$$