Question

Give one example of the double displacement reaction in which

(iv) a white precipitate is formed

Answer 1

1. Double displacement reaction

A double displacement reaction is a reaction in which there occurs a replacement of the anions and cations of two compounds (reactants).

2. Example of double displacement reaction where a white precipitate is formed

The double displacement reaction for the formation of a white precipitate is given below.

$$\begin{gathered} {\mathrm{BaCl}}_2\left(\mathrm{aq}\right)+{\mathrm{Na}}_2{\mathrm{SO}}_4\left(\mathrm{aq}\right)\to {\mathrm{BaSO}}_4\left(\mathrm{aq}\right)+2\mathrm{NaCl}\left(\mathrm{aq}\right) \\ \mathrm{Barium}\mathrm{Sodium}\mathrm{Barium}\mathrm{Sodium} \\ \mathrm{chloride}\mathrm{sulphate}\mathrm{sulphate}\mathrm{chloride} \end{gathered}$$
Barium chloride $\left({\mathrm{BaCl}}_2\right)$ and Sodium sulphate $\left({\mathrm{Na}}_2{\mathrm{SO}}_4\right)$ undergo a double displacement reaction to give Sodium chloride and Barium sulphate $\left({\mathrm{BaSO}}_4\right)$ which appears as a white precipitate.