Question

What will you observe when caustic soda solution is added to a solution of ferric sulphate.

Answer 1

When caustic soda solution is added to a solution of ferric sulphate a reddish-brown precipitate of Fe(OH)₃ is formed.

$$\begin{gathered} {\mathrm{Fe}}_2{\left({\mathrm{SO}}_4\right)}_3\left(\mathrm{s}\right)+6\mathrm{NaOH}\left(\mathrm{aq}\right)\to 2\mathrm{Fe}{\left(\mathrm{OH}\right)}_3\left(\mathrm{s}\right)+3{\mathrm{Na}}_2{\mathrm{SO}}_4\left(\mathrm{s}\right) \\ \mathrm{Ferric}\mathrm{sulphate}\mathrm{Sodium}\mathrm{hydroxide}\mathrm{Ferric}\mathrm{hydroxide}\mathrm{Sodim}\mathrm{sulphate} \end{gathered}$$