Question

Both Zinc sulphate and Lead nitrate are colorless solid substances. Write the chemical reaction used to identify them.

Answer 1

Part-1 Zinc sulphate and Lead nitrate can be identified when they react with Ammonium hydroxide $\left({\mathrm{NH}}_4\mathrm{OH}\right)$

• When Zinc sulphate reacts with Ammonium hydroxide$\left({\mathrm{NH}}_4\mathrm{OH}\right)$, a white gelatinous precipitate is formed, which is solubilized in the excess of Ammonium hydroxide.
• When Lead nitrate reacts with Ammonium hydroxide$\left({\mathrm{NH}}_4\mathrm{OH}\right)$, a white precipitate is formed, which is insoluble in the excess of Ammonium hydroxide.

Part-2 Lead nitrate and Zinc sulphate reaction with Ammonium hydroxide.

$$\begin{gathered} \left(\mathrm{a}\right){\mathrm{ZnSO}}_4\left(\mathrm{aq}\right)+2{\mathrm{NH}}_4\mathrm{OH}\left(\mathrm{aq}\right)\to \mathrm{Zn}{\left(\mathrm{OH}\right)}_2\left(\mathrm{ppt}\right)\left(\mathrm{s}\right)+{\left({\mathrm{NH}}_4\right)}_2{\mathrm{SO}}_4\left(\mathrm{aq}\right) \\ (\mathrm{Zinc}\mathrm{sulphate})(\mathrm{Ammonium}\mathrm{hydroxide})(\mathrm{Zinc}\mathrm{hydroxide})(\mathrm{Ammonium}\mathrm{sulphate}) \\ \mathrm{Zn}{\left(\mathrm{OH}\right)}_2\left(\mathrm{s}\right)+{\left({\mathrm{NH}}_4\right)}_2{\mathrm{SO}}_4\left(\mathrm{aq}\right)+2{\mathrm{NH}}_4\mathrm{OH}\left(\mathrm{aq}\right)\to \left[\mathrm{Zn}{\left({\mathrm{NH}}_3\right)}_4\right]{\mathrm{SO}}_4\left(\mathrm{s}\right)+{\mathrm{H}}_2\mathrm{O}\left(\mathrm{l}\right) \\ (\mathrm{Zinc}\mathrm{hydroxide})(\mathrm{Ammonium}\mathrm{sulphate})(\mathrm{Ammonium}\mathrm{hydroxide})(\mathrm{Tetraammine}\mathrm{zinc}(\mathrm{II})\mathrm{sulphate})\mathrm{Water} \\ \left(\mathrm{b}\right)\mathrm{Pb}{\left({\mathrm{NO}}_3\right)}_2\left(\mathrm{aq}\right)+2{\mathrm{NH}}_4\mathrm{OH}\left(\mathrm{aq}\right)\to \mathrm{Pb}{\left(\mathrm{OH}\right)}_2\left(\mathrm{ppt}\right)\left(\mathrm{s}\right)+2{\mathrm{NH}}_4{\left(\mathrm{NO}\right)}_3\left(\mathrm{aq}\right) \\ (\mathrm{Lead}\mathrm{nitrate})(\mathrm{Ammonium}\mathrm{hydroxide})(\mathrm{Lead}\mathrm{hydroxide})(\mathrm{Ammonium}\mathrm{nitrate}) \end{gathered}$$