Question

Identify the acid which matches the following description.

The acid on mixing with Silver nitrate solution produces a white precipitate which is soluble in excess Ammonium hydroxide.

Answer 1

• Hydrochloric acid is an acid that contains Chloride ions.
• When Silver nitrate is added to an acidic solution, Silver chloride is formed.
• The reaction between Hydrochloric acid and Silver nitrate is given below.
  $$\begin{gathered} {\mathrm{AgNO}}_3\left(aq\right)+\mathrm{HCl}\left(aq\right)\to \mathrm{AgCl}\left(s\right)+{\mathrm{HNO}}_3\left(aq\right) \\ \mathrm{Silver}\mathrm{Hydrochloric}\mathrm{Silver}\mathrm{Nitric} \\ \mathrm{nitrate}\mathrm{acid}\mathrm{nitrate}\mathrm{acid} \end{gathered}$$
• The precipitate here obtained is Silver chloride and it is soluble in excess Ammonium hydroxide (${\mathbf{NH}}_{\mathbf{4}}\mathbf{OH}$) by forming a complex Diamine silver chloride.
  $$\begin{gathered} \mathrm{AgCl}\left(s\right)+{\mathrm{NH}}_{4}O\mathrm{H}\left(aq\right)\to [\mathrm{Ag}{\left({\mathrm{NH}}_3\right)}_2{]}^{+}{\mathrm{Cl}}^{-}(aq) \\ \mathrm{Silver}\mathrm{Ammonium}\mathrm{Diam}\text{m}\mathrm{ine}\mathrm{silver} \\ \mathrm{nitrate}\mathrm{hydroxide}\mathrm{chloride} \end{gathered}$$
• Therefore, the acid is Hydrochloric acid which on mixing with Silver nitrate solution produces a white precipitate that is soluble in excess Ammonium hydroxide.