Question

What would you observe in the following case:

A few drops of dilute hydrochloric acid are added to the silver nitrate solution followed by addition of ammonium hydroxide solution.

Answer 1

Step-I

When a few drops of dilute Hydrochloric acid $\left(\mathrm{HCl}\right)$ are added to silver nitrate solution $\left({\mathrm{AgNO}}_3\right)$ then a white precipitate of silver chloride $\left(\mathrm{AgCl}\right)$ is formed.

$$\begin{gathered} {\mathrm{AgNO}}_3\left(\mathrm{aq}\right)+\mathrm{HCl}\left(\mathrm{aq}\right)\to \mathrm{AgCl}\left(\mathrm{s}\right)+{\mathrm{HNO}}_3\left(\mathrm{aq}\right) \\ (\mathrm{silver}(\mathrm{hydrochloric}(\mathrm{silver}(\mathrm{nitric} \\ \mathrm{nitrate})\mathrm{acid})\mathrm{chloride})\mathrm{acid}) \end{gathered}$$

Here in this reaction, silver nitrate is reacting with hydrochloric acid, then these reactants are giving silver chloride and nitric acid as the product.

Step-II

The white precipitates that are formed will dissolve in ammonium hydroxide $\left({\mathrm{NH}}_4\mathrm{OH}\right)$ and form a stable complex of diammine silver chloride $\left[\mathrm{Ag}{\left({\mathrm{NH}}_3\right)}_2\mathrm{Cl}\right]$

$$\begin{gathered} \mathrm{AgCl}\left(\mathrm{s}\right)+2{\mathrm{NH}}_4\mathrm{OH}\left(\mathrm{l}\right)\to \left[\mathrm{Ag}{\left({\mathrm{NH}}_3\right)}_2\mathrm{Cl}\right]\left(\mathrm{s}\right)+2{\mathrm{H}}_2\mathrm{O}\left(\mathrm{l}\right) \\ (\mathrm{silver}(\mathrm{ammonium}(\mathrm{diammine}\mathrm{silver}(\mathrm{water}\left) \\ \mathrm{chloride}\right)\mathrm{hydroxide})\mathrm{chloride}) \end{gathered}$$

Here in this reaction, silver chloride is reacting with ammonium hydroxide and produces diamine silver chloride and water also. The white precipitates that are formed are insoluble in water but soluble in ammonium hydroxide