Question

Give the reaction for the formation of Aqua Regia.

Answer 1

1. Aqua Regia is a mixture of concentrated ${\mathrm{HNO}}_3$ and concentrated $\mathrm{HCl}$.
2. The Ratio for these acids is 1:3 by volume.
3. Another name of Aqua Regia is royal water.
4. It can be used to dissolve gold $\left(\mathrm{Au}\right)$ and platinum $\left(\mathrm{Pt}\right)$ in jewellery.
5. It can dissolve all metals except silver $\left(\mathrm{Ag}\right)$.

Reaction for the formation of Aqua Regia:

$$\begin{gathered} {\mathrm{HNO}}_3\left(\mathrm{aq}\right)+3\mathrm{HCl}\left(\mathrm{aq}\right)\to \mathrm{NOCl}\left(\mathrm{g}\right)+2{\mathrm{H}}_2\mathrm{O}\left(\mathrm{l}\right)+{\mathrm{Cl}}_2\left(\mathrm{g}\right) \\ \mathrm{nitric}\mathrm{acid}\mathrm{hydrochloric}\mathrm{acid}\mathrm{nitrosyl}\mathrm{chloride}\mathrm{water}\mathrm{chlorine} \end{gathered}$$

Here in this reaction, nitric acid oxidizes the hydrochloric acid to give their corresponding chlorine.