Question

Write the balanced chemical equation for the following reaction.

Gold added to aqua-regia.

Answer 1

Uses of Nitric acid:

Aqua-regia: It is a mixture of Nitric acid $\left({\mathrm{HNO}}_3\right)$ by 1 volume and Hydrochloric acid $\left(\mathrm{HCl}\right)$ by 3 volumes.

$2\mathrm{Au}\left(\mathrm{s}\right)+3{\mathrm{HNO}}_3\left(\mathrm{l}\right)+11\mathrm{HCl}\left(\mathrm{l}\right)\to 2{\mathrm{HAuCl}}_4\left(\mathrm{s}\right)+3\mathrm{NOCl}\left(\mathrm{g}\right)+6{\mathrm{H}}_2\mathrm{O}\left(\mathrm{l}\right)$

So by mixing Gold and Aqua regia, it produces a mixture of Chloroauric acid (HAuCl₄) and Nitrosyl chloride$\left(\mathrm{NOCl}\right)$.