Question

Gold Sol can be prepared by

Answer 1

Preparation of Gold sol

1. The gold solution can be prepared by reducing Gold(III) chloride (${\mathrm{AuCl}}_3$) with the formalin solution.
2. The chemical reaction involved in this process is

$\underset{\mathrm{Gold}\left(\mathrm{III}\right)\mathrm{Chloride}}{2{\mathrm{AuCl}}_3\left(\mathrm{s}\right)}+\underset{\mathrm{Formaldehyde}}{3\mathrm{HCHO}\left(\mathrm{aq}\right)}+\underset{\mathrm{Water}}{3{\mathrm{H}}_2\mathrm{O}\left(\mathrm{l}\right)}\stackrel{\mathrm{Reduction}}{\to }\underset{\mathrm{Solid}\mathrm{sol}}{2\mathrm{Au}\left(\mathrm{s}\right)}+\underset{\mathrm{Formic}\mathrm{acid}}{3\mathrm{HCOOH}\left(\mathrm{aq}\right)}+\underset{\mathrm{Hydrochloric}\mathrm{acid}}{6\mathrm{HCl}\left(\mathrm{aq}\right)}$

Therefore, gold Sol can be prepared by reduction of Gold(III) Chloride (${\mathrm{AuCl}}_3$).