How Is Gold (III) Chloride Prepared?

Gold (III) chloride, also known as auric chloride or trichloroauric acid, can be prepared using different methods. One common method involves the reaction between gold metal and aqua regia, a mixture of hydrochloric acid and nitric acid:

Au + 3 HNO3 + 4 HCl → AuCl3 + 3 NO2 + 3 H2O

In this reaction, gold is oxidized by the nitric acid to form Au(III) ions, which then combine with the chloride ions from hydrochloric acid to form gold (III) chloride.

Alternatively, gold (III) chloride can also be prepared by reacting gold metal with chlorine gas:

2 Au + 3 Cl2 → 2 AuCl3

This method requires careful control of temperature and pressure to avoid formation of other gold compounds.

Another method involves the reaction between gold metal and hydrogen chloride gas at high temperatures:

2 Au + 6 HCl (g) → 2 AuCl3 + 3 H2(g)

This method is less commonly used because it requires high temperatures and may produce impurities.

After preparation, gold (III) chloride is typically purified by recrystallization or sublimation.