Question

What is the final chemical form of Gold (Au) when it is dissolved in aqua-regia?

• A. $Au$
• B. $AuCl$
• C. $AuCl _{2}$
• D. $\left[ AuCl _{4}\right]^{-}$

Answer 1

Answer: (D)

When gold (Au) dissolved in aqua-regia, it forms chloroauric $(HAuCl _{4} ) $ ion. It will react very slowly with chlorin gas at room temperature to form gold chloride. We know that aqua-regia is