Q30 / 160 · TS EAMCET 2018 (04 May Shift 2) · Chemistry
What is the final chemical form of Gold (Au) when it is dissolved in aqua-regia?
- A$\mathrm{Au}$
- B$\mathrm{AuCl}$
- C$\mathrm{AuCl}_2$
- Correct answerD$\left[\mathrm{AuCl}_4\right]^{-}$
Solution
When gold (Au) dissolved in aqua-regia, it forms chloroauric $\left(\mathrm{HAuCl}_4\right)$ ion. It will react very slowly with chlorin gas at room temperature to form gold chloride. We know that aqua-regia is
$$
\mathrm{Au}+\mathrm{HCl}+\mathrm{HNO}_3 \stackrel{3 \mathrm{Cl}+\mathrm{HNO}_3}{\left.\mathrm{HuCl}_4\right]^{-}}
$$
Hence, the correct answer is option: 'D'.