Question

Write a short note:

Aqua Regia

Answer 1

• It is a freshly prepared mixture of two strong, concentrated acids: hydrochloric acid \[\ce{HCl}\] and nitric acid \[\ce{HNO3}\]. 
• The acids must be mixed in a specific volumetric ratio of 3:1 (three parts concentrated HCl to one part concentrated \[\ce{HNO3}\]).
• Neither of these acids can dissolve gold or platinum on its own. When combined, the nitric acid acts as a powerful oxidiser to dissolve tiny amounts of the metal, while the hydrochloric acid provides chloride ions that react with the dissolved metal ions, keeping them in a soluble state.
• It is primarily used in metallurgical processes to refine and purify high-quality gold, in analytical chemistry, and to clean stubborn metal deposits from laboratory glassware.