Question

What is aqua regia?

Answer 1

Hint : Aqua regia is a highly corrosive mixture of nitric and hydrochloric acids that is employed as an etchant, in various analytical chemical operations, and in gold refinement. Gold, platinum, and palladium dissolve in aqua regia, but not the other noble metals.

Complete Step By Step Answer:
Aqua regia (also known as "regal water" or "royal water") is a solution of nitric acid and hydrochloric acid in a $ 1:3 $ molar ratio. Aqua regia is a seething yellow-orange (occasionally red) liquid named by alchemists for its ability to dissolve the noble metals gold and platinum, but not all metals.
It's often used in microfabrication and microelectronics labs to remove precious metals like gold, platinum, and palladium from substrates. Glassware can also be washed with aqua regia to remove only trace amounts of organic contaminants. Aqua regia solutions are extremely corrosive and should be handled with utmost caution to avoid explosions or skin burns.

Additional Information:
Storage:- Aqua regia should not be stored. Due to oxidation of its reactive components, aqua regia quickly loses its efficacy. For each use, make a new solution. Excess solutions should be neutralised with sodium bicarbonate and flushed with copious amounts of water before being disposed of down the drain.
Disposal:- Aqua regia can be disposed of by carefully neutralising it before pouring it down the sink, though local restrictions may differ. If dissolved metals are present, the neutralised solution should be collected and disposed of.

Note :
One query may arise in mind that, What distinguishes aqua regia as royal? Aqua regia may dissolve a variety of metals that are generally difficult to dissolve, including platinum, silver, and gold. Because these metals are referred to as noble metals, the solution that can dissolve them is referred to as "royal water." Aqua regia is a mixture of two acids, hydrochloric acid $ \left( {HCl} \right) $ and nitric acid, rather than a single chemical $ \left( {HN{O_3}} \right) $ . The product is more potent than the sum of its parts in the case of aqua regia, which is why it is so useful.