Aqua regia, << AK wuh REE jee uh, >> is a mixture of nitric and hydrochloric acids. It is important in metallurgy and chemistry because it dissolves such metals as platinum and gold. Aqua regia is a Latin term meaning royal water. The mixture was given this name because it can dissolve gold, sometimes called the royal metal.
Aqua regia is made up of one part concentrated nitric acid to three parts of concentrated hydrochloric acid. Neither of these acids alone can dissolve gold or platinum. However, the chemical action between the acids forms nitrosyl chloride (NOCl) and chlorine gas, both powerful oxidizing agents. The presence of these oxidizers, plus excess hydrochloric acid, enables aqua regia to dissolve gold and platinum.
