Minerals, Metals, and Other Materials

Man-Made Products

What is aqua regia?

Aqua regia, also known as nitrohydrochloric acid, is a mixture of one part concentrated nitric acid and three parts concentrated hydrochloric acid. The chemical reaction between the acids makes it possible to dissolve all metals except silver. The reaction of metals with nitrohydrochloric acid typically involves oxidation of the metals to a metallic ion and the reduction of the nitric acid to nitric oxide. The term comes from Latin and means “royal water.” It was named by the alchemists for its ability to dissolve gold and platinum, which were called the “noble metals.”


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