Aqua regia, which is a mixture of two acids, will dissolve gold. Aqua regia is a mixture of concentrated nitric acid (HNO3) and concentrated hydrochloric acid (HCl), usually in a 1 to 3 ratio respectively. Aqua regia is one of the few acids that will dissolve both gold and platinum as well as other metals. Interestingly, neither hydrochloric acid nor nitric acid alone will dissolve gold, but together, they will!
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