Aqua regia is able to dissolve gold and platinum because it is a highly corrosive and powerful oxidizing agent. The combination of hydrochloric acid and nitric acid creates a solution capable of breaking down the noble metal structures and oxidizing them, allowing them to dissolve.
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Aqua regia can dissolve gold and platinum due to its strong oxidizing and acidic properties. The mixture of concentrated nitric acid (HNO₃) and concentrated hydrochloric acid (HCl) in aqua regia produces a highly reactive and corrosive solution. Nitric acid provides the strong oxidizing agent, nitrosyl chloride (NOCl), which breaks down the protective oxide layer on noble metals like gold and platinum. Hydrochloric acid then forms soluble metal chloride complexes, allowing the metals to dissolve. The combined action of oxidation and complexation enables aqua regia to effectively dissolve gold and platinum, making it a powerful solvent for these resistant metals.