Gold with hydrofluoric, hydrochloric, hydrobromic, hydriodic, sulfuric, or nitric acid. It does react with selenic acid, and is dissolved by aqua regia, a 1:3 mixture of nitric acid and hydrochloric acid. Nitric acid oxidizes the metal to +3 ions, but only in minute amounts, typically undetectable in the pure acid because of the chemical equilibrium of the reaction. However, the ions are removed from the equilibrium by hydrochloric acid, forming AuCl ions, or chloroauric acid, thereby enabling further oxidation. Gold is similarly unaffected by most bases. It does not react with aqueous, solid, or molten sodium or potassium hydroxide. It does
Methanesulfonic acid Methanesulfonic acid Methanesulfonic acid (MsOH) is a colorless liquid with the chemical formula CHSOH. It is the simplest of the alkylsulfonic acids. Salts and esters of methanesulfonic acid are known as mesylates (or methanesulfonates, as in ethyl methanesulfonate). It is hygroscopic in its concentrated form. Methanesulfonic acid may be considered an intermediate compound between sulfuric acid (HSO), and methylsulfonylmethane ((CH)SO), effectively replacing an –OH group with a –CH group at each step. This pattern can extend no further in either direction without breaking down the –SO– group. Methanesulfonic acid can dissolve a wide range of metal salts, many of them