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
Acid-base extraction pH range. The order of the step is not important and the process can be repeated to increase the separation. However, it is often convenient to have the compound dissolved in the organic phase after the last step, so that the evaporation of the solvent yields the product. The procedure works only for acids and bases with a large difference in solubility between their charged and their uncharged form. The procedure does not work for: Alternatives to acid-base extraction including: Acid-base extraction Acid-base extraction is a procedure using sequential liquid–liquid extractions to purify acids and bases from mixtures based on