Gold parting instead of copper. One part pure gold is alloyed with three parts Sterling silver (inquarting). The resulting six karat (6K) gold can then be parted with dilute nitric acid (one part 68-70% nitric acid to one part DISTILLED water). With the karat gold this low (6K), and over medium high heat, the dilute nitric acid will dissolve the Sterling silver (and other base metals in the karat gold) starting on the outside surface of the 6K gold alloy, working its way into the gold alloy, forming a honeycomb structure as it works its way into the metals. Since nitric acid
Acid–base reaction the Brønsted-Lowry model, the solvent does not necessarily have to be water that is required by the Arrhenius Acid-Base model. For example, consider what happens when acetic acid, CHCOOH, dissolves in liquid ammonia. An H ion is removed from acetic acid, forming its conjugate base, the acetate ion, CHCOO. The addition of an H ion to an ammonia molecule of the solvent creates its conjugate acid, the ammonium ion, . The Brønsted–Lowry model calls hydrogen-containing substances (like HCl) acids. Thus, some substances, which many chemists considered to be acids, such as SO or BCl, are excluded from this classification due