March 19 2012 2 19 /03 /March /2012 17:56
Silver, being a relatively inert metal, does not dissolve in hydrochloric or sulfuric acid. Even if it did, it would form the insoluble silver chloride or the slightly soluble silver sulfate. Here are some of my experiences with dissolving silver.
Aqua regia: Silver is insoluble in aqua regia because of the presence of chloride.
Nitric acid: This is the best solvent for silver metal. Silver dissolves easily in nitric acid, releasing nitrogen dioxide fumes and forming a colorless solution of silver nitrate. Here is a video by NurdRage on YouTube demonstrating the process.
Acetic acid and hydrogen peroxide: Although silver acetate is soluble, it barely passes as a soluble salt (where soluble is defined as excess of 1 g/100 mL dissolving, silver acetate is 1.02 g). Ordinary silver dissolves with difficulty in a 1:1 mixture of 5% acetic acid and 3% hydrogen peroxide. However, "anodizing" the silver in a salt water bath corrodes the surface, allowing it to dissolve in the aqueous solution. The solution is cloudy as the result of residual chloride ions in the metal from the "anodizing". The hydrogen peroxide decomposes as the silver dissolves, allowing bubbles to be used as an indicator of dissolution. This solution can be used to synthesize basic silver compounds. It might be non-ideal for the growing of a silver tree, as excess reagents in the solution can cause redissolution of the silver crystals from the copper wire. More concentrated reagents should be better.