Silver carbide, Ag₂C₂

Excess of an aqueous solution of acetylene precipitates from ammoniacal silver nitrate the greyish-yellow Silver carbide, Ag₂C₂. On exposure to light it darkens rapidly. When heated, the dry salt explodes. With hydrochloric acid it evolves acetylene, and with nitric acid it undergoes complete decomposition. Water causes hydrolysis to some extent, with production of Silver monoxide. Agitation with sodium-chloride solution causes similar hydrolysis, the solution becoming strongly alkaline. The heat of formation from the elements is given by Berthelot as -87.15 Cal. It forms a series of double salts with the halides, sulphate, and nitrate of silver.