Silver carbonate, Ag₂CO₃

When the equivalent proportion of potassium carbonate or potassium hydrogen carbonate is added to a solution of Silver nitrate, silver carbonate, Ag₂CO₃, is precipitated as a yellow powder. Addition of excess of potassium carbonate causes simultaneous precipitation of a proportion of Silver monoxide. Pure silver carbonate is white, but is sensitive to light. At 200° C. it decomposes with evolution of carbon dioxide. Its heat of formation is 120.8 Cal. Silver nitrate precipitates from a hot, concentrated solution of potassium carbonate a double salt of the formula Ag₂CO₃,K₂CO₃. A crystalline double compound with ammonia of the formula Ag₂CO₃,4NH₃,H₂O is produced by the spontaneous evaporation in air of an ammoniacal solution of silver oxide. Under the influence of sunlight the crystals become black; and on exposure to air they lose water and ammonia, yielding silver carbonate.