Silver sulphate, Ag₂SO₄

The Silver sulphate, Ag₂SO₄ is produced by dissolving the metal in sulphuric acid, and by the action of this acid on the nitrate. It forms white, rhombic crystals, isomorphous with those of the corresponding sodium salt, and melting at low red heat. Its density is 5.45. The solubility of silver sulphate in water at various temperatures has been only partially investigated. At 14.5° C., 100 grams of saturated solution contain 0.730 gram of silver sulphate; at 25° C. the solubility is 0.0267 gram-molecule per litre of water. Its heat of formation from the metal, oxygen, and sulphur dioxide is 96.20 Cal.

When the sulphate is heated to fusion in a current of hydrogen chloride, it is converted completely into chloride:

Ag₂SO₄ + 2HCl = 2AgCl + H₂SO₄. Heating with Silver sulphide causes partial reduction to metallic silver: Ag₂SO₄ + Ag₂S = 4Ag + 2SO₂.

From the solution in dilute sulphuric acid three acid salts have been obtained: AgHSO₄, pale yellow prisms; 2Ag₂O,5SO₃,5H₂O, lustrous laminae; and Ag₂O,4SO₃,5H₂O, colourless prisms. The saturated solution in ammonium hydroxide yields tetragonal crystals of the formula Ag₂SO₄,4NH₃. The dry sulphate absorbs ammonia, forming a compound Ag₂SO₄,2NH₃.