| Simple molybdates of chromium, or Chromium Molybdates, have not been prepared, but a series of complex salts, analogous to those of aluminium, of the type 3R•2O.Cr2O3.12MoO3.aq., may be prepared by the action of chromic hydroxide on solutions of acid molybdates, or by boiling together solutions of chromic salts and paramolybdates and allowing to crystallise. The ammonium salt, 3(NH4)2O.Cr2O3.12MoO3.20H2O (or 26H2O), and the potassium salt, 3K2O.Cr2O3.12MoO3.20H2O, form rose-coloured crystals which are soluble in water, and whose solutions give precipitates with barium, bismuth, caesium, lead, mercurous, rubidium, and silver salts. All these insoluble compounds contain the complex Cr2O3.12MoO3, which appears to possess considerable stability. The free chromimolybdic acid 3H2O.Cr2O3.12MoO3.aq. is obtained by decomposing the mercurous salt with hydrochloric acid. Two barium salts, of composition 4BaO.Cr2O3.12MoO3. 15H2O and 5BaO.Cr2O3.12MoO3.16H2O, have been described. |