Cobalt Trimolybdate, CoMo3O10.10H2O, separates in rose- coloured needles on evaporating the solution obtained by boiling cobalt carbonate and molybdenum trioxide with water.
A number of complex salts have been prepared. By interaction of a cobaltous salt with ammonium paramolybdate, a light red crystalline compound, which may be formulated (NH4)3H7[Co(MoO4)6]5H2O, has been isolated. Several sodium compounds, probably of the same type, have been described. A series of green cobaltimolybdates, corresponding to the aluminium and chromium salts, has been obtained by oxidation with hydrogen peroxide or ammonium persulphate of an aqueous solution containing cobaltous acetate and ammonium paramolybdate, or by the action of a permolybdate on a cobaltous salt. The ammonium salt, 3(NH4)2O.CO2O3.12MoO3.20H2O, yields green rhombic crystals. The potassium salt, 3K2O.CO2O3.12MoO3.15H2O, is olive green, and only slightly soluble in water. The following salts have also been prepared: 2(NH4)2O.CO2O3.10MoO3.12H2O; 3K2O.CO2O3.10MoO3.11H2O; 3BaO.CO2O3.9MoO3.25H2O. |