Physical Properties
Colorless, monoclinic crystal; density 2.276 g/cm3; decomposes on heating; soluble in water (decomposes); also soluble in acid; insoluble in alcohol and liquid ammonia.
Uses
Ammonium molybdates are used to prepare high purity grade molybdenum metal powder, sheet, or wire; for colorimetric analysis of phosphates and arsenates; for decorating ceramics; and as catalysts.
Preparation
Ammonium molybdate is prepared by treating molybdenum oxide with excess ammonia in an aqueous solution. The crystals are obtained after evaporation of water.
MoO3 + 2NH3 + H2O → (NH4)2MoO4
Reactions
Decomposes on heating or on treatment with alkalies; reacts with lead chloride and other metal salts to form their metal molybdates:
(NH4)2MoO4 + PbCl2 → PbMoO4 + 2NH4Cl
Reacts with phosphates or arsenates to form ammonium phosphomolybdate (NH4)3PO4•12MoO3, or ammonium arsenomolybdate, (NH4)3AsO4•12MoO3.
Chemical Properties
white powder(s); obtained by crystallization from a solution of MoO3 containing excess NH3; used as a high purity source for the preparation of Mo metal [KIR8l] [ALF93]
Physical properties
Colorless, monoclinic crystal; density 2.276 g/cm
3; decomposes on heating; soluble in water (decomposes); also soluble in acid; insoluble in alcohol and liquid ammonia.
Uses
Ammonium molybdate (di) is used as pigments, agricultural fertilizer, color lakes and fabric fire retardant agent. It is also used as a raw material for the production of molybdenum wire, ceramic glazes and other molybdenum compounds. Further, it is used in photography, ceramics and paints. It is also used reagent for analysis as well as in the determination of phosphorus in analytical chemistry. In addition, it is used as a catalyst in the petrochemical industry.
Flammability and Explosibility
Not classified
