Tungstate Type

Tungstate Picture

Common tungstate have sodium tungstate (Na2WO4·2H2O), calcium tungstate (CaWO4), cobalt tungstate (CoWO4), cadmium tungstate (CdWO4), ferrous tungstate (FeWO4), ammonium tungstate [(NH4 ) 6W7O24·6H2O] and zinc tungstate (5ZnO·12WO3) etc..


Sodium tungstate is colorless crystal or white crystalline powder. Will weathering in dry air, and lose crystal water at 100 ℃. Sodium tungstate soluble in water, insoluble in ethanol, the relative density of 3.23 ~ 3.25, melting point of 698 ℃ (dry goods). Typically sodium tungstate is dihydrate Na2WO4·2H2O and which is the main raw material in tungsten chemical research, when it crystalline at less than 6 ℃, can obtain decahydrate Na2WO4·10H2O.

Calcium tungstate is a white powder, tetragonal structure, the relative density of 6.062, slightly soluble in water and ammonium chloride solution.

Ammonium tungstate is colorless rhombic crystals, white crystals, soluble in water, insoluble in alcohol. Ammonium tungstate will lost four molecules of water of crystallization at 100 ℃. Ammonium tungstate is usually prepared by the hydrated tungsten acid dissolved in liquid ammonia, can not be prepared directly from the aqueous solution.

Cobalt tungstate with wolframite structure. In CoO-WO3 system is blue-green monoclinic crystals. The relative density of 8.42, slightly soluble in cold dilute acid, dissolved in hot concentrated acid, insoluble in water.

Cadmium tungstate is white or yellow fluorescent crystals, with wolframite structure.

Zinc tungstate is white powder, stable in normal temperature and pressure.