Sodium Tungstate (Sodium Tungsten Oxide) (Na2WO4)-Powder

Characteristic

Sodium tungstate is the inorganic compound with the formula Na₂WO₄. This white, water-soluble solid is the sodium salt of tungstic acid. 

Chemical formula：Na₂WO₄

Molar mass：293.82 g/mol

Appearance：White rhombohedral crystals

Density：4.179 g/cm³ (anhydrous)    3.25 g/cm³ (dihydrate)

Melting point：698 °C (1,288 °F; 971 K)

Solubility in water：57.5 g/100 mL (0 °C)   74.2 g/100 mL (25 °C)   96.9 g/100 mL (100 °C)

Solubility：slightly soluble in ammonia

                    insoluble in alcohol, acid

Crystal structure：Rhombic (anhydrous)

orthorhombic (dihydrate)

Application

The dominant use of sodium tungstate is as an intermediate in the extraction of tungsten from its ores, almost all of which are tungstates. Otherwise sodium tungstate has only niche applications.

In organic chemistry, sodium tungstate is used as catalyst for epoxidation of alkenes and oxidation of alcohols into aldehydes or ketones. It exhibits anti-diabetic effects.

Solutions of sodium polytungstate are used in density separation, since such mixtures are less toxic than bromoform and methylene iodide, but still have densities that fall between a number of naturally coupled minerals.