Sodium Tungstate Introduction

Sodium tungstate, Na2WO4, a tungstate of sodium, is useful as a source of tungsten. It is prepared from tungsten ores used to manufacture tungsten by reducing it. It is often found as the dihydrate, Na2WO4•2H2O. This salt is soluble in water and is a moderately strong oxidizing agent. Like the molybdate, the deep-coloured complex tungstate(VI,V) is formed on reducing the compound with a very mild reducing agent, such as complex organic compounds.

Variants of sodium tungstate:
sodium tungstate or sodium wolframate

Properties: colorless crystal or white crystalline powder. In dry air weathering, lose crystal water at 100 ℃. Soluble in water, soluble in ethanol. The relative density of 3.23 ~ 3.25. Melting point 698 ℃ (dry goods).

Sodium Tungstate

Definition of sodium tungstate:
a tungstate of sodium; esp : the normal salt Na2WO4 that commonly crystallizes with two molecules of water, is usu. obtained during the extraction of tungsten from its ores, and is used chiefly in making other tungsten compounds and in fireproofing textiles

Sodium tungstate, a tungstate of sodium, is useful as a source of tungsten. It is prepared from tungsten ores used to manufacture tungsten by reducing.It is used as catalyst for epoxidation of alkenes and oxidation of alcohols into aldehydes or ketones.It is also used for treatment of diabetes in animal. It is also used in the dye and textile industry,intermediate in preparation of tungsten compounds, fire proofing fabrics & cellulose, alkaloid precipitant.

Use
Used in the manufacture of tungsten, tungstic acid, tungstate, dyes, inks, catalysts.

Reactions of Sodium Tungstate Preparation

Sodium tungstate is the inorganic compound with the formula Na2WO4. This white, water-soluble solid is the sodium salt of tungstic acid. It is useful as a source of tungsten for chemical synthesis. It is an intermediate in the conversion of tungsten ores to the metal.

Treatment of sodium tungstate with hydrochloric acid gives the trioxide:

    Na₂WO₄ + 2 HCl → WO₃ + 2 NaCl + H₂O

This reaction can be reversed using aqueous solution of sodium hydroxide.

Preparation and Structure of Sodium Tungstate

The predominant route to this salt is the extraction of tungsten ores, almost all of which are tungstates. Thus, the ores are treated with a base to give sodium tungstate, as illustrated in the case of wolframite:

Fe/MnWO₄ + 2 NaOH + 2 H₂O → Na₂WO₄•2H₂O + Fe/Mn(OH)₂

Scheelite is treated similarly using sodium carbonate.

Sodium tungstate can also be produced by treating tungsten carbide with a mixture of sodium nitrate and sodium hydroxide in a fusion process which overcomes the high exothermicity of the reaction involved.

Several polymorphs of sodium tungstate are known, three at only one atmosphere pressure. They feature tetrahedral orthotungstate dianions but differ in the packing motif. The WO₄²⁻ anion adopts a structure like sulfate (SO₄²⁻).

Uses of Sodium Tungstate

Uses of Sodium Tungstate：
1、For the mordant, analytical reagents, catalysts, water treatment chemicals, manufacturing fireproof, waterproof material, and phosphorus tungstate, tungsten, boron salts.
2、For the manufacture of tungsten, tungsten acid, tungstate,etc.
3、For the mordant, pigments, dyes, inks.
4、 As a weighting agent for fabric by weavers. This product is used as textile assistants. And a mixture of tungsten acid, ammonium sulfate, ammonium phosphate and other components used in fiber fire and water. This kind of fibers can be made into fireproof rayon and rayon. It can also be used in tanning leather.
5、As anti-corrosion coating for electroplating.
6、As a co-solvent playing a role in reducing firing temperature and complementary color when introducing enamel pigment.
7、For petroleum and aerospace manufacturing industry, aerospace materials.

Sodium Tungstate

Names

IUPAC name   Sodium tungstate

Identifiers

CAS Registry Number   13472-45-2

PubChem       26052

RTECS number     YO7875000

Properties

Chemical formula Na2WO4

Molar mass    293.82 g·mol−1

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

Structure

Crystal structure   rhombic (anhydrous)

orthorhombic (dihydrate)

Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).