CAS number : 13472-45-2
Molecular weight :329.86
Molecular formula/chemical symbol :Na2WO4.2H2O
Description :
The predominant route to this salt is the extraction of tungsten ores, almost all of which are tungstates. Thus, the ores, are treated with 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-).
Sodium tungstate |
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Sodium tungstate |
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Identifiers |
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YO7875000 |
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Jmol-3D images |
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Properties |
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Na2O4W |
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293.82 g mol?1 |
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Appearance |
white rhombohedral crystals |
4.179 g/cm3 (anhydrous) |
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698 °C, 971 K, 1288 °F |
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Solubility in water |
57.5 g/100 mL (0 °C) |
Structure |
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rhombic (anhydrous) |
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Y (verify) (what is: Y/N?) |
USES :
For the metal tungsten, tungsten acid and tungstate manufacturing as well as dyes, pigments, inks, such as electroplating.
For fabric and cellulose fire retardant, catalyst, etc.
Keyword:Catalyst;Environmental protection paint
Report :