Tungsten Trioxide

Title: Tungsten Trioxide
CAS Registry Number: 1314-35-8
CAS Name: Tungsten oxide (WO3)
Additional Names: tungstic anhydride
Molecular Formula: O3W
Molecular Weight: 231.84
Percent Composition: O 20.70%, W 79.30%
Line Formula: WO3
Literature References: Prepn from sodium tungstate: Hein, Herzog, in Handbook of Preparative Inorganic Chemistry vol. 2, G. Brauer, Ed. (Academic Press, New York, 2nd ed., 1965) pp 1423-1424. Review of toxicology and human exposure: Toxicological Profile for Tungsten (PB2006-100007, 2005) 203 pp.
Properties: Canary yellow, heavy powder; dark orange when heated, regaining the original color on cooling. Insol in water. Sol in caustic alkalies; very slightly sol in acids.
Use: Manuf tungstates which are used for x-ray screens and for fireproofing fabrics.
Tungstic(VI) Acid Tunicamycin Tunichrome B-1 Turanose Turicine

Tungsten trioxide
Sample of Tungsten(VI) Oxide
Kristallstruktur Wolfram(VI)-oxid.png
CAS number 1314-35-8 YesY
PubChem 14811
RTECS number YO7760000
Jmol-3D images Image 1
Molecular formula WO3
Molar mass 231.84 g/mol
Appearance Canary yellow powder
Density 7.16 g/cm3
Melting point 1,473 °C; 2,683 °F; 1,746 K
Boiling point 1,700 °C; 3,090 °F; 1,970 K (approx)
Solubility in water insoluble
Solubility slightly soluble in HF
Crystal structure Monoclinic, mP32, Space group P121/c1, No 14
Octahedral (WVI)
Trigonal planar (O2– )
MSDS External MSDS
EU Index Not listed
Main hazards Irritant
Flash point Non-flammable
Related compounds
Other anions Tungsten trisulfide
Other cations Chromium trioxide
Molybdenum trioxide
Related tungsten oxides Tungsten(III) oxide
Tungsten(IV) oxide
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Except where noted otherwise, data are given for materials in their standard state (at 25 °C (77 °F), 100 kPa)
Infobox references

Tungsten(VI) oxide, also known as tungsten trioxide or tungstic anhydride, WO3, is a chemical compound containing oxygen and the transition metal tungsten. It is obtained as an intermediate in the recovery of tungsten from its minerals.[1] Tungsten ores are treated with alkalis to produce WO3. Further reaction with carbon or hydrogen gas reduces tungsten trioxide to the pure metal.

2 WO3 + 3 C → 2 W + 3 CO2 (high temperature)
WO3 + 3 H2 → W + 3 H2O (550 - 850 °C)

Tungsten(VI) oxide occurs naturally in form of hydrates, which include minerals: tungstite WO3·H2O, meymacite WO3·2H2O and hydrotungstite (of same composition as meymacite, however sometimes written as H2WO4). These minerals are rare to very rare secondary tungsten minerals.