Tungsten trioxide is yellow powder, insoluble in water, soluble in alkali, slightly soluble in acid, it is used to produce high melting point alloy, tungsten filament and fire proofing material. It can be made by tungsten ore and alkali through melting together with acid.
EINECS Number 215-231-4;
Appearance: Yellow powder；
Solubility: Insoluble in water, soluble in alkali, slightly soluble in acid.
Chemicle property: Significant sublimation at 850 ℃. Almost no reaction with inorganic acid and hydrofluoric acid, can slowly dissolved in ammonia and concentrated alkali solution. React with chlorine into chlorine oxides, but does not react with bromine, iodine.
Structure: it depends on temperature. Under 740 degree celsius, it is tetragonal, 330-740 degree celsius it is orthorhombic, 17-330 degree celsius it is monoclinic, -50-17 degree celsius it is triclinic.