Tungsten Trioxide (WO3), also known as yellow tungsten oxide, is an oxide of tungsten and an N-type semiconductor as well. These two characteristics make Tungsten Trioxide not only have high density, high boiling point and high melting point, but also have catalytic, optical and electrical properties.
Tungsten Trioxide is a yellow powder, which is insoluble in water, soluble in alkali and slightly soluble in acid. Stable in air, insoluble in water and inorganic acids other than hydrofluoric acid, but slowly soluble in ammonia water and hot concentrated sodium hydroxide solution. The density is 7.2-7.4 g/cm 3, the boiling point is between 1700-2000, the melting point is about 1470, the molecular formula is WO3, and the molecular weight is 231.85.
The properties of Tungsten Trioxide vary with the preparation conditions (speed and temperature): Tungsten Trioxide prepared at low temperature is more active and soluble in water. Tungsten Trioxide prepared at high temperature does not dissolve in water. When Tungsten Trioxide is heated, its color changes from light to dark, and after cooling, it recovers. At 850 degrees, Tungsten Trioxide sublimes significantly, the sublimation heat is 459.8 k/mol, and it is green when melted.
