Tungsten trioxide

Tungsten trioxide

Lemon- yellow powder

Fixed

7.16 g · cm -3

1473 ° C

• Insoluble in water and acids
• Soluble in alkaline solutions under tungstate formation

Attention

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Tungsten ( VI) oxide, and tungsten trioxide ( WO3 ), is the most important of the tungsten oxide dar.

Occurrence

Tungsten ( VI) oxide occurs naturally in the form of minerals Elsmoreit ( tungsten ( VI) oxide hemihydrate ) Tungstit ( tungsten ( VI) oxide hydrate) and Meymacit ( tungsten ( VI) oxide dihydrate) before.

Production

The extraction of tungsten trioxide is carried out by annealing of tungsten or tungsten compounds of air.

It can also be represented by the reaction of sodium tungstate dihydrate with hydrochloric acid.

Properties

Tungsten ( VI) oxide is an intensely yellow colored at room temperature, an orange crystal powder upon heating. The crystal lattice of the orthorhombic WO3 consists of WO6 octahedra, which are connected in the three spatial directions via common corners together. Tungsten trioxide is completely insoluble in water and acids, but it can react with water to tungstic acid. With alkalis it reacts to form tungstates.

Use

Tungsten trioxide is used in the ceramics industry as a contact as well as a yellow pigment. A certain importance WO3 could obtain during the production of ultrathin oxide films, which can be coated optical lenses scratch resistant. Also electrochromic glazings containing tungsten trioxide.