Tellurium trioxide

Tellurium ( VI) oxide

Whitish to yellow- orange solid

Fixed

5.07 g · cm -3

From 400 ° C decomposes to TeO2 and oxygen

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Tellurium is a chemical compound and the anhydride of orthotelluric H6TeO6.

Properties

It is a yellow, trigonal / rhombohedral crystallizing solid and exists in two modifications, the X-ray amorphous yellow-orange α -form and the gray microcrystalline β - form.

Production and representation

The yellow- orange form results in the dehydration of orthotelluric at about 300-320 ° C. The yellow color comes through electron transfer of oxygen into existence on the tellurium ( " charge-transfer "). The gray - β form is produced from the orthotelluric in a sealed tube at 320 ° C in the presence of conc. Sulfuric acid. The β - form is much less reactive. This is evident, for example, the fact that it is insoluble in water, acids and even in hot alkalis. Both forms of Tellurtrioxids decompose above about 400 ° C in tellurium (IV ) oxide and oxygen.