Oxyacids of Selenium and Tellurium

Selenous and tellurous acids can be obtained by the hydrolysis of the tetrahalides, 

In either concentrated solutions or the molten acid, selenite is partially converted by dehydration to pyroselenite, Se205  

Tellurites also form a series of polytellurites (Te4092, Te60132, etc.) that can be obtained as solid salts. 

It is hard to overemphasize the importance of sulfuric acid in chemistry and in the economy. As far as chemicals are concerned, its impact on the economy is second to none. Without sulfuric acid utilization on a large scale, many of the products in general use would not exist, and our very way of life would be altered. The next section presents some of the essential chemistry of H2S04 to show why it so important. 

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