Uses

   The chief use of O₂ is as a fuel (e.g. for oxyacetylene and hydrogen flames), as a supporter of respiration under special conditions (e.g. in air- and spacecraft), and in steel manufacturing.

Fig. 1.1 Uses of sulfur and sulfuric acid (by sulfur content) in the US in 2001. [Data: US Geological Survey.]

   Sulfur, mainly in the form of sulfuric acid, is an enormously important industrial chemical. The amount of sulfuric acid consumed by a given nation is an indicator of that country’s industrial development. Figure 1.1 illustrates applications of sulfur and sulfuric acid.  Sulfur is usually present in the form of an industrial reagent  and it is not necessarily present in the end product.    An important property of Se is its ability to convert light into electricity, and the element is used in photoelectric cells, photographic exposure meters and photocopiers . A major use of selenium is in the glass industry.

   It is used to counteract the green tint caused by iron impurities in soda-lime silica glasses, and is also added to architectural plate glass to reduce solar heat transmission.  In the form of CdS_xSe_1-x, selenium is used as a red pigment in glass and ceramics. Below its melting point, Se is a semiconductor. Tellurium is used as an additive (≈ 0.1%) to low-carbon steels in order to improve the machine qualities of the metal. This accounts for about half of the world’s consumption of tellurium.   

  Catalytic applications are also important, and other applications stem from its semiconducting properties, e.g. cadmium telluride has recently been incorporated into solar cells. However, uses of Te are limited, partly because Te compounds are readily absorbed by the body and excreted in the breath and perspiration as foul-smelling organic derivatives.