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For water purification.
(Gr. chloros, greenish yellow) Discovered in 1774 by Scheele, who thought it contained
oxygen. Chlorine was named in 1810 by Davy, who insisted it was an element.
In nature it is found in the combined state only, chiefly with sodium as common salt
(NaCl), carnallite, and sylvite.
It is a member of the halogen (salt-forming) group of elements and is obtained from
chlorides by the action of oxidizing agents and more often by electrolysis; it is a
greenish-yellow gas, combining directly with nearly all elements. At 10oC one volume of water
dissolves 3.10 volumes of chlorine, at 30oC only 1.77 volumes.
Chlorine is widely used in making many everyday products. It is used for producing safe
drinking water the world over. Even the smallest water supplies are now usually
It is also extensively used in the production of paper products, dyestuffs, textiles,
petroleum products, medicines, antiseptics, insecticides, food, solvents, paints,
plastics, and many other consumer products.
Most of the chlorine produced is used in the manufacture of chlorinated compounds for
sanitation, pulp bleaching, disinfectants, and textile processing. Further use is in the
manufacture of chlorates, chloroform, carbon tetrachloride, and in the extraction of
Organic chemistry demands much from chlorine, both as an oxidizing agent and in
substitution, since it often brings many desired properties in an organic compound when
substituted for hydrogen, as in one form of synthetic rubber.
Chlorine is a respiratory irritant. The gas irritates the mucus membranes and the
liquid burns the skin. As little as 3.5 ppm can be detected as an odor, and 1000 ppm is
likely to be fatal after a few deep breaths. In fact, chlorine was used as a war gas in
Exposure to chlorine should not exceed 0.5 ppm (8-hour time-weighted average - 40 hour
Sources: CRC Handbook of Chemistry
and Physics and the American Chemical Society.
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