Interesting facts about Chlorine

Interesting facts about Chlorine

Chlorine is a toxic, corrosive, greenish yellow gas that is irritating to the eyes and respiratory system; it is two and a half times heavier than air. It becomes a liquid at 34 C 29 F. First prepared from hydrochloric acid and manganese dioxide in 1774 by Carl Wilhelm Scheele, it was considered a compound until Sir Humphry Davy showed 1810 that it cannot be decomposed and that muriatic hydrochloric acid consists of hydrogen and another true element that he named chlorine.

Chlorine constitutes about 0.013 percent of the Earths crust. Chlorine, as the chloride ion Cl, is the main negative ion in ocean water 1.9 percent by weight and in inland seas such as the Caspian Sea, the Dead Sea, and the Great Salt Lake of Utah; it is found in evaporite minerals, for example, combined with sodium, as rock salt halite and in the minerals chlorapatite and sodalite. Natural chlorine is a mixture of two stable isotopes: chlorine35 75.53 percent and chlorine37 24.47 percent. The Chloride ion is present in the body fluids of higher animals and as hydrochloric acid in the digestive secretions of the stomach.

Chlorine gas, a poison, was the first gas used in chemical warfare in World War I. It causes suffocation, constriction of the chest, tightness in the throat, and edema of the lungs. As little as 2.5 mg per litre approximately 0.085 percent by volume in the atmosphere causes death in minutes, but less than 0.0001 percent by volume may be tolerated for several hours. Its strong odour gives warning of its presence at much lower concentrations than are dangerous.

Most chlorine is industrially produced by the electrolysis of brine; some is also obtained as a byproduct in the manufacture of sodium metal by the electrolysis of molten sodium chloride. Chlorine and its compounds are used extensively for bleaching in the paper and textile industries, for disinfecting municipal water supplies, for household bleaches and germicides, and for the production of many organic and inorganic chemicals.