Chlorine - Cl
Discovered in 1774 by Carl Wilhelm Scheele, who mistakenly thought it contained oxygen. Chlorine was given its name in 1810 by Humphry Davy, who insisted that it was in fact an element.
This element is a part of the halogen series forming salts. It is extracted from chlorides through oxidation and electrolysis. Chlorine gas is greenish-yellow and combines readily with nearly all other elements.
Chlorine is an important chemical in water purification, in disinfectants, in bleach and in mustard gas.
Chlorine is involved in beaching wood pulp for paper making, bleach is also used industrially to remove ink from recycle paper.
Chlorine often imparts many desired properties in an organic compound when it is substituted for hydrogen (synthetic rubber), so it is widely use in organic chemistry, in the production of chlorates, chloroform, carbon tetrachloride, and in the bromine extraction.
Chlorine in the environment
In nature it is only found combined with other elements chiefly sodium in the form of common salt (NaCl), but also in carnallite, and sylvite. Chlorides make up much of the salt dissolved in the earth's oceans: about 1.9 % of the mass of seawater is chloride ions.
The amount of chloride in soils varies according to the distance from the sea. The average in top soils is about 10 ppm. Plants contain various amount of chlorine; it is an essential microutrient for higher plants where is concentrates in the chloroplasts. Growth suffers if the amount of chloride in the soil fall below 2 ppm, but it rarely happens. The upper limit of tolerance varies according to the crop.
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