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CAS No.: 7782-50-5
Registry name: Chlorine
Chemical name: Chlorine
Synonyms, Trade names: Chlorum
Chemical name (German): Chlor
Chemical name (French): Chlore
Appearance: greenish-yellow gas with pungent irritating odour
BASIC CHEMICAL AND PHYSICAL DATA
|Rel. molecular mass:||70.91 g|
|Density:||0.567 g/cm3 (liquid, critical density at 144 °C); 3.21 g/l (gas) at 0°C, 1013 hPa|
|Relative gas density:||2.49|
|Vapour pressure:||6.8 bar at 20°C|
|Odour threshold:||0.05 ppm|
|Solvolysis/solubility:||in water: 7.3 g/l at 20°C|
|in tetrachloromethane: 176.5 g/l at 19°C|
|Conversion factors:||1 mg/m3 = 0.339 ml/m3|
|1 ml/m3 = 2.947 mg/m3|
ORIGIN AND USE
Chlorine is used for numerous applications in the chemical industry, for example in the manufacture of chlorinated organic products (synthetics, solvents, insecticides, herbicides). It is also used in the cellulose/paper industry and in laundries as a bleaching agent. Drinking-water and swimming-pool water disinfection is a further application.
In nature, chlorine is chiefly found as chloride (bonded to sodium, potassium and magnesium). A further important chlorine compound is hydrogen chloride. Nowadays, chlorine is primarily produced by electrolysis of alkali-metal chlorides (mercury method and diaphragm method). Use is also still made of chemical methods (SHELL chlorine method, KEL chlorine process, SOUTHWEST POTASH method).
Production figures (worldwide):
1975 = 22.5 million tons; 1983 = 30 million tons; 1994 = >40 million tons
|Humans:||LCLo 837 ppm/30 min, inhalation||acc. UBA, 1986|
|2.5 mg/l air = immediately lethal||acc. TAB. CHEMIE, 1980|
|Rat||LC50 293 ppm/1 h, inhalation||acc. UBA, 1986|
|Mouse||LC50 137 ppm/1 h, inhalation||acc. UBA, 1986|
|Guinea pig||LCLo 330 ppm/7 h, inhalation||acc. UBA, 1986|
|Dog||LCLo 800 ppm/30 min, inhalation||acc. UBA, 1986|
|Trout||0.08 ppm/ 168 h/ freshwater; TLm||acc. UBA, 1986|
|Fish||more than 0.05 mg/l lethal|
Humans/mammals: Chlorine is an extremely caustic, poisonous gas. Symptoms of poisoning following inhalation are the irritation of the mucous membranes of the respiratory tract combined with breathing difficulties, coughing up of blood and low pulse rate. Humans become accustomed to odour and irritation if exposed for a long time or repeatedly. Symptoms may be delayed. Liquid chlorine is extremely caustic on the skin.
Plants: Any description of the damage to plants generally relates to the chloride impact although chlorine gas is also absorbed by plant leaves and destroys plant tissue partly by oxidation and partly by expulsion of hydrogen in organic compounds.
Water hazard class 2. Destroys all aquatic life; kills bacteria as long as free chlorine can be detected. Chlorine reacts with water forming hydrogen chloride/hydrochloric acid depending on water content. Chlorine corrodes several materials when wet.
On expansion, chlorine gas (compressed gas) forms a cold mist which is denser than air; poisonous, corrosive mixtures form in air over the surface of water.
Chlorine is only found in soil in ionised form of its salts (chlorides).
|0.1 mg/m3||IW 1||1)||acc. TA Luft, 1986|
|0.3 mg/m3||IW 2||2)||acc. TA Luft, 1986|
|0.10 mg/m3||Monthly average, plants||acc. LAU-BW|
|Emiss.||D||L||5 mg/m3||mass flow > 50 g/h||acc. TA Luft, 1986|
|1.5 mg/m3||MAK||Peak limit I||DFG, 1989|
|1.5 mg/m3||BAT||acc. LAU-BW|
|1 mg/m3||acc. LAB. CHEMIE, 1980|
|1 mg/m3||acc. SORBE, 1988|
|3 mg/m3||TWA||acc. SORBE, 1988|
|9 mg/m3||STEL||acc. SORBE, 1988|
1) Annual arithmetic mean
2) 98 % of annual 30-minute average
Chlorine is a hazard to all types of water and in particular to drinking water because of its high toxicity and corrosiveness as well as its oxidising effect. Disaster alarm must be given if large quantities of the gas are liberated.
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