10 Major Chlorine Applications, Chlorine Sources and Properties

Chlorine role in day to day life

Chlorine Production and Industrial Applications

Chlorine is the most abundant member of the halogen family of periodic table elements. Chlorine is an important chemical in our day-to-day life. Chlorine is a clear amber-colored liquid about 1.5 times heavier than water. Gaseous chlorine is greenish-yellow, about 2.5 times as heavier than air, which will cause it to initially remain near the ground in areas with little air movement. Chlorine has a pungent odor. Chlorine is a powerful oxidizing agent and it must be handled carefully. Chlorine is a yellow-green gas at room temperature.


Chlorine is a major building block for the chemical and pharmaceutical industry. Chlorine is also known as disinfectant in drinking water and in swimming pools, chlorine contributes to advances in areas as diverse as disinfecting, medicine, public safety and enhancing our everyday life.


Chlorine is not flammable, but may react explosively or form explosive compounds with many common substances (including acetylene, ether, turpentine, ammonia, natural gas, hydrogen, and finely divided metals).

Chlorine is slightly water soluble, and reacts with moisture to form hypochlorous acid (HClO) and hydrochloric acid (HCl).

Chlorine is commonly pressurized and cooled for storage and shipment as an amber-colored liquid.

Chlorine gas is a harmful poison, which 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 in the atmosphere causes death in minutes, but less than 0.0001 percent by volume may be tolerated for several hours.


Surprising Sources of Chlorine

  • A Chinese folk medicine plant contains five natural organo chlorine compunds.

  • An Ecuadorian tree frog produces a chlorinated alkaloid, with pain-killing properties several hundred times more powerful than morphine.

  • A natural organ chlorine antibiotic i.e., vancomycin is a key defense

    against hospital Staphylococcus infections.

  • Some natural organ chlorinated products exhibit potent antibacterial and anticancer properties

  • NASA’s Curiosity Rover, currently exploring the surface of Mars, has detected the presence of chlorine on the Red Planet. A Mars expert at the University of Michigan in Ann Arbor, US, stated that "the presence of perchlorates implies a source of chlorine, which was most likely derived from briny water or volcanic activity in the past".

  • NASA also detected chlorinated methane compounds when soil samples were analyzed in Curiosity's on-board laboratory.

  • Chlorine constitutes about 0.01 percent of the Earth's crust.

  • Free chlorine has been reported as a very minor constituent of volcanic gases, of which hydrogen chloride (q.v.) is a fairly common component.

  • 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: chlorine-35 (75.53 percent) and chlorine-37 (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 Properties

Chlorine molecules are composed of two atoms (Cl2). Chlorine combines directly with almost all the elements to give chlorides

Besides the -1 oxidation state of the chlorides, chlorine also exhibits +1, +3, +5, +7 oxidation states, respectively, in the following ions: hypochlorite, ClO-; chlorite, ClO-2 ; chlorate, ClO-3 and perchlorate, ClO-4 .

Chlorine also exists in the forms of four oxides, such as chlorine monoxide (Cl2O), chlorine dioxide (ClO2), dichlorine hexoxide (Cl2O6), and dichlorine heptoxide (Cl2O7). All the four oxides are highly reactive and unstable, have been indirectly synthesized.

Chlorine can displace the heavier halogens, bromine and iodine, from their ionic compounds and undergoes addition or substitution reactions with organic compounds. Chlorine enters directly or as an intermediate into the synthesis of many organic chemicals that are used as solvents, dyes, plastics, and synthetic rubber.

Many chemicals, plastics and medicines depend on chlorine during the manufacturing process, although the chemical is not contained in the end product.

Two third of all chlorine is used in the production of plastics, such as PVC, Poly-Urethanes, Epoxy-resins, Teflon, Neoprene etc., for use in construction, automotive, electronic and electrical industries.

85 per cent of medicines, including many lifesaving drugs, are made using chlorine chemistry.

25 per cent of medical devices contains chlorine, including blood bags, sterile tubing, heart catheters, prosthetics and X-ray films.

More than 90 per cent of Western Europe's drinking water is made safe with the help of chlorine. Worldwide waterborne diseases kill 15 million people each year.


Chlorine Production Methods

Most chlorine is industrially produced by the electrolysis of brine. Chlorine is also obtained as a by-product in the manufacture of sodium metal by the electrolysis of molten sodium chloride.


One of the laboratory methods to prepare chlorine is the reaction between sulfuric acid and sodium hypochlorite or hydrochloric acid with sodium hypochlorite. Sulfuric acid or hydrochloric acid reacts with sodium hypochlorite solution to release chlorine gas but reacts with sodium chlorate to produce chlorine gas and chlorine dioxide gas.


Industrial production of chlorine is through by the following process

  • The membrane cell process
  • The mercury cell process
  • The diaphragm cell process


Chlorine Applications

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, in the separation of such metals as copper, lead, zinc, nickel, and gold from their ores.


Chlorinated solvents are used as an extraction medium in pharmaceutical processes, in printing, mining and plastics processing, in the manufacture of adhesives and in paint & varnish remover


Chlorine compounds have been used in pharmaceutical formulations for many years and play a part in the eradication of infection and disease. It is not only used in antiseptics, but in drugs such as chloramphenicol.



[1] © From, http://www.eurochlor.org/the-chlorine-universe/chlorine-in-nature/chlorine-found-on-mars!.aspx

[2] © From, http://www.c-f-c.com/specgas_products/chlorine.htm

[3] © From, http://www.eurochlor.org/the-chlorine-universe/what-is-chlorine-used-for/chlorine%E2%80%99s-role-in-industrial-processes.aspx

[4] © From, http://www.health.ny.gov/environmental/emergency/chemical_terrorism/chlorine_tech.htm


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