What Is Chlorine?
Chlorine is a halogen element represented by the symbol Cl. It is known for its high reactivity and is a vital chemical element in many applications.
Chlorine is typically encountered as the chlorine molecule (Cl2), which consists of two chlorine atoms bonded together. In nature, chlorine is mostly found as chloride ions in salts, such as sodium chloride (NaCl) and magnesium chloride (MgCl2). There are over 1,500 known chlorine compounds.
Industrially, chlorine is produced by the electrolysis of brine or molten chlorides. The resulting chlorine gas is compressed under high pressure and stored in cylinders or tanks.
Uses of Chlorine
Chlorine is soluble in water and exhibits bleaching and disinfecting properties in aqueous solutions. It is used to disinfect tap water and swimming pools and as a bleaching agent in various industries. Caution is advised as mixing chlorine bleach with acidic detergents can produce toxic chlorine gas.
Chlorine compounds are utilized in the production of plastics, industrial components, and pharmaceuticals, making chlorine an essential ingredient in the chemical industry.
In the human body, chlorine is primarily ingested as sodium chloride and plays a role in the composition of blood and bodily fluids, including as a component of hydrochloric acid in stomach acid, aiding digestion.
Properties of Chlorine
As a highly electronegative element, chlorine tends to form a monovalent anion when ionized. Chlorine gas is a yellow-green, toxic substance with a pungent odor at room temperature. It has a melting point of -149.8 °F (-101 °C) and a boiling point of -29.3 °F (-34.1 °C). Chlorine is chemically active and reacts with a wide range of substances.
The atomic weight of chlorine is 35.45, with an electron configuration of [Ne] 3s2 3p5. Chlorine molecules have a molecular weight of 70.90, a specific gravity of 2.49, and crystallize in an orthorhombic structure.
Other Information on Chlorine
1. Chlorine on Earth
Chlorine is the 18th most abundant element on Earth, existing in various forms such as gaseous, mineral, and ionic. It constitutes 99.6% of the Earth’s mantle, 0.3% of the crust, and 0.1% of seawater.
With Earth’s mass being approximately 6 x 1027 g, there are about 22 x 1024 g of chlorine in the mantle and 60 x 1021 g in the crust. The average concentration of chlorine in seawater is 19.354 g/kg, amounting to roughly 26 x 1021 g in the Earth’s oceans, predominantly in the form of sodium chloride.
Chlorine is also present in river water, lake water, and groundwater, as well as in the cryosphere, troposphere, and stratosphere.
2. Compounds of Chlorine
Chlorides and chlorine compounds contain chlorine as a chloride ion or substituent. A wide variety of organic compounds also contain chlorine, with nearly all elements forming stable compounds with it. However, many chlorine-containing substances are toxic and persist in the environment, leading to regulations due to their potential to produce dioxins during incineration.
3. Isotopes of Chlorine
Chlorine has isotopes ranging from 32 to 40 g/mol, with the two stable isotopes being 35Cl (75.77%) and 37Cl (24.23%). A trace amount of the radioactive isotope 36Cl exists in the environment, produced by cosmic rays and neutron capture. 36Cl, with a half-life of 308,000 years, is useful for radiometric dating and monitoring atmospheric and groundwater changes.