Chlorine

Chlorine (from the Greek language Chloros, meaning "pale green"), is the chemical element with atomic number 17 and symbol Cl. It is a halogen, found in the periodic table in group 17. As part of common salt and other compounds, it is abundant in nature and necessary to most forms of life, including the human body. As chlorine gas, it is greenish yellow, is two and one half times as heavy as air, has an intensely disagreeable suffocating odor, and is exceedingly poisonous. In its liquid and solid form it is a powerful oxidizing, bleaching, and disinfecting agent.

Occurrence

In nature chlorine is found only as the chloride ion. Chlorides make up much of the salt dissolved in the Earth's oceans—about 1.9% of the mass of seawater is chloride ions. Even higher concentrations of chloride are dissolved in the Dead Sea and in underground brine deposits.

Related Topics:
Chloride ion - Salt - Ocean - Dead Sea - Brine

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Most chlorides are soluble in water, so solid chlorides are usually only found in abundance in dry climates, or deep underground. Common chloride minerals include halite (sodium chloride), sylvite (potassium chloride), and carnallite (potassium magnesium chloride hexahydrate).

Related Topics:
Sodium chloride - Potassium chloride - Carnallite

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Industrially, elemental chlorine is usually produced by the electrolysis of sodium chloride dissolved in water. Along with chlorine, this chloralkali process yields hydrogen gas and sodium hydroxide, according to the chemical equation

Related Topics:
Electrolysis - Chloralkali process - Hydrogen - Sodium hydroxide - Chemical equation

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:2 NaCl + 2 H2O → Cl2 + H2 + 2 NaOH

Related Topics:
NaCl - H₂O - H₂ - NaOH

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