Chlorine
Definition and meaning of Chlorine in chemistry.
Chlorine (Cl2) is a diatomic gas made of two chlorine atoms joined by a single covalent bond, appearing as a dense, yellow-green gas with a sharp, suffocating odor at room temperature. It is a highly reactive nonmetal and one of the strongest common oxidizing agents among the halogens.
In more detail
Industrially, Cl2 is produced by the chlor-alkali process, the electrolysis of concentrated aqueous sodium chloride (brine), which simultaneously yields hydrogen gas and sodium hydroxide. Its strong oxidizing power makes it valuable for disinfecting drinking water and swimming pools, bleaching paper and textiles, and manufacturing PVC plastic and countless organochlorine compounds. Chlorine gas is toxic and corrosive to the respiratory tract even in low concentrations, and it was notoriously deployed as a chemical weapon in World War I.
Key facts
| Formula | Cl2 |
|---|---|
| Field | Inorganic Chemistry |
| Molar mass | 70.90 g/mol |
| Appearance at 25°C | Yellow-green gas, pungent odor |
Chlorine reacts directly with hydrogen gas to form hydrogen chloride: Cl2 + H2 → 2 HCl, a reaction that can proceed explosively when initiated by light or a spark.
Frequently asked questions
Why is chlorine gas dangerous to breathe?
Cl2 is a strong oxidizer that reacts with moisture in the lungs to form hydrochloric and hypochlorous acids, which severely irritate and damage lung tissue even at low concentrations.
How is chlorine gas manufactured?
Most industrial Cl2 comes from the chlor-alkali process, in which electrolysis of aqueous NaCl brine produces chlorine gas at the anode along with hydrogen gas and sodium hydroxide.