chlorid

Chloride, or chlorid in some languages, refers to the anion Cl− and to many compounds containing this ion. It is the conjugate base of hydrogen chloride (HCl) and forms salts with almost all metals, such as sodium chloride (table salt), potassium chloride, and calcium chloride. In aqueous solution, chloride is colorless and highly soluble. The chloride ion carries a single negative charge and is typically stabilized by hydration in water.

Chloride is the most abundant anion in seawater and in many natural waters, commonly found as part of salts and minerals. Industrially, chloride-containing compounds are produced through mining, evaporation of seawater, or brine processing; chlorine gas is generated by the electrolysis of brine, with the chloride ion serving as the source.

Biological role is significant in animals and humans. Chloride is the major extracellular anion, contributing to osmotic balance, fluid distribution, and acid-base status. It participates in the chloride shift (the exchange of Cl− and bicarbonate across red blood cell membranes) and is a component of gastric hydrochloric acid (HCl) in the stomach. Chloride ions also participate in various transport processes and enzyme activities in cells.

Common uses include seasoning and preserving food (via NaCl), de-icing of roads, water treatment, and the production of chlorine-containing chemicals such as polyvinyl chloride. In medicine, saline solutions provide a source of chloride ions for intravenous therapy. Chloride salts are generally of low toxicity, but hazards arise from excessive intake, concentrated acids, or chlorine gas exposure. Environmental concerns include changes in salinity that affect aquatic ecosystems.