Kloriidioon

Kloriidioon, known in English as the chloride ion, is the monoatomic anion with the chemical formula Cl−. It forms when chlorine gains one electron. It carries a -1 charge and is a major component of many salts, such as sodium chloride (NaCl) and potassium chloride (KCl). In aqueous solution, chloride ions are colorless, highly soluble, and typically surrounded by hydration shells.

Properties: The chloride ion is the conjugate base of hydrochloric acid and is a stable, weakly reactive anion under ordinary conditions. In redox chemistry, Cl− can be oxidized to chlorine gas (Cl2), a reaction with a standard potential of +1.36 V for the Cl2/Cl− couple. It is the most common inorganic anion in seawater, contributing to salinity and osmotic balance.

Occurrence and production: Chloride is abundant in nature, especially in seawater and mineral brines. Industrially, chloride ions are generated and maintained in brine for chemical production; the chloralkali process uses electrolysis of NaCl solution to produce chlorine gas at the anode and NaOH at the cathode, leaving chloride in solution alongside sodium ions.

Biological role: Chloride is an essential electrolyte in many organisms. It helps regulate osmotic pressure and electrical neutrality across cell membranes. In humans, chloride participates in digestion as part of gastric HCl and contributes to acid–base balance; chloride channels and transporters play key roles in cellular homeostasis.

Applications and safety: Chloride ions are ubiquitous in chemistry and industry, chiefly as components of table salt and other alkali salts. They are generally of low toxicity, but extremely concentrated chloride solutions can be corrosive or cause electrolyte imbalances if misused.