CaCl2

Calcium chloride (CaCl2) is an inorganic salt composed of calcium cations Ca2+ and chloride anions Cl−. It is sold commercially as an anhydrous material and as hydrates, including the dihydrate CaCl2·2H2O and the hexahydrate CaCl2·6H2O. The anhydrous form is highly hygroscopic and readily absorbs moisture from air to form hydrates.

CaCl2 is very soluble in water; dissolution is exothermic. In solution, the calcium and chloride ions interact with water, and the solution is typically mildly acidic due to hydrolysis of Ca2+.

In nature, calcium chloride occurs in the mineral antarcticite (CaCl2·6H2O) in some environments. Industrially, it is produced by neutralizing calcium hydroxide with hydrochloric acid (Ca(OH)2 + 2 HCl → CaCl2 + 2 H2O) or by processing calcium-rich brines.

Major uses of CaCl2 include road de-icing and dust control, where its hygroscopic and deliquescent properties help attract moisture and lower the freezing point of water. It is also used as a drying agent for gases and solvents, and in food processing as a firming agent and calcium fortificant (for example in certain canned vegetables and cheeses). In various industrial contexts, it serves as a brine additive and a source of calcium ions.

Safety and environmental considerations: calcium chloride is corrosive to skin and eyes and can cause burns on contact. Inhalation or ingestion can be harmful. Because it is highly soluble, releases into the environment can raise water salinity and impact aquatic life; spills should be contained and cleaned up promptly with appropriate protection.