CaCl

Calcium chloride, usually written CaCl2, is an inorganic salt consisting of calcium cations (Ca2+) and chloride anions (Cl−). It forms colorless or white crystalline solids that are highly hygroscopic, readily absorbing water from the air. The compound exists as the anhydrous salt or as hydrates, with the dihydrate CaCl2·2H2O being common in commerce. The anhydrous form has a high melting point around 772°C, while the dihydrate loses water upon heating and is often favored for ease of handling in industrial use. Note: The standard formula is CaCl2; CaCl without the subscript 2 is not the conventional notation for calcium chloride.

Commercial production typically involves reacting calcium carbonate or calcium hydroxide with hydrochloric acid: CaCO3 + 2 HCl → CaCl2 + CO2 + H2O; Ca(OH)2 + 2 HCl → CaCl2 + 2 H2O. Calcium chloride can also be obtained as a byproduct of certain chemical processes or from brine solutions in chlorine production.

Calcium chloride has a wide range of applications. It is used as a road de-icer and dust suppressant because it lowers the freezing point and absorbs moisture. It serves as a drying agent due to its hygroscopicity and as a calcium fortificant and firming agent in foods. In the food industry, it is used in cheese production and canned vegetables, and sometimes as a yeast nutrient in baking. In construction, it may act as a set-time accelerator for concrete in cold weather. It is also employed in drilling fluids and as a dehydrating agent in various industrial processes.

Safety and handling: calcium chloride solutions are corrosive to skin and eyes and may cause irritation if inhaled as dust. It should be stored in a dry, tightly closed container and handled with appropriate protective equipment. It reacts exothermically with water, requiring careful addition to avoid splashing or vapors.