magnesiumchloride

Magnesium chloride is an inorganic salt with the chemical formula MgCl2. It appears as a white to colorless crystalline solid that is highly hygroscopic, meaning it readily absorbs moisture from the air. In solid form it commonly exists as hydrates, especially magnesium chloride hexahydrate (MgCl2·6H2O); the anhydrous salt is also used in some applications. In water, MgCl2 dissociates into Mg2+ and Cl− ions, and in solution the magnesium ion forms various aquated species.

Production of magnesium chloride typically begins with seawater or concentrated brines. The brine is concentrated by evaporation, and magnesium is separated from other ions often by precipitation of Mg(OH)2 using lime (Ca(OH)2). The precipitate is filtered and converted to MgCl2, usually by reaction with hydrochloric acid, yielding a solution that can be dried to produce anhydrous MgCl2 or kept as hydrates for various uses. Alternative routes involve direct acidification of magnesium-containing brines.

Applications of magnesium chloride are diverse. It is widely used as a de-icer and dust suppressant on roads due to its efficacy in lower temperatures and its hygroscopic water-binding properties. It serves as a drying agent for solvents and gases. MgCl2 is a feedstock for the production of metallic magnesium by electrolysis of molten MgCl2 and is also employed as a Lewis acid catalyst in certain organic reactions. In some dietary supplements and medical preparations, magnesium chloride provides a source of magnesium ions.

Safety considerations include its corrosive nature and irritant effects on skin and eyes. It is highly hygroscopic and should be stored in sealed containers to prevent moisture uptake. Proper handling and disposal follow relevant safety and environmental regulations.