MgCl2

Magnesium chloride, MgCl2, is an inorganic salt that appears as a white crystalline solid and is highly hygroscopic, readily absorbing moisture from the air. It exists in several hydrates, with magnesium chloride hexahydrate (MgCl2·6H2O) being the most common in natural mineral form, known as bischofite. The anhydrous salt is less common in nature but can be produced industrially. In water, MgCl2 dissociates into Mg2+ and Cl− ions, and its solutions are typically mildly acidic due to hydrolysis.

Occurrence and production

MgCl2 occurs naturally as the mineral bischofite, a hydrated form found in salt deposits from evaporated seawater. Commercially, it is produced from seawater or brines by evaporation and purification, often yielding the hydrated salt. The anhydrous form can be obtained by removing water from the hydrates through controlled heating.

Uses

Magnesium chloride has several applications. It is widely used as a de-icing and anti-icing agent for roads and sidewalks, and as a dust suppressant on unpaved surfaces. In food production, it serves as a coagulant for tofu (nigari) and is used as a source of magnesium in dietary supplements and some pharmaceutical preparations. Its hygroscopic nature also makes it useful as a drying agent in certain industrial processes.

Safety and handling

Concentrated MgCl2 solutions and the solid are corrosive to skin and eyes and can be irritating if inhaled. It should be handled with appropriate protective equipment, kept away from moisture-sensitive materials, and stored in a well-ventilated area. Proper care is required to prevent corrosion of metals and equipment.