Magnesiumhydroxide

Magnesium hydroxide, chemical formula Mg(OH)2, is an inorganic compound that occurs in nature as the mineral brucite. It is a white, odorless solid with very low solubility in water. In aqueous solution it behaves as a weak base, producing a basic pH, but only a small amount dissolves.

Preparation and properties: Magnesium hydroxide is typically prepared by precipitation from soluble magnesium salts with hydroxide bases, according to Mg2+ + 2 OH− → Mg(OH)2(s). It can also be formed by hydrating magnesium oxide: MgO + H2O → Mg(OH)2. Upon heating, it dehydrates around 350 °C to give magnesium oxide: Mg(OH)2 → MgO + H2O. Its low solubility means it is often used in solid form or as a suspension in various applications.

Applications: In medicine, magnesium hydroxide is used as an antacid and as an osmotic laxative (commonly sold as milk of magnesia) to relieve indigestion and constipation. Industrially, it serves as a flame retardant filler for plastics and rubber, a neutralizing agent in wastewater treatment, and a soil conditioner in some agricultural settings. It can also be employed to precipitate certain metals and phosphates in treatment processes.

Safety and handling: Magnesium hydroxide is of relatively low toxicity, but ingestion in large amounts can cause diarrhea and electrolyte imbalances. Inhalation of dust may irritate the airways. Because it is sparingly soluble, systemic magnesium absorption is limited under normal conditions, though caution is advised for individuals with kidney dysfunction or when large quantities are used.