What is "magnesium hydroxide"

magnesium hydroxide \magnesium hydroxide\ n. (Chem.) A slightly alkaline chemical substance, Mg(OH)2, the active principle in the antacid milk of magnesia, also used as a laxative.

n. (context inorganic compound English) The base Mg(OH)₂ that occurs naturally as brucite; it is used as an antacid and in many industrial processes

n. purgative consisting of a milky white liquid suspension of magnesium hydroxide; used as a laxative and (in smaller doses) as an antacid [syn: milk of magnesia]

Magnesium hydroxide is an inorganic compound with the chemical formula of hydrated Mg(OH). It is often known as milk of magnesia, because of its milk-like appearance as a suspension. While magnesium hydroxide has a low solubility in water, with a K of 1.5×10, it is large enough that it will partially dissolve to produce ions in the solution, forming the suspension. A relatively high concentration of magnesium or hydroxide ions would be required to revert the suspension to the solid precipitate by reversing the equilibrium.

In this suspended form, magnesium hydroxide is a common component of antacids and laxatives; it interferes with the absorption of folic acid and iron. The antacid properties come from the hydroxide ions which are responsible for neutralising the acid. The solid mineral form of magnesium hydroxide is known as brucite.