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Magnesium Oxide & Water

Magnesium hydroxide is formed by mixing magnesium oxide with water. The compound has several industrial uses, and, when suspended in water, has medical applications as an over-the-counter drug.

  1. Magnesium Oxide

    • Magnesium oxide (MgO), also called magnesia, is a compound of the metal magnesium and oxygen. It is the second most common compound in the crust of the earth.

    Forming Magnesium Hydroxide

    • Magnesium oxide combined with water (H2O) forms the inorganic compound magnesium hydroxide [Mg(OH)2]. It is a white powder. As a solid, it is called brucite.

    Industrial Uses of Magnesium Hydroxide

    • Magnesium hydroxide is used in the processing of uranium, pulping wood, treating wastewater and refining sugar. It is also a flame retardant and smoke suppressant effective on plastics, synthetic rubber, some polyesters and urethane foam.

    Suspension of Magnesium Hydroxide

    • Magnesium hydroxide only slightly soluble in water, but it can be suspended in water. A solution is homogeneous mixture of two or more substances, while a suspension is a mixture in which fine particles are suspended in a fluid where they are supported by buoyancy. The particles in a suspension are larger than those in a solution. They can be observed under a microscope or sometimes by the naked eye. The particles in a suspension will sink to the bottom if it is allowed to stand, which is why you need to shake some medicines well before you use them.

    Milk of Magnesia

    • In medicine, a suspension of magnesium hydroxide is used as an antacid and as a laxative. Another name for magnesium hydroxide suspended in water is milk of magnesia. Brand names include Phillips' Milk of Magnesia, Milk of Magnesia, Dulcolax Milk of Magnesia, Ex-Lax Milk of Magnesia. Pain medications may also contain magnesium hydroxide as well as acetaminophen or aspirin. According to the Mayo Clinic, milk of magnesia is a saline type of laxative. Saline (salt) laxatives draw water into the intestine and stimulate the bowel to move. Milk of magnesia is used as an occasional treatment for constipation and should not be used long-term. As an antacid, magnesium hydroxide is used to treat heartburn, which occurs when stomach acid backs up into the esophagus. Milk of magnesia neutralizes stomach acid, according to the Mayo Clinic.

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