Magnesium is the eighth most abundant element. Magnesium oxide,
MgO, is the second most common compounds in the earth's crust, second only to
silicon dioxide, or ordinary beach sand. In seawater, the
principal magnesium compound is magnesium chloride, MgCl2. The chloride
is obtained directly from seawater and is chiefly used in the
electrolysis process to manufacture magnesium metal. When seawater is not
conveniently available, magesium can be recovered from minerals such as dolomite
(CaCO3.MgCO3) and carnallite (KCl.MgCl2.6H2O).
Discovered in 1775, Magnesium is a chemically active metal. Finely ground
or powdered magnesium burns easily in air, producing a brilliant white light.
Magnesium is an important alloying agent for improving the working characteristics
of aluminum and zinc. It makes them
easier to roll, extrude, weld and machine. Magnesium is also flammable at temperatures
characteristic of burning gasoline and other petrochemicals, so its use as a
structural metal is limited. Insoluble magnesium carbonate and magnesium sulfate,
together with insoluble calcium compounds occur in "hard"
water. These compounds are observed as scales
in pipes and boilers. However, magnesium is an important catalyst
in organic reactions.
Magnesium a metal that is essential to good health. A deficiency in man can
have the same effect as alcoholism. Magnesium hydroxide, Mg(OH)2,
is used in medicine as an antacid.
Other magnesium compounds include:
magnesium chloride, MgCl2, which is used in the preparation of
cotton fabrics.
magnesium bicarbonate, Mg(HCO3)2, which is produced
in solution when water containing carbon dioxide dissolves magnesium carbonate.
It is a cause of hardness in water.
magnesium oxide, MgO, which is used as a refractory lining for metal, glass,
and cement furnaces.
magnesium peroxide, Mg2O2, which is used as a bleach
for dyes and silks.
magnesium sulfate, MgSO4, which is used as a purgative drug and
as an antidote for barium and barbiturate poisoning. It is also used in dyeing
and sizing of textiles, in man-made fibre production, and as a source of magnesium
in fertilizers. One hydrated form, MgSO4.7H2O, is known
as Epsom salt.
