Magnesium oxide is often referred to as burnt magnesia or simply magnesium oxide. This substance is a light and fine crystalline white powder. In nature, magnesium oxide is found in the form of a periclase mineral. In the food industry, this substance is known as a food supplement under the code E530.
Magnesium Oxide Properties
The chemical formula of this substance is MgO. This compound is practically odorless, it dissolves well in ammonia and acid, its solubility in water at 30 ° C is only 0.0086 grams / 100 ml, and it does not dissolve at all in alcohol. The molar mass of MgO is 40.3044 g / mol. At 20 ° C, its density is 3.58 g / cm³, boiling point - 3600 ° C, melting point - 2852 ° C. Fine crystalline magnesium oxide is chemically quite active. It is capable of absorbing carbon dioxide to form the corresponding carbonate:
albeit slowly, but still reacts with water, forming an insoluble weak base :
- H 2 O + MgO = Mg (OH) 2 ;
Reacts with acids:
- 2HCl + MgO = MgCl 2 + H 2 O
Calcined magnesium oxide loses its chemical activity. It should also be added that this powder is hygroscopic.
Getting magnesium oxide
In industry, this compound is mainly obtained by calcination. Minerals such as dolomite (MgCO3.CaCO3) or magnesite (MgCO3) are used as raw materials. In addition, burnt magnesia is produced by calcining bischofite (MgCl 2 x 6H 2 O) in water vapor, calcining Mg (OH) 2 and other temperature-unstable Mg compounds. In laboratory conditions, MgO can be obtained by the interaction of its constituent components:
or by thermal decomposition of certain salts or hydroxide:
Depending on the method of producing magnesium oxide, it is customary to distinguish two main types of this compound: light and heavy magnesia. The first is a colorless powder, which quite easily reacts with dilute acids, resulting in the formation of Mg salts. The second consists of large crystals of natural or artificial periclase and is water resistant and more inert.
The use of magnesium oxide
In industry, this compound is used for the manufacture of cements, refractories, as a filler in the manufacture of rubber and for refining petroleum products. Ultralight magnesium oxide is used as a very fine abrasive to clean the surface. In particular, it is used in the electronics industry. In addition, burnt magnesia is widely used in medicine. Here MgO is used in violation of the acidity level of gastric juice, arising from an excess of hydrochloric acid. Magnesium oxide is also taken to neutralize active substances that accidentally enter the stomach. In the food industry, MgO is used as a food additive (code E530), which prevents clumping and caking. Burnt magnesia is also used in gymnastics. Here, athletes apply this powder to their hands in order to make contact with the gymnastic apparatus more reliable. We add also that magnesium oxide is an absolute reflector. The reflection coefficient of this substance in the extended spectral band is unity and therefore it can be used as a white standard.