Magnesium oxide is often called burnt magnesia or simply magnesium oxide. This substance is a light and fine crystalline white powder. Magnesium oxide occurs naturally as the mineral periclase. In the food industry, this substance is known as a food additive under the code E530.
Properties of magnesium oxide
The chemical formula of this substance is MgO. This compound is practically odorless, it dissolves well in ammonia and acid, in water its solubility at 30 ° C is only 0.0086 grams / 100 ml, and in alcohol it does not dissolve at all. 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 able to absorb carbon dioxide to form the corresponding carbonate:
- MgO + CO2=MgCO3;
although slowly, but still reacts with water, forming an insoluble weak base:
- H2O + MgO=Mg(OH)2;
reacts with acids:
- 2HCl + MgO=MgCl2 + H2O
Calcined magnesium oxide loses its chemical activity. It should also be added that this powder is hygroscopic.
Obtaining magnesium oxide
In industry, this compound is mainly obtained by roasting. Minerals such as dolomite (MgCO3. CaCO3) or magnesite (MgCO3) are used as raw materials. In addition, burnt magnesia is produced by calcining bischofite (MgCl2 x 6H2O) in water vapor, calcining Mg(OH)2 and others temperature-labile Mg compounds. Under laboratory conditions, MgO can be obtained by the interaction of its constituent components:
- 2Mg + O2=2MgO;
or through thermal decomposition of certain s alts or hydroxide:
- MgCO3=MgO + CO2.
Depending on the method of obtaining 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 enters into various reactions with dilute acids, resulting in the formation of Mg s alts. The second consists of large crystals of natural or artificial periclase and is water resistant and more inert.
Application of magnesium oxide
In industry, this compound is used for the manufacture of cements, refractories, as a filler inin the production of rubber and for refining petroleum products. Ultralight magnesium oxide is used as a very fine abrasive, which is used 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 level of acidity of gastric juice that occurs due to excess 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 also add that magnesium oxide is an absolute reflector. The reflection coefficient of this substance in the extended spectral band is equal to unity and therefore it can be used as a standard for white color.
