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Magnesium oxide

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Magnesium oxide
Magnesium oxide crystal structure.png
Systematic name Magnesium oxide
Other names Magnesia, Periclase
Molecular formula MgO
SMILES [O-2].[Mg+2]
Molar mass Molar mass::40.3044 g/mol
Appearance white powder
CAS number CAS number::1309-48-4
Density and phase Density::3.58 g/ml, solid
Solubility in water

0.00062 g/100 ml (0°C)
0.0086 g/100 ml (30°C)

Other solvents soluble in acid and ammonia
insoluble in alcohol
Melting point Melting point::2,852°C
Boiling point Boiling point::3,600°C
Basicity (pKb) 10.3
Octahedral (Mg2+); octahedral (O2–)
Crystal structure Halite (cubic)
Dipole moment 6.2± 0.6 D
MSDS Material safety data sheet
Main hazards metal fume fever, irritant
NFPA 704

NFPA 704 svg.png

Flash point non-flammable
Related compounds
Other anions magnesium sulfide
Other cations

beryllium oxide
calcium oxide
strontium oxide
barium oxide

Related compounds

magnesium hydroxide
magnesium nitride

Except where noted otherwise, data are given for
materials in their standard state (at 25 °C, 100 kPa)
Disclaimer and references

Magnesium oxide is an ionic compound that appears as a white, powdery solid. It can also be referred to as magnesia. This compound is perhaps best known for its use as a medication that can treat symptoms such as heartburn or indigestion. It can be formed by burning magnesium ribbon in the air and also occurs naturally as periclase. Magnesium oxide is a relatively safe chemical, but it can be a mild irritant.


A sample of magnesium oxide

Magnesium oxide is a powdery,crystalline solid.[1][2] It is white in color. This compound melts at a relatively high temperature of about 2830 degrees Celsius and boils at 3600 degrees Celsius.[2][3] It has a density of 3.58 g/cubic cm.[4]Magnesium oxide is considered to be a good thermal conductor. It also can typically resist corrosion.[5]

Because magnesium oxide is hygroscopic, it possesses the ability to absorb moisture from the atmosphere, forming magnesium hydroxide.[6] Magnesium oxide consists of a magnesium atom and an oxygen atom joined together by an ionic bond. [5] Due to the strong ionic bonds that hold it together, this compound has a very low solubility of 0.0086 grams per 100 milliliters of water. Like other metal oxides, magnesium oxide is a base, with a high pH of 10.3.[3][7] Magnesium oxide is not a particularly dangerous substance and is noncombustible, although it can irritate the eyes or nose.[7]

Synthesis / Occurrences

Periclase, a form of magnesium oxide

There are many ways that magnesium oxide can be formed. One way in which magnesium oxide is made is the burning of magnesium ribbon in air. This creates a white smoke that contains mostly fine particles of magnesium oxide. It then forms into a white powder consisting of about 90 percent magnesium oxide and 10 percent magnesium nitride, since both the oxygen and the nitrogen in the air will react with the magnesium.[8] One can create magnesium oxide commercially by heating magnesite to a temperature of 600-800 degrees Celsius, eliminating much of the carbon dioxide.[5]

Magnesium oxide can also result from the breaking down of magnesium carbonate or magnesium hydroxide. Both will create magnesium oxide in a reaction that occurs when they are in the presence of heat.[2] Most magnesium oxide is obtained by processing materials like magnesite, a form of magnesium carbonate, and brine, which can contain magnesium chloride.[9] Magnesium oxide can also occur as periclase. Periclase is a mineral that can usually be located in dolomitic limestone.[10]


Magnesium oxide has several different applications. Magnesium oxide's ability to absorb water makes it an ideal substance for preserving books. This property also makes magnesium oxide useful for rock climbers, who apply it to their hands to increase grip.[6] Magnesium oxide is also used in industry and is a component in many different fertilizers and animal feeds. It can also fireproof materials used in construction.

Magnesium oxide can help insulate cables. It is also used for refractory purposes, such as lining crucibles. This compound forms the white coloring that forms the reference in colorimetry.[5]Colorimetry is the study of measuring and forming definitions for different colors based on how most people will perceive them.[11] However, one of magnesium oxide's most important and widely known uses is as a medication.[5]

Medicinal Uses

As a medicine, magnesium oxide can be used as a supplement for people with a deficiency of magnesium.[12] Magnesium is necessary for cells, nerves, muscles, bones, and the heart to work properly.[13] Magnesium oxide also has the ability to cure symptoms such as heartburn, stomach problems, or indigestion. This compound is also used as a laxative prior to surgeries.[14] Some research even suggests that magnesium oxide is helpful in treating migraines.[15]

Magnesium oxide can typically be found as a tablet or capsule. It is normally taken orally one to four times each day.Despite its many benefits, magnesium oxide, like most medications, does have some side effects. These could include cramping and weakness or nausea.[14] Magnesium oxide can produce several allergic reactions, including trouble breathing, hives, and swelling of the lips, tongue, or face.[12]


  1. magnesium oxide The Free Dictionary. Web. Accessed on December 24, 2014. Author unknown.
  2. 2.0 2.1 2.2 Winter, Mark. Magnesium: magnesium oxide WebElements. Web. Accessed on December 24, 2014.
  3. 3.0 3.1 Cotton, Simon. Magnesium oxide Royal Society of Chemistry. Web. Published on August 13, 2014.
  4. Magnesium Oxide Wikidot. Web. Last updated on January 30, 2008. Author unknown.
  5. 5.0 5.1 5.2 5.3 5.4 Magnesium Oxide Overview Magnesium Web. Accessed on December 30, 2014. Author unknown.
  6. 6.0 6.1 Magnesium Oxide Facts eHow. Web. Accessed on December 27, 2014. Author unknown.
  7. 7.0 7.1 Hinkson, N.C. The Physical Properties of Magnesium Oxide Web. Last updated on July 24, 2011.
  8. Ophardt, Charles E. Formation of Ionic Magnesium Compounds Virtual Chembook-Elmhurst College. Web. Accessed on January 2, 2015.
  9. Basic Facts about Magnesium Oxide and Magnesium Hydroxide Martin Marietta Magnesia Specialties. Web. Accessed on January 6, 2015. Author unknown.
  10. Periclase Web. Accessed on January 6, 2015. Author unknown.
  11. Colorimetry Color Web. Accessed on January 24, 2015. Author unknown.
  12. 12.0 12.1 [ magnesium oxide ] Web. Accessed on January 25, 2015. Author unknown.
  13. magnesium oxide WebMD. Web. Accessed on January 25, 2015. Author unknown.
  14. 14.0 14.1 Magnesium Oxide MedlinePlus. Web. Last updated on December 24, 2014. Author unknown
  15. What Is Magnesium Oxide? EverydayHealth. Web. Accessed on January 25, 2015. Author unknown.

See Also