Magnesium oxide

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Magnesium oxide
Magnesium oxide.jpg
IUPAC name
Magnesium oxide
Other names
3D model (JSmol)
ECHA InfoCard 100.013.793 OOjs UI icon edit-ltr-progressive.svg
EC Number
  • 215-171-9
E number E530 (acidity regulators, ...)
PubChem CID
RTECS number
  • OM3850000
  • InChI=1S/Mg.O
  • O=[Mg]
Molar mass 40.304 g/mol [1]
AppearanceWhite powder
Odor Odorless
Density 3.6 g/cm3 [1]
Melting point 2,852 °C (5,166 °F; 3,125 K) [1]
Boiling point 3,600 °C (6,510 °F; 3,870 K) [1]
Solubility Soluble in acid, ammonia
insoluble in alcohol
Electrical resistivity Dielectric [lower-alpha 1]
Band gap 7.8 eV [5]
−10.2·10−6 cm3/mol [6]
Thermal conductivity 45–60 W·m−1·K−1 [7]
6.2 ± 0.6 D
Halite (cubic), cF8
Fm3m, No. 225
a = 4.212Å
Octahedral (Mg2+); octahedral (O2−)
37.2 J/mol K [8]
Std molar
26.95 ± 0.15 J·mol−1·K−1 [9]
−601.6 ± 0.3 kJ·mol−1 [9]
-569.3 kJ/mol [8]
A02AA02 ( WHO ) A06AD02 ( WHO ), A12CC10 ( WHO )
Occupational safety and health (OHS/OSH):
Main hazards
Metal fume fever, Irritant
GHS labelling:
H315, H319, H335
P261, P264, P271, P273, P280, P302+P352, P304+P340, P305+P351+P338, P312, P333+P313, P337+P313, P362, P363, P391, P403+P233, P405
NFPA 704 (fire diamond)
Flash point Non-flammable
NIOSH (US health exposure limits):
PEL (Permissible)
TWA 15 mg/m3 (fume) [10]
REL (Recommended)
None designated [10]
IDLH (Immediate danger)
750 mg/m3 (fume) [10]
Safety data sheet (SDS) ICSC 0504
Related compounds
Other anions
Magnesium sulfide
Other cations
Beryllium oxide
Calcium oxide
Strontium oxide
Barium oxide
Related compounds
Magnesium hydroxide
Magnesium nitride
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Magnesium oxide ( Mg O ), or magnesia, is a white hygroscopic solid mineral that occurs naturally as periclase and is a source of magnesium (see also oxide). It has an empirical formula of MgO and consists of a lattice of Mg2+ ions and O2− ions held together by ionic bonding. Magnesium hydroxide forms in the presence of water (MgO + H2O → Mg(OH)2), but it can be reversed by heating it to remove moisture.

Magnesium oxide was historically known as magnesia alba (literally, the white mineral from Magnesia), to differentiate it from magnesia negra , a black mineral containing what is now known as manganese.

While "magnesium oxide" normally refers to MgO, the compound magnesium peroxide MgO2 is also known. According to evolutionary crystal structure prediction, [11] MgO2 is thermodynamically stable at pressures above 116 GPa (gigapascals), and a semiconducting suboxide Mg3O2 is thermodynamically stable above 500 GPa. Because of its stability, MgO is used as a model system for investigating vibrational properties of crystals. [12]

Electric properties

Pure MgO is not conductive and has a high resistance to electric current at room temperature. The pure powder of MgO has a relative permettivity inbetween 3.2 to 9.9 with an approximate dielectric loss of tan(δ) > 2.16x103 at 1kHz. [2] [3] [4]


Magnesium oxide is produced by the calcination of magnesium carbonate or magnesium hydroxide. The latter is obtained by the treatment of magnesium chloride MgCl
solutions, typically seawater, with limewater or milk of lime. [13]

Mg2+ + Ca(OH)2 → Mg(OH)2 + Ca2+

Calcining at different temperatures produces magnesium oxide of different reactivity. High temperatures 1500 – 2000 °C diminish the available surface area and produces dead-burned (often called dead burnt) magnesia, an unreactive form used as a refractory. Calcining temperatures 1000 – 1500 °C produce hard-burned magnesia, which has limited reactivity and calcining at lower temperature, (700–1000 °C) produces light-burned magnesia, a reactive form, also known as caustic calcined magnesia. Although some decomposition of the carbonate to oxide occurs at temperatures below 700 °C, the resulting materials appears to reabsorb carbon dioxide from the air. [14]


Heating elements

MgO is prized as a refractory material, i.e. a solid that is physically and chemically stable at high temperatures. It has two useful attributes: high thermal conductivity and low electrical conductivity. Filling the spiral Calrod range top heating elements on kitchen electric stoves is a major use. "By far the largest consumer of magnesia worldwide is the refractory industry, which consumed about 56% of the magnesia in the United States in 2004, the remaining 44% being used in agricultural, chemical, construction, environmental, and other industrial applications." MgO is used as a basic refractory material for crucibles. [15]


It is a principal fireproofing ingredient in construction materials. As a construction material, magnesium oxide wallboards have several attractive characteristics: fire resistance, termite resistance, moisture resistance, mold and mildew resistance, and strength. [16] [15]

Gas Mantles

Most gas mantles utilize magnesium oxide. Early iterations such as the Clamond basket used only this. Later versions use ~60% magnesium oxide, with other components such as lanthanum oxide or yttrium oxide making up the rest. Another exception would be thoriated gas mantles.

Niche uses

MgO is one of the components in Portland cement in dry process plants.

Magnesium oxide is used extensively in the soil and groundwater remediation, wastewater treatment, drinking water treatment, air emissions treatment, and waste treatment industries for its acid buffering capacity and related effectiveness in stabilizing dissolved heavy metal species.[ according to whom? ]

Many heavy metals species, such as lead and cadmium are most soluble in water at acidic pH (below 6) as well as high pH (above 11). Solubility of metals affects bioavailability of the species and mobility soil and groundwater systems. Most metal species are toxic to humans at certain concentrations, therefore it is imperative to minimize metal bioavailability and mobility.

Granular MgO is often blended into metals-contaminated soil or waste material, which is also commonly of a low pH (acidic), in order to drive the pH into the 8–10 range where most metals are at their lowest solubilities (basic). Metal-hydroxide complexes have a tendency to precipitate out of aqueous solution in the pH range of 8–10. MgO is widely regarded as the most effective metals stabilization compound when compared to Portland cement, lime, kiln dust products, power generation waste products, and various proprietary products due to MgO's superior buffering capacity, cost effectiveness, and ease/safety of handling.

Most, if not all products that are marketed as metals stabilization technologies create very high pH conditions in aquifers whereas MgO creates an ideal aquifer condition with a pH of 8–10. Additionally, magnesium, an essential element to most biological systems, is provided to soil and groundwater microbial populations during MgO-assisted metals remediation as an added benefit.


Magnesium oxide is used for relief of heartburn and indigestion, as an antacid, magnesium supplement, and as a short-term laxative. It is also used to improve symptoms of indigestion. Side effects of magnesium oxide may include nausea and cramping. [17] In quantities sufficient to obtain a laxative effect, side effects of long-term use include enteroliths resulting in bowel obstruction. [18]


Unpolished MgO crystal MgOcrystal.JPG
Unpolished MgO crystal


Inhalation of magnesium oxide fumes can cause metal fume fever. [32]

See also


  1. At room temperature. [2] [3] [4]

Related Research Articles

<span class="mw-page-title-main">Magnesium</span> Chemical element, symbol Mg and atomic number 12

Magnesium is a chemical element with the symbol Mg and atomic number 12. It is a shiny gray solid which shares many physical and chemical properties with the other five alkaline earth metals.

<span class="mw-page-title-main">Zirconium</span> Chemical element, symbol Zr and atomic number 40

Zirconium is a chemical element with the symbol Zr and atomic number 40. The name zirconium is taken from the name of the mineral zircon, the most important source of zirconium. The word is related to Persian zargun. It is a lustrous, grey-white, strong transition metal that closely resembles hafnium and, to a lesser extent, titanium. Zirconium is mainly used as a refractory and opacifier, although small amounts are used as an alloying agent for its strong resistance to corrosion. Zirconium forms a variety of inorganic and organometallic compounds such as zirconium dioxide and zirconocene dichloride, respectively. Five isotopes occur naturally, four of which are stable. Zirconium compounds have no known biological role.

<span class="mw-page-title-main">Alkaline earth metal</span> Group of chemical elements

The alkaline earth metals are six chemical elements in group 2 of the periodic table. They are beryllium (Be), magnesium (Mg), calcium (Ca), strontium (Sr), barium (Ba), and radium (Ra). The elements have very similar properties: they are all shiny, silvery-white, somewhat reactive metals at standard temperature and pressure.

<span class="mw-page-title-main">Magnesium hydroxide</span> Inorganic compound of formula Mg(OH)2

Magnesium hydroxide is the inorganic compound with the chemical formula Mg(OH)2. It occurs in nature as the mineral brucite. It is a white solid with low solubility in water (Ksp = 5.61×10−12). Magnesium hydroxide is a common component of antacids, such as milk of magnesia.

<span class="mw-page-title-main">Magnesium carbonate</span> Chemical compound

Magnesium carbonate, MgCO3, is an inorganic salt that is a colourless or white solid. Several hydrated and basic forms of magnesium carbonate also exist as minerals.

Neodymium(III) chloride or neodymium trichloride is a chemical compound of neodymium and chlorine with the formula NdCl3. This anhydrous compound is a mauve-colored solid that rapidly absorbs water on exposure to air to form a purple-colored hexahydrate, NdCl3·6H2O. Neodymium(III) chloride is produced from minerals monazite and bastnäsite using a complex multistage extraction process. The chloride has several important applications as an intermediate chemical for production of neodymium metal and neodymium-based lasers and optical fibers. Other applications include a catalyst in organic synthesis and in decomposition of waste water contamination, corrosion protection of aluminium and its alloys, and fluorescent labeling of organic molecules (DNA).

<span class="mw-page-title-main">Aluminium chloride</span> Chemical compound

Aluminium chloride, also known as aluminium trichloride, is an inorganic compound with the formula AlCl3. It forms hexahydrate with the formula [Al(H2O)6]Cl3, containing six water molecules of hydration. Both are colourless crystals, but samples are often contaminated with iron(III) chloride, giving a yellow color.

<span class="mw-page-title-main">Caesium fluoride</span> Chemical compound

Caesium fluoride or cesium fluoride is an inorganic compound with the formula CsF and it is a hygroscopic white salt. Caesium fluoride can be used in organic synthesis as a source of the fluoride anion. Caesium also has the highest electropositivity of all non-radioactive elements and fluorine has the highest electronegativity of all known elements.

<span class="mw-page-title-main">Magnesium nitrate</span> Chemical compound

Magnesium nitrate refers to inorganic compounds with the formula Mg(NO3)2(H2O)x, where x = 6, 2, and 0. All are white solids. The anhydrous material is hygroscopic, quickly forming the hexahydrate upon standing in air. All of the salts are very soluble in both water and ethanol.

<span class="mw-page-title-main">Magnesium silicide</span> Chemical compound

Magnesium silicide, Mg2Si, is an inorganic compound consisting of magnesium and silicon. As-grown Mg2Si usually forms black crystals; they are semiconductors with n-type conductivity and have potential applications in thermoelectric generators.

Sorel cement is a non-hydraulic cement first produced by the French chemist Stanislas Sorel in 1867.

<span class="mw-page-title-main">Aluminium fluoride</span> Chemical compound

Aluminium fluoride refers to inorganic compounds with the formula AlF3·xH2O. They are all colorless solids. Anhydrous AlF3 is used in the production of aluminium metal. Several occur as minerals.

<span class="mw-page-title-main">Gallium(III) oxide</span> Chemical compound

Gallium(III) trioxide is an inorganic compound with the formula Ga2O3. It exists as several polymorphs, all of which are white, water-insoluble solids. Ga2O3 is an intermediate in the purification of gallium, which is consumed almost exclusively as gallium arsenide. The thermal conductivity of β-Ga2O3 is at least one order of magnitude lower than the other wide bandgap semiconductors, such as GaN and SiC. It is further reduced for related nanostructures which are usually used in electronic devices. Heterogeneous integration with high thermal conductivity substrates such as diamond and SiC helps heat dissipation of β-Ga2O3 electronics.

<span class="mw-page-title-main">Thallium(I) chloride</span> Chemical compound

Thallium(I) chloride, also known as thallous chloride, is a chemical compound with the formula TlCl. This colourless salt is an intermediate in the isolation of thallium from its ores. Typically, an acidic solution of thallium(I) sulfate is treated with hydrochloric acid to precipitate insoluble thallium(I) chloride. This solid crystallizes in the caesium chloride motif.

<span class="mw-page-title-main">Thallium(I) iodide</span> Chemical compound

Thallium(I) iodide is a chemical compound with the formula TlI. It is unusual in being one of the few water-insoluble metal iodides, along with AgI, CuI, SnI2, SnI4, PbI2 and HgI2.

<span class="mw-page-title-main">Aluminium diboride</span> Chemical compound

Aluminium diboride (AlB2) is a chemical compound made from the metal aluminium and the metalloid boron. It is one of two compounds of aluminium and boron, the other being AlB12, which are both commonly referred to as aluminium boride.

Barium perchlorate is a powerful oxidizing agent, with the formula Ba(ClO4)2. It is used in the pyrotechnic industry.

<span class="mw-page-title-main">Platinum tetrafluoride</span> Chemical compound

Platinum tetrafluoride is the inorganic compound with the chemical formula PtF
. In the solid state, the compound features platinum(IV) in octahedral coordination geometry.

<span class="mw-page-title-main">Hafnium disulfide</span> Chemical compound

Hafnium disulfide is an inorganic compound of hafnium and sulfur. It is a layered dichalcogenide with the chemical formula is HfS2. A few atomic layers of this material can be exfoliated using the standard Scotch Tape technique (see graphene) and used for the fabrication of a field-effect transistor. High-yield synthesis of HfS2 has also been demonstrated using liquid phase exfoliation, resulting in the production of stable few-layer HfS2 flakes. Hafnium disulfide powder can be produced by reacting hydrogen sulfide and hafnium oxides at 500–1300 °C.

Gallium(I) oxide, digallium monoxide or gallium suboxide is an inorganic compound with the formula Ga2O.


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