magnesium oxide
| Dictionary: magnesium oxide |
n.
A white powdery compound, MgO, having a high melting point (2,800°C), used in high-temperature refractories, electrical insulation, food packaging, cosmetics, and pharmaceuticals.
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| Chemistry Dictionary: magnesium oxide |
Variant: magnesia
A white compound, MgO; cubic; r.d. 3.58; m.p. 2800°C. It occurs naturally as the mineral periclase and is prepared commercially by thermally decomposing the mineral magnesite:
MgCO3(s) → MgO(s)+CO2(g)
It has a wide range of uses, including reflective coatings on optical instruments and aircraft windscreens and in semiconductors. Its high melting point makes it useful as a refractory lining in metal and glass furnaces.
| Medical Dictionary: magnesium oxide |
| WordNet: magnesium oxide |
Note: click on a word meaning below to see its connections and related words.
The noun has one meaning:
Meaning #1:
a white solid mineral that occurs naturally as periclase; a source of magnesium
Synonyms: periclase, magnesia
| Wikipedia: Magnesium oxide |
| Magnesium oxide | |
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| IUPAC name |
Magnesium oxide
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| Other names | Magnesia Periclase |
| Identifiers | |
| CAS number | 1309-48-4  |
| PubChem | 14792 |
| RTECS number | OM3850000 |
| ATC code | A02 |
| Properties | |
| Molecular formula | MgO |
| Molar mass | 40.3044 g/mol |
| Appearance | White powder |
| Odor | Odorless |
| Density | 3.58 g/cm3 |
| Melting point |
2852 °C, 3125 K, 5166 °F |
| Boiling point |
3600 °C, 3873 K, 6512 °F |
| Solubility in water | 0.086 g/L[2] |
| Solubility | Soluble in acid, ammonia insoluble in alcohol |
| Band gap | 7.8 eV [1] |
| Refractive index (nD) | 1.736 |
| Structure | |
| Crystal structure | Halite (cubic), cF8 |
| Space group | Fm3m, No. 225 |
| Coordination geometry |
Octahedral (Mg2+); octahedral (O2–) |
| Hazards | |
| MSDS | ICSC 0504 |
| EU Index | Not listed |
| Main hazards | Metal fume fever, irritant |
| NFPA 704 |
 0
1
0
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| 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 |
| (what is this?) (verify) Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa) |
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| Infobox references | |
Magnesium oxide, or magnesia, is a white solid mineral that occurs naturally as periclase and is a source of magnesium (see also oxide). It has an empirical formula of MgO. It is formed by an ionic bond between one magnesium and one oxygen atom. Magnesium oxide is hygroscopic in nature and care must be taken to protect it from moisture. Magnesium hydroxide forms in the presence of water (MgO + H2O → Mg(OH)2), but it can be reversed by heating it to separate moisture.
Contents |
Applications
Desiccant
MgO is an efficient moisture absorbent used by many libraries for preserving books. It is also one of the raw materials for making cement in dry process plants; specifically Portland cement. If too much of MgO is added, the cement may become expansive.
Medical
In medicine, magnesium oxide is used for relief for heartburn and sore stomach, 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.[3] In quantities sufficient to obtain a laxative effect, side effects of long-term use include enteroliths resulting in bowel obstruction.[4]
Other
- MgO is used as an insulator in industrial cables, as a basic refractory material for crucibles and as a principal fireproofing ingredient in construction materials. As a construction material, magnesium oxide wallboards have several attractive characteristics: fire resistance, moisture resistance, mold and mildew resistance, and strength.
- It is used as a reference white color in colorimetry, owing to its good diffusing and reflectivity properties.[5] It may be smoked onto the surface of an opaque material to form an integrating sphere.
- It is used extensively in electrical heating as a component of "CalRod"-styled heating elements. There are several mesh sizes available and most commonly used ones are 40 and 80 mesh per the American Foundry Society. The extensive use is due to its high dielectric strength and average thermal conductivity. MgO is usually crushed and compacted with minimal airgaps or voids. The electrical heating industry also experimented with aluminium oxide, but it is not used anymore.
- Pressed MgO is used as an optical material. It is transparent from 0.3 to 7 µm. The refractive index is 1.72 at 1 µm and the Abbe number is 53.58. It is sometimes known by the Eastman Kodak trademarked name Irtran-5, although this designation is long since obsolete. Crystalline pure MgO is available commercially and has small use in infrared optics.[6]
- It is packed around transuranic waste at the Waste Isolation Pilot Plant, to control the solubility of radionuclides.[7]
Precautions
Magnesium oxide is easily made by burning magnesium ribbon which oxidizes in a bright white light, resulting in a powder. However, the bright flame is very hard to extinguish and it emits a harmful intensity of UV light. Inhalation of magnesium oxide fumes can cause metal fume fever.[8]
Gallery
 Unpolished MgO crystal |
See also
References
- ^ O. E. Taurian et al. (1985). "Self-consistent electronic structures of MgO and SrO". Solid State Communications 55: 351. doi:.
- ^ Material Safety Data Sheet. Magnesium oxide
- ^ MedlinePlus medicinal use
- ^ Tatekawa Y, Nakatani K, Ishii H, et al. (1996). "Small bowel obstruction caused by a medication bezoar: report of a case". Surgery today 26 (1): 68–70. doi:. PMID 8680127.
- ^ Tellex, Peter A.; Waldron, Jack R. (1955). "Reflectance of Magnesium Oxide". JOSA 45 (1): 19. doi:. http://www.opticsinfobase.org/abstract.cfm?URI=josa-45-1-19.
- ^ Index of Refraction of Magnesium Oxide Robert E. Stephens and Irving H. Malitson
- ^ wipp.energy.gov Waste-handling guide for WIPP
- ^ National Pollutant Inventory - Magnesium Oxide Fume Fact Sheet
External links
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 | Dictionary. The American Heritage® Dictionary of the English Language, Fourth Edition Copyright © 2007, 2000 by Houghton Mifflin Company. Updated in 2009. Published by Houghton Mifflin Company. All rights reserved. Read more |
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| Chemistry Dictionary. A Dictionary of Chemistry. Sixth Edition. Copyright © Market House Books Ltd, 2008. All rights reserved. Read more |
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Mentioned in
- magnesia cement
- komatiite (petrology)
- magnesia brick (materials)
- magnesite
- alite
- periclase
- Eschka mixture (analytical chemistry)
- glass sand (materials)
- magnesian limestone (petrology)
- magnesia refractory (materials)
