Magnesium oxide

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Magnesium oxide
Magnesium oxide.jpg
NaCl polyhedra.png
Identifiers
CAS number1309-48-4 YesY
PubChem14792
ChEMBLCHEMBL1200572 N
RTECS numberOM3850000
ATC code[[ATC code {A02|{A02]]AA02,A06AD02, A12CC10
Properties
Molecular formulaMgO
Molar mass40.3044 g/mol
AppearanceWhite powder
OdorOdorless
Density3.58 g/cm³
Melting point2,852 °C; 5,166 °F; 3,125 K
Boiling point3,600 °C; 6,510 °F; 3,870 K
Solubility in water0.0086 g/100 mL (30 °C)
SolubilitySoluble in acid, ammonia
insoluble in alcohol
Acidity (pKa)10.3
Band gap7.8 eV[1]
Thermal conductivity45–60 W·m−1·K−1[2]
Refractive index (nD)1.736
Structure
Crystal structureHalite (cubic), cF8
Space groupFm3m, No. 225
Coordination
geometry
Octahedral (Mg2+); octahedral (O2–)
Thermochemistry
Std molar
entropy
So298
27 J·mol−1·K−1[3]
Std enthalpy of
formation
ΔfHo298
−602 kJ·mol−1[3]
Hazards
MSDSICSC 0504
EU IndexNot listed
R-phrasesR36, R37, R38
Main hazardsMetal fume fever, Irritant
NFPA 704
Flash pointNon-flammable
Related compounds
Other anionsMagnesium sulfide
Other cationsBeryllium oxide
Calcium oxide
Strontium oxide
Barium oxide
Related compoundsMagnesium hydroxide
Magnesium nitride
 N (verify) (what is: YesY/N?)
Except where noted otherwise, data are given for materials in their standard state (at 25 °C (77 °F), 100 kPa)
Infobox references
 
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Magnesium oxide
Magnesium oxide.jpg
NaCl polyhedra.png
Identifiers
CAS number1309-48-4 YesY
PubChem14792
ChEMBLCHEMBL1200572 N
RTECS numberOM3850000
ATC code[[ATC code {A02|{A02]]AA02,A06AD02, A12CC10
Properties
Molecular formulaMgO
Molar mass40.3044 g/mol
AppearanceWhite powder
OdorOdorless
Density3.58 g/cm³
Melting point2,852 °C; 5,166 °F; 3,125 K
Boiling point3,600 °C; 6,510 °F; 3,870 K
Solubility in water0.0086 g/100 mL (30 °C)
SolubilitySoluble in acid, ammonia
insoluble in alcohol
Acidity (pKa)10.3
Band gap7.8 eV[1]
Thermal conductivity45–60 W·m−1·K−1[2]
Refractive index (nD)1.736
Structure
Crystal structureHalite (cubic), cF8
Space groupFm3m, No. 225
Coordination
geometry
Octahedral (Mg2+); octahedral (O2–)
Thermochemistry
Std molar
entropy
So298
27 J·mol−1·K−1[3]
Std enthalpy of
formation
ΔfHo298
−602 kJ·mol−1[3]
Hazards
MSDSICSC 0504
EU IndexNot listed
R-phrasesR36, R37, R38
Main hazardsMetal fume fever, Irritant
NFPA 704
Flash pointNon-flammable
Related compounds
Other anionsMagnesium sulfide
Other cationsBeryllium oxide
Calcium oxide
Strontium oxide
Barium oxide
Related compoundsMagnesium hydroxide
Magnesium nitride
 N (verify) (what is: YesY/N?)
Except where noted otherwise, data are given for materials in their standard state (at 25 °C (77 °F), 100 kPa)
Infobox references

Magnesium oxide (MgO), 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 separate moisture.

Magnesium oxide was historically known as magnesia alba (literally, the white mineral from Magnesia - other sources give magnesia alba as MgCO3), to differentiate it from magnesia negra, a black mineral containing what is now known as manganese.

While normally "magnesium oxide" means compound MgO, magnesium peroxide MgO2 is also known as a metastable compound. According to evolutionary crystal structure prediction,[4] MgO2 is thermodynamically stable at pressures above 116 GPa, and a totally new semiconducting suboxide Mg3O2 is thermodynamically stable above 500 GPa.

Production[edit]

Magnesium oxide is produced by the calcination of magnesium carbonate or magnesium hydroxide or by the treatment of magnesium chloride with lime followed by heat.

Applications[edit]

A refractory material is one that is physically and chemically stable at high temperatures. "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."[5]

Cement[edit]

MgO is one of the raw materials for making Portland cement in dry process plants. If too much MgO is added, the cement may become expansive.[clarification needed] Production of MgO-based cement using serpentinite and waste Carbon dioxide (CO2) (as opposed to conventional CaO-based cement using fossil fuels) may reduce anthropogenic emissions of CO2.[6]

Desiccant[edit]

MgO is a relatively poor desiccant, but because it neutralizes sulfur oxide acids created by oxidation of Kraft-processed papers, it is used by many libraries for preserving books.[7]

Medical[edit]

In medicine, magnesium oxide is used for relief of 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.[8] In quantities sufficient to obtain a laxative effect, side effects of long-term use include enteroliths resulting in bowel obstruction.[9]

Other[edit]

Unpolished MgO crystal

Precautions[edit]

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.[19]

See also[edit]

References[edit]

  1. ^ Taurian, O.E.; Springborg, M.; Christensen, N.E. (1985). "Self-consistent electronic structures of MgO and SrO". Solid State Communications 55 (4): 351–5. Bibcode:1985SSCom..55..351T. doi:10.1016/0038-1098(85)90622-2. 
  2. ^ Application of magnesium compounds to insulating heat-conductive fillers. konoshima.co.jp
  3. ^ a b Zumdahl, Steven S. (2009). Chemical Principles (6th ed.). Houghton Mifflin Company. p. A22. ISBN 0-618-94690-X. 
  4. ^ Zhu, Qiang; Oganov A.R., Lyakhov A.O. (2013). "Novel stable compounds in the Mg-O system under high pressure.". Phys. Chem. Chem. Phys. 15: 7796–7700. 
  5. ^ Mark A. Shand (2006). The chemistry and technology of magnesia. John Wiley and Sons. ISBN 978-0-471-65603-6. Retrieved 10 September 2011. 
  6. ^ McKenna, Phil (25 September 2010 (updated 1 October 2010)). "Emission control: Turning carbon trash into treasure". New Scientist 2779: 48–51. Retrieved 4 Oct 2010. 
  7. ^ Ferro, Shaunacy (6 January 2012). FYI: Why Do Libraries Have That Smell?. Popular Science. Retrieved 19 Jan 2012. 
  8. ^ Magnesium Oxide. MedlinePlus. Last reviewed 02/01/2009
  9. ^ 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:10.1007/BF00311997. PMID 8680127. 
  10. ^ Tellex, Peter A.; Waldron, Jack R. (1955). "Reflectance of Magnesium Oxide". JOSA 45 (1): 19. doi:10.1364/JOSA.45.000019. 
  11. ^ Tan, C.Y.; Yaghoubi, A.; Ramesh, S.; Adzila, S.; Hassan, M.A.; Kutty, M.G. (2013). "Sintering and mechanical properties of MgO-doped nanocrystalline hydroxyapatite". Ceramics International. doi:10.1016/j.ceramint.2013.04.098. 
  12. ^ Stephens, Robert E. and Malitson, Irving H. (1952). "Index of Refraction of Magnesium Oxide". Journal of Research of the National Bureau of Standards 49 (4): 249–252. doi:10.6028/jres.049.025. 
  13. ^ wipp.energy.gov Step-By-Step Guide for Waste Handling at WIPP. Waste Isolation Pilot Plant. wipp.energy.gov
  14. ^ "Mass Deacidification: Saving the Written Word". Library of Congress. Retrieved 26 September 2011. 
  15. ^ Parkin, S. S. P.; Kaiser, C.; Panchula, A.; Rice, P. M.; Hughes, B.; Samant, M.; Yang, S. H. (2004). "Giant tunnelling magnetoresistance at room temperature with MgO (100) tunnel barriers". Nature Materials 3 (12): 862–867. Bibcode:2004NatMa...3..862P. doi:10.1038/nmat1256. PMID 15516928.  edit
  16. ^ Monsma, D. J.; Parkin, S. S. P. (2000). "Spin polarization of tunneling current from ferromagnet/Al2O3 interfaces using copper-doped aluminum superconducting films". Applied Physics Letters 77 (5): 720. Bibcode:2000ApPhL..77..720M. doi:10.1063/1.127097.  edit
  17. ^ Ikeda, S.; Hayakawa, J.; Ashizawa, Y.; Lee, Y. M.; Miura, K.; Hasegawa, H.; Tsunoda, M.; Matsukura, F.; Ohno, H. (2008). "Tunnel magnetoresistance of 604% at 300 K by suppression of Ta diffusion in CoFeB∕MgO∕CoFeB pseudo-spin-valves annealed at high temperature". Applied Physics Letters 93 (8): 082508. Bibcode:2008ApPhL..93h2508I. doi:10.1063/1.2976435.  edit
  18. ^ Wang, D.; Nordman, C.; Daughton, J. M.; Qian, Z.; Fink, J.; Wang, D.; Nordman, C.; Daughton, J. M.; Qian, Z.; Fink, J. (2004). "70% TMR at Room Temperature for SDT Sandwich Junctions with CoFeB as Free and Reference Layers". IEEE Transactions on Magnetics 40 (4): 2269. doi:10.1109/TMAG.2004.830219.  edit
  19. ^ Magnesium Oxide. National Pollutant Inventory, Government of Australia.

External links[edit]