| Magnesium oxide | |
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Magnesium oxide |
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Other names
Magnesia |
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| Identifiers | |
| CAS number | 1309-48-4 |
| PubChem | 14792 |
| ChEMBL | CHEMBL1200572 |
| RTECS number | OM3850000 |
| ATC code | A02,A06AD02 |
| 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–) |
| Thermochemistry | |
| Std enthalpy of formation ΔfH |
-601.24 kJ·mol−1 |
| Hazards | |
| MSDS | ICSC 0504 |
| EU Index | Not listed |
| R-phrases | R36, R37, R38 |
| 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 |
| (verify) (what is: /?) 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 (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 bonds. 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), to differentiate it from magnesia negra, a black mineral containing what is now known as manganese.
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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."[3]
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. Production of MgO-based cement using serpentinite and waste CO2 (as opposed to conventional CaO-based cement using fossil fuels) may reduce anthropogenic emissions of CO2.[4]
MgO is relatively poor dessicant, but because it neutralizes sulfur oxide acids created by oxidation of Kraft-processed papers, it is used by many libraries for preserving books.
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.[5] In quantities sufficient to obtain a laxative effect, side effects of long-term use include enteroliths resulting in bowel obstruction.[6]
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.[11]
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