Magnesium chloride
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| Names | |
|---|---|
| Other names
Magnesium dichloride
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| Identifiers | |
7786-30-3  7791-18-6 (hexahydrate) 
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| 3D model (Jmol) | Interactive image |
| ChEBI |
CHEBI:6636
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| ChEMBL |
ChEMBL1200547
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| ChemSpider |
22987
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| ECHA InfoCard | 100.029.176 |
| E number | E511 (acidity regulators, ...) |
| 9305 | |
| PubChem | 24584 |
| RTECS number | OM2975000 |
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| Properties | |
| MgCl2 | |
| Molar mass | 95.211 g/mol (anhydrous) 203.31 g/mol (hexahydrate) |
| Appearance | white or colourless crystalline solid |
| Density | 2.32 g/cm3 (anhydrous) 1.569 g/cm3 (hexahydrate) |
| Melting point | 714 °C (1,317 °F; 987 K) 117 °C (243 °F; 390 K) (hexahydrate) on rapid heating: slow heating leads to decomposition from 300 °C (572 °F; 573 K) |
| Boiling point | 1,412 °C (2,574 °F; 1,685 K) |
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anhydrous 52.9 g/100 mL (0 °C) 54.3 g/100 mL (20 °C) 72.6 g/100 mL (100 °C) hexahydrate 167 g/100 mL (20 °C) |
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| Solubility | slightly soluble in acetone, pyridine |
| Solubility in ethanol | 7.4 g/100 mL (30 °C) |
| −47.4·10−6 cm3/mol | |
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Refractive index (nD)
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1.675 (anhydrous) 1.569 (hexahydrate) |
| Structure | |
| CdCl2 | |
| (octahedral, 6-coordinate) | |
| Thermochemistry | |
| 71.09 J/mol K | |
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Std molar
entropy (S |
89.88 J/mol K |
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Std enthalpy of
formation (ΔfH |
-641.1 kJ/mol |
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Gibbs free energy (ΔfG˚)
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-591.6 kJ/mol |
| Pharmacology | |
| A12CC01 (WHO) B05XA11 (WHO) | |
| Hazards | |
| Main hazards | Irritant |
| Safety data sheet | ICSC 0764 |
| R-phrases | R36, R37, R38 |
| S-phrases | S26, S37, S39 |
| NFPA 704 | |
| Flash point | Non-flammable |
| Lethal dose or concentration (LD, LC): | |
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LD50 (median dose)
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2800 mg/kg (oral, rat) |
| Related compounds | |
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Other anions
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Magnesium fluoride Magnesium bromide Magnesium iodide |
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Other cations
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Beryllium chloride Calcium chloride Strontium chloride Barium chloride Radium chloride |
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Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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 (what is ?) |
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| Infobox references | |
Magnesium chloride is the name for the chemical compound with the formula MgCl2 and its various hydrates MgCl2(H2O)x. These salts are typical ionic halides, being highly soluble in water. The hydrated magnesium chloride can be extracted from brine or sea water. In North America, magnesium chloride is produced primarily from Great Salt Lake brine. It is extracted in a similar process from the Dead Sea in the Jordan valley. Magnesium chloride, as the natural mineral bischofite, is also extracted (via solution mining) out of ancient seabeds; for example, the Zechstein seabed in northwest Europe. Some magnesium chloride is made from solar evaporation of seawater. Anhydrous magnesium chloride is the principal precursor to magnesium metal, which is produced on a large scale. Hydrated magnesium chloride is the form most readily available.
MgCl2 crystallizes in the cadmium chloride motif, which features octahedral Mg. A variety of hydrates are known with the formula MgCl2(H2O)x, and each loses water with increasing temperature: x = 12 (−16.4 °C), 8 (−3.4 °C), 6 (116.7 °C), 4 (181 °C), 2 (ca. 300 °C). In the hexahydrate, the Mg2+ remains octahedral, but is coordinated to six water ligands. The thermal dehydration of the hydrates MgCl2(H2O)x (x = 6, 12) does not occur straightforwardly.
As suggested by the existence of some hydrates, anhydrous MgCl2 is a Lewis acid, although a very weak one.
In the Dow process, magnesium chloride is regenerated from magnesium hydroxide using hydrochloric acid:
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