Magnesium sulfate
 hexahydrate
| |
 Anhydrous magnesium sulfate
| |
 Epsomite (heptahydrate)
| |
| Names | |
|---|---|
| IUPAC name
Magnesium sulfate
| |
| Other names
Epsom salt (heptahydrate)
English salt Bitter salts Bath salts | |
| Identifiers | |
| |
3D model (JSmol)
|
|
| ChEBI | |
| ChEMBL | |
| ChemSpider | |
| DrugBank | |
| ECHA InfoCard | 100.028.453 |
PubChem CID
|
|
| RTECS number |
|
| UNII | |
CompTox Dashboard (EPA)
|
|
| |
| |
| Properties | |
| MgSO4 | |
| Molar mass | 120.366 g/mol (anhydrous) 138.38 g/mol (monohydrate) 174.41 g/mol (trihydrate) 210.44 g/mol (pentahydrate) 228.46 g/mol (hexahydrate) 246.47 g/mol (heptahydrate) |
| Appearance | white crystalline solid |
| Odor | odorless |
| Density | 2.66 g/cm3 (anhydrous) 2.445 g/cm3 (monohydrate) 1.68 g/cm3 (heptahydrate) 1.512 g/cm3 (11-hydrate) |
| Melting point | anhydrous decomposes at 1,124°C monohydrate decomposes at 200°C heptahydrate decomposes at 150°C undecahydrate decomposes at 2°C |
| anhydrous 26.9 g/100 mL (0 °C) 35.1 g/100 mL (20 °C) 50.2 g/100 mL (100 °C) heptahydrate 113 g/100 mL (20 °C) | |
| Solubility | 1.16 g/100 mL (18°C, ether) slightly soluble in alcohol, glycerol insoluble in acetone |
| −50·10−6 cm3/mol | |
Refractive index (nD)
|
1.523 (monohydrate) 1.433 (heptahydrate) |
| Structure | |
| monoclinic (hydrate) | |
| Pharmacology | |
| A06AD04 (WHO) A12CC02 (WHO) B05XA05 (WHO) D11AX05 (WHO) V04CC02 (WHO) | |
| Hazards | |
| NFPA 704 (fire diamond) | |
| Safety data sheet (SDS) | External MSDS |
| Related compounds | |
Other cations
|
Beryllium sulfate Calcium sulfate Strontium sulfate Barium sulfate |
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
| |
Magnesium sulfate is an inorganic salt with the formula MgSO4(H2O)x where 0≤x≤7. It is often encountered as the heptahydrate sulfate mineral epsomite (MgSO4·7H2O), commonly called Epsom salt. The overall global annual usage in the mid-1970s of the monohydrate was 2.3 million tons, of which the majority was used in agriculture.[1]
Epsom salt has been traditionally used as a component of bath salts. Epsom salt can also be used as a beauty product. Athletes use it to soothe sore muscles, while gardeners use it to improve crops. It has a variety of other uses: for example, Epsom salt is also effective in the removal of splinters.[2]
Hydrates and anhydrous material, production
A variety of hydrates are known.[3]
The heptahydrate (epsomite) readily loses one equivalent of water to form the hexahydrate. Epsom salt takes its name from a bitter saline spring in Epsom in Surrey, England, where the salt was produced from the springs that arise where the porous chalk of the North Downs meets non-porous London clay.
The monohydrate, MgSO4·H2O is found as the mineral kieserite. It can be prepared by heating the hexahydrate to approximately 150 °C. Further heating to approximately 200 °C gives anhydrous magnesium sulfate. Upon further heating, the anhydrous salt decomposes into magnesium oxide (MgO) and sulfur trioxide (SO3).
The heptahydrate can be prepared by neutralizing sulfuric acid with magnesium carbonate or oxide, but it is usually obtained directly from natural sources.
Uses
Medical
It is on the WHO Model List of Essential Medicines, the most important medications needed in a basic health system.[4]
Magnesium sulfate is a common mineral pharmaceutical preparation of magnesium, commonly known as Epsom salt, used both externally and internally. Magnesium sulfate is highly water-soluble and solubility is inhibited with lipids typically used in lotions. Lotions often employ the use of emulsions or suspensions to include both oil and water-soluble ingredients. Hence, magnesium sulfate in a lotion may not be as freely available to migrate to the skin nor to be absorbed through the skin, hence both studies may properly suggest absorption or lack thereof as a function of the carrier (in a water solution vs. in an oil emulsion/suspension). Temperature and concentration gradients may also be contributing factors to absorption.[5]
Externally, magnesium sulfate paste is used to treat skin inflammations such as small boils or localised infections. Known in the UK as 'drawing paste' it is also used to remove splinters.[6] The standard British Pharmacopoeia composition is dried Magnesium Sulfate 47.76 % w/w, Phenol 0.49 % w/w. and glycerol (E422).[7]
Epsom salt is used as bath salts and for isolation tanks. Magnesium sulfate is the main preparation of intravenous magnesium.
Internal uses include:
- Oral magnesium sulfate is commonly used as a saline laxative or osmotic purgative.
- Replacement therapy for hypomagnesemia[8]
- Magnesium sulfate is a antiarrhythmic agent for torsades de pointes in cardiac arrest under the ECC guidelines and for managing quinidine-induced arrhythmias.[9]
- As a bronchodilator after beta-agonist and anticholinergic agents have been tried, e.g. in severe exacerbations of asthma,[10] magnesium sulfate can be nebulized to reduce the symptoms of acute asthma.[10] It is commonly administered via the intravenous route for the management of severe asthma attacks.
- Magnesium sulfate is effective in decreasing the risk that pre-eclampsia progresses to eclampsia.[11] IV magnesium sulfate is used to prevent and treat seizures of eclampsia. It reduces the systolic blood pressure but doesn't alter the diastolic blood pressure, so the blood perfusion to the fetus isn't compromised. It is also commonly used for eclampsia where compared to diazepam or phenytoin it results in better outcomes.[12][13]
Agriculture
In agriculture, magnesium sulfate is used to increase magnesium or sulfur content in soil. It is most commonly applied to potted plants, or to magnesium-hungry crops, such as potatoes, roses, tomatoes, lemon trees, carrots, and peppers. The advantage of magnesium sulfate over other magnesium soil amendments (such as dolomitic lime) is its high solubility, which also allows the option of foliar feeding. Solutions of magnesium sulfate are also nearly neutral, compared with alkaline salts of magnesium as found in limestone; therefore, the use of magnesium sulfate as a magnesium source for soil does not significantly change the soil pH.[14]
Food preparation
Magnesium sulfate is used as a brewing salt in beer.
It may also be used as a coagulant for making tofu.[15]
Chemistry
Anhydrous magnesium sulfate is commonly used as a desiccant in organic synthesis due to its affinity for water. During work-up, an organic phase is treated with anhydrous magnesium sulfate. The hydrated solid is then removed with filtration or decantation. Other inorganic sulfate salts such as sodium sulfate and calcium sulfate may be used in the same way.
Niche uses
Magnesium sulfate heptahydrate is also used to maintain the magnesium concentration in marine aquaria which contain large amounts of stony corals, as it is slowly depleted in their calcification process. In a magnesium-deficient marine aquarium, calcium and alkalinity concentrations are very difficult to control because not enough magnesium is present to stabilize these ions in the saltwater and prevent their spontaneous precipitation into calcium carbonate.[16]
Minerals
Magnesium sulfates are common minerals in geological environments. Their occurrence is mostly connected with supergene processes. Some of them are also important constituents of evaporitic potassium-magnesium (K-Mg) salts deposits.
Bright spots observed by the Dawn Spacecraft in Occator Crater on the dwarf planet Ceres are most consistent with reflected light from magnesium sulfate hexahydrate.[17]
Almost all known mineralogical forms of MgSO4 are hydrates. Epsomite is the natural analogue of "Epsom salt". Another heptahydrate, the copper-containing mineral alpersite (Mg,Cu)SO4·7H2O,[18] was recently recognized. Both are, however, not the highest known hydrates of MgSO4, due to the recent terrestrial find of meridianiite, MgSO4·11H2O, which is thought to also occur on Mars. Hexahydrite is the next lower (6) hydrate. Three next lower hydrates—pentahydrite, starkeyite, and especially sanderite are rare. Kieserite is a monohydrate and is common among evaporitic deposits. Anhydrous magnesium sulfate was reported from some burning coal dumps.
Double salts
Double salts containing magnesium sulfate exist, for example there are several known sodium magnesium sulfates and potassium magnesium sulfates.
Safety
An abnormally elevated plasma concentration of magnesium is called hypermagnesemia.
References
- ^ Industrial Inorganic Chemistry, Karl Heinz Büchel, Hans-Heinrich Moretto, Dietmar Werner, John Wiley & Sons, 2d edition, 2000, ISBN 978-3-527-61333-5
- ^ "Quick Cures/Quack Cures: Is Epsom Worth Its Salt?". Wall Street Journal. 9 April 2012. Archived from the original on 12 April 2012.
{{cite web}}: Italic or bold markup not allowed in:|publisher=(help); Unknown parameter|deadurl=ignored (|url-status=suggested) (help) - ^ Lucia Odochian "Study of the nature of the crystallization water in some magnesium hydrates by thermal methods," Archived 26 August 2011 at the Wayback Machine Journal of Thermal Analysis and Calorimetry, Volume 45, Number 6, December, 1995. doi:10.1007/BF02547437
- ^ "WHO Model List of Essential Medicines" (PDF). World Health Organization. April 2015. Archived from the original (PDF) on 13 May 2015. Retrieved 14 December 2015.
{{cite web}}: Unknown parameter|deadurl=ignored (|url-status=suggested) (help) - ^ "Does Epsom Salt Work?". www.PainScience.com. Retrieved 5 May 2018.
- ^ [1]
- ^ [2]
- ^ "Pharmaceutical Information – Magnesium Sulfate". RxMed. Archived from the original on 3 April 2009. Retrieved 6 July 2009.
{{cite web}}: Unknown parameter|deadurl=ignored (|url-status=suggested) (help) - ^ "CPR and First Aid: Antiarrhythmic Drugs During and Immediately After Cardiac Arrest (section)". American Heart Association. Retrieved 29 August 2016.
Previous ACLS guidelines addressed the use of magnesium in cardiac arrest with polymorphic ventricular tachycardia (ie, torsades de pointes) or suspected hypomagnesemia, and this has not been reevaluated in the 2015 Guidelines Update. These previous guidelines recommended defibrillation for termination of polymorphic VT (ie, torsades de pointes), followed by consideration of intravenous magnesium sulfate when secondary to a long QT interval.
- ^ a b Blitz M, Blitz S, Hughes R, Diner B, Beasley R, Knopp J, Rowe BH. Aerosolized magnesium sulfate for acute asthma: a systematic review. Chest 2005;128:337-44. doi:10.1378/chest.128.1.337 PMID 16002955.
- ^ Duley, L; Gülmezoglu, AM; Henderson-Smart, DJ; Chou, D (10 November 2010). "Magnesium sulphate and other anticonvulsants for women with pre-eclampsia". The Cochrane Database of Systematic Reviews (11): CD000025. doi:10.1002/14651858.CD000025.pub2. PMID 21069663.
- ^ Duley, L; Henderson-Smart, DJ; Walker, GJ; Chou, D (8 December 2010). "Magnesium sulphate versus diazepam for eclampsia". The Cochrane Database of Systematic Reviews (12): CD000127. doi:10.1002/14651858.CD000127.pub2. PMID 21154341.
- ^ Duley, L; Henderson-Smart, DJ; Chou, D (6 October 2010). "Magnesium sulphate versus phenytoin for eclampsia". The Cochrane Database of Systematic Reviews (10): CD000128. doi:10.1002/14651858.CD000128.pub2. PMID 20927719.
- ^ "Pubchem: magnesium sulfate". Archived from the original on 18 October 2016.
{{cite web}}: Unknown parameter|deadurl=ignored (|url-status=suggested) (help) - ^ Process for producing packed tofu, 28 March 2000
{{citation}}: Unknown parameter|country-code=ignored (help); Unknown parameter|description=ignored (help); Unknown parameter|inventor-first=ignored (help); Unknown parameter|inventor-last=ignored (help); Unknown parameter|inventor2-first=ignored (help); Unknown parameter|inventor2-last=ignored (help); Unknown parameter|inventor3-first=ignored (help); Unknown parameter|inventor3-last=ignored (help); Unknown parameter|inventor4-first=ignored (help); Unknown parameter|inventor4-last=ignored (help); Unknown parameter|patent-number=ignored (help) - ^ "Do-It-Yourself Magnesium Supplements for the Reef Aquarium". Reefkeeping. 2006. Archived from the original on 22 March 2008. Retrieved 14 March 2008.
{{cite web}}: Unknown parameter|deadurl=ignored (|url-status=suggested) (help) - ^ M. C. De Sanctis; E. Ammannito; A. Raponi; S. Marchi; T. B. McCord; H. Y. McSween; F. Capaccioni; M. T. Capria; F. G. Carrozzo; M. Ciarniello; A. Longobardo; F. Tosi; S. Fonte; M. Formisano; A. Frigeri; M. Giardino; G. Magni; E. Palomba; D. Turrini; F. Zambon; J.-P. Combe; W. Feldman; R. Jaumann; L. A. McFadden; C. M. Pieters (2015). "Ammoniated phyllosilicates with a likely outer Solar System origin on (1) Ceres". Nature. 528: 241–244. doi:10.1038/nature16172. PMID 26659184.
- ^ Peterson, Ronald C.; Hammarstrom, Jane M.; Seal, II, Robert R (February 2006). "Alpersite (Mg,Cu)SO4·7H2O, a new mineral of the melanterite group, and cuprian pentahydrite: Their occurrence within mine waste". American Mineralogist. 91 (2–3): 261–269. doi:10.2138/am.2006.1911.