Magnesium sulfate

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Magnesium sulfate
Mgaq6SO4 with full charge.png
hexahydrate
Magnesium sulfate anhydrous.jpg
Anhydrous magnesium sulfate
Magnesium sulfate.JPG
Epsomite (heptahydrate)
Names
IUPAC name
Magnesium sulfate
Other names
Epsom salt (heptahydrate)
English salt
Bitter salts
Bath salts
Identifiers
  • 7487-88-9 (anhydrous) ☑Y
  • 14168-73-1 (monohydrate) ☑Y
  • 24378-31-2 (tetrahydrate) ☑Y
  • 15553-21-6 (pentahydrate) ☑Y
  • 13778-97-7 (hexahydrate) ☑Y
  • 10034-99-8 (heptahydrate) ☑Y
3D model (JSmol)
  • Interactive image
ChEBI
  • CHEBI:32599 ☑Y
ChEMBL
  • ChEMBL1200456 ☒N
ChemSpider
  • 22515 ☑Y
DrugBank
  • DB00653 ☑Y
ECHA InfoCard 100.028.453
E number E518 (acidity regulators, ...)
PubChem CID
  • 24083
RTECS number OM4500000
UNII
  • ML30MJ2U7I ☑Y
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
1.523 (monohydrate)
1.433 (heptahydrate)
Structure
monoclinic (hydrate)
Pharmacology
A06AD04 (WHO) A12CC02 (WHO) B05XA05 (WHO) D11AX05 (WHO) V04CC02 (WHO)
Hazards
Safety data sheet External MSDS
NFPA 704
Flammability code 0: Will not burn. E.g., water Health code 1: Exposure would cause irritation but only minor residual injury. E.g., turpentine Reactivity code 0: Normally stable, even under fire exposure conditions, and is not reactive with water. E.g., liquid nitrogen Special hazards (white): no codeNFPA 704 four-colored diamond
0
1
0
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).
☒N verify (what is ☑Y☒N ?)
Infobox references

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:

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

  1. ^ Industrial Inorganic Chemistry, Karl Heinz Büchel, Hans-Heinrich Moretto, Dietmar Werner, John Wiley & Sons, 2d edition, 2000, ISBN 978-3-527-61333-5
  2. ^ "Quick Cures/Quack Cures: Is Epsom Worth Its Salt?". Wall Street Journal. April 9, 2012. Archived from the original on 12 April 2012. 
  3. ^ 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
  4. ^ "WHO Model List of Essential Medicines" (PDF). World Health Organization. April 2015. Archived (PDF) from the original on 13 May 2015. Retrieved 14 December 2015. 
  5. ^ "Does Epsom Salt Work?". www.PainScience.com. Retrieved 2018-05-05. 
  6. ^ [1]
  7. ^ [2]
  8. ^ "Pharmaceutical Information – Magnesium Sulfate". RxMed. Archived from the original on 3 April 2009. Retrieved 6 July 2009. 
  9. ^ "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. 
  10. ^ 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.
  11. ^ Duley, L; Gülmezoglu, AM; Henderson-Smart, DJ; Chou, D (Nov 10, 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. 
  12. ^ Duley, L; Henderson-Smart, DJ; Walker, GJ; Chou, D (Dec 8, 2010). "Magnesium sulphate versus diazepam for eclampsia". The Cochrane Database of Systematic Reviews (12): CD000127. doi:10.1002/14651858.CD000127.pub2. PMID 21154341. 
  13. ^ Duley, L; Henderson-Smart, DJ; Chou, D (Oct 6, 2010). "Magnesium sulphate versus phenytoin for eclampsia". The Cochrane Database of Systematic Reviews (10): CD000128. doi:10.1002/14651858.CD000128.pub2. PMID 20927719. 
  14. ^ "Pubchem: magnesium sulfate". Archived from the original on 18 October 2016. 
  15. ^ US The present invention relates to a novel process for producing packed tofu, particularly a process for producing long-life packed tofu from sterilized soybean milk. 6042851, Matsuura, Masaru; Masaoki Sasaki & Jun Sasakib et al., "Process for producing packed tofu", published 28 Mar 2000 
  16. ^ "Do-It-Yourself Magnesium Supplements for the Reef Aquarium". Reefkeeping. 2006. Archived from the original on 22 March 2008. Retrieved 14 March 2008. 
  17. ^ 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. 
  18. ^ Peterson, Ronald C.; Hammarstrom, Jane M.; Seal, II, Robert R (Feb 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. 

External links

  • International Chemical Safety Cards – Magnesium Sulfate

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