{{short description|Chemical compound}}
{{Use dmy dates|date=June 2011}}
{{About|the chemical compound|the use of magnesium sulfate as a medication|Magnesium sulfate (medical use)}}
{{chembox
| Verifiedfields = changed
| Watchedfields = changed
| verifiedrevid = 476997098
| Name = Magnesium sulphate
| ImageFile1 = Mgaq6SO4 with full charge.png
| ImageCaption1 = hexahydrate
| ImageFile2 = Magnesium sulfate anhydrous.jpg
| ImageCaption2 = Anhydrous magnesium sulfate
| ImageFile3 = Magnesium sulfate.JPG
| ImageCaption3 = [[Epsomite]] (heptahydrate)
| IUPACName = Magnesium sulfate
| OtherNames = Epsom salt (heptahydrate)<br /> English salt<br />Bitter salts<br />Bath salts
|Section1={{Chembox Identifiers
| UNII_Ref = {{fdacite|correct|FDA}}
| UNII = ML30MJ2U7I
| ChEMBL_Ref = {{ebicite|changed|EBI}}
| ChEMBL = 1200456
| InChI = 1/Mg.H2O4S/c;1-5(2,3)4/h;(H2,1,2,3,4)/q+2;/p-2
| InChIKey = CSNNHWWHGAXBCP-NUQVWONBAQ
| DrugBank_Ref = {{drugbankcite|correct|drugbank}}
| DrugBank = DB00653
| ChEBI_Ref = {{ebicite|correct|EBI}}
| ChEBI = 32599
| SMILES = [Mg+2].[O-]S([O-])(=O)=O
| StdInChI_Ref = {{stdinchicite|correct|chemspider}}
| StdInChI = 1S/Mg.H2O4S/c;1-5(2,3)4/h;(H2,1,2,3,4)/q+2;/p-2
| StdInChIKey_Ref = {{stdinchicite|correct|chemspider}}
| StdInChIKey = CSNNHWWHGAXBCP-UHFFFAOYSA-L
| CASNo = 7487-88-9
| CASNo_Comment = (anhydrous)
| CASNo_Ref = {{cascite|correct|CAS}}
| CASNo1_Ref = {{cascite|correct|??}}
| CASNo1 = 14168-73-1
| CASNo1_Comment = (monohydrate)
| CASNo2_Ref = {{cascite|correct|??}}
| CASNo2 = 24378-31-2
| CASNo2_Comment = (tetrahydrate)
| CASNo3_Ref = {{cascite|correct|??}}
| CASNo3 = 15553-21-6
| CASNo3_Comment = (pentahydrate)
| CASNo4_Ref = {{cascite|correct|??}}
| CASNo4 = 13778-97-7
| CASNo4_Comment = (hexahydrate)
| CASNo5_Ref = {{cascite|correct|??}}
| CASNo5 = 10034-99-8
| CASNo5_Comment = (heptahydrate)
| ChemSpiderID_Ref = {{chemspidercite|correct|chemspider}}
| ChemSpiderID = 22515
| PubChem = 24083
| EINECS =
| RTECS = OM4500000
 }}
|Section2={{Chembox Properties
| Formula = MgSO<sub>4</sub>
| Appearance = white crystalline solid
| Odor = odorless
| Density = 2.66 g/cm<sup>3</sup> (anhydrous)<br /> 2.445 g/cm<sup>3</sup> (monohydrate)<br /> 1.68 g/cm<sup>3</sup> (heptahydrate)<br /> 1.512 g/cm<sup>3</sup> (11-hydrate)
| MolarMass = 120.366 g/mol (anhydrous)<br />138.38 g/mol (monohydrate)<br />174.41 g/mol (trihydrate)<br />210.44 g/mol (pentahydrate)<br />228.46 g/mol (hexahydrate)<br />246.47 g/mol (heptahydrate)
| Solubility = ''anhydrous''<br /> 26.9 g/100 mL (0 °C)<br /> 35.1 g/100 mL (20 °C)<br /> 50.2 g/100 mL (100 °C) <hr /> ''heptahydrate''<br /> 113 g/100 mL (20 °C)
| SolubleOther = 1.16 g/100 mL (18°C, [[diethyl ether|ether]])<br /> slightly soluble in [[ethanol|alcohol]], [[glycerol]]<br /> insoluble in [[acetone]]
| MeltingPt = anhydrous decomposes at&nbsp;1,124°C<br />monohydrate decomposes at&nbsp;200°C<br />heptahydrate decomposes at&nbsp;150°C<br />undecahydrate decomposes at&nbsp;2°C
| RefractIndex = 1.523 (monohydrate)<br /> 1.433 (heptahydrate)
| MagSus = −50·10<sup>−6</sup> cm<sup>3</sup>/mol
 }}
|Section3={{Chembox Structure
| Coordination =
| CrystalStruct = [[monoclinic]] (hydrate)
 }}
|Section6={{Chembox Pharmacology
| ATCCode_prefix = A06
| ATCCode_suffix = AD04
| ATC_Supplemental = {{ATC|A12|CC02}} {{ATC|B05|XA05}} {{ATC|D11|AX05}} {{ATC|V04|CC02}}
}}
|Section7={{Chembox Hazards
| ExternalSDS = [http://hazard.com/msds/mf/baker/baker/files/m0234.htm External MSDS]
| NFPA-H = 1
| NFPA-F = 0
| NFPA-R = 0
 }}
|Section8={{Chembox Related
| OtherCations = [[Beryllium sulfate]]<br />[[Calcium sulfate]]<br />[[Strontium sulfate]]<br />[[Barium sulfate]]
| OtherCompounds =
 }}
}}
'''Magnesium sulfate''' is a [[chemical compound]], a [[salt (chemistry)|salt]] with the formula {{chem|MgSO|4}}, consisting of [[magnesium]] [[cation]]s {{chem|Mg|2+}} (20.19% by mass) and [[sulfate]] [[anion]]s {{chem|SO|4|2-}}. It is a white crystalline solid, soluble in water but not in [[ehanol]].

Magnesium sulfate is usually encountered in the form of a [[water of crystallization|hydrate]] {{chem|MgSO|4|•''n''H|2|O}}, for various values of ''n'' between 1 and 11.   The most common is the heptahydrate {{chem|MgSO|4|·7H|2|O}}, kown as '''Epsom salt''', which is a [[household chemical]] with many traditional uses, including [[bath salts]].<ref name=wsjdXXXX/>

The main use of magnesium sulfate is in agriculture, to correct soils deficients in magnesium (an essential plant nutrient).  The monohydrate is favored for this use; by the mid-1970s, its production was  2.3&nbsp;million tons per year.<ref name=buch2000/>  The [[hydrate|anhydrous]] form and several hydrates occur in nature  [[sulfate mineral|mineral]]s, and the salt is a significant component of the water from some [[spring (water)|springs]].

==Hydrates==
Magnesium sulfate can crystallize as several hydrates, including:
* Anyhdrous, {{chem|MgSO|4}}. Occurs in nature as the mineral [[anhydrite]], with [[orthorhombic]] [[crystal]] structure.
* Monohydrate, {{chem|MgSO|4|•H|2|O}}; [[kieserite]], [[monoclinic]].<ref name=odoc1995/>
* Dihydrate, {{chem|MgSO|4|·2H|2|O}}; [[orthorhombic]].
* Tetrahydrate, {{chem|MgSO|4|•4H|2|O}}; [[monoclinic]].
* Pentahydrate, {{chem|MgSO|4|•5H|2|O}}; [[pentahydrite]], [[triclinic]].<ref name=odoc1995/>
* Hexahydrate, {{chem|MgSO|4|•5H|2|O}}; [[monoclinic]].
* Heptahydrate, {{chem|MgSO|4|•7H|2|O}}  ("Epson salt"); [[epsomite]], [[orthorhombic]].<ref name=odoc1995/>
* Undecahydrate, {{chem|MgSO|4|•7H|2|O}}; [[meridianiite]], [[triclinic]].

All the hydrates lose water upon heating. Above 320 °C only the anhydrous form is stable. It decomposes without melting at 1124°C into [[magnesium oxide]] (MgO) and [[sulfur trioxide]] (SO<sub>3</sub>).

===Heptahydrate (Epsom salt)===

The heptahydrate takes its common name "Epsom salt" 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 heptahydrate readily loses one equivalent of water to form the hexahydrate.

===Monohydrate===

The monohydrate can be prepared by heating the hexahydrate to approximately 150&nbsp;°C.  Further heating to approximately 300-320&nbsp;°C gives anhydrous magnesium sulfate. 

==Natural occurence==
Magnesium sulfates are common minerals in geological environments. Their occurrence is mostly connected with [[supergene (geology)|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 (dwarf planet)|Ceres]] are most consistent with reflected light from magnesium sulfate hexahydrate.<ref name=sanc2015/>

Almost all known mineralogical forms of MgSO<sub>4</sub> are hydrates. [[Epsomite]] is the natural analogue of "Epsom salt". [[Meridianiite]], MgSO<sub>4</sub>·11H<sub>2</sub>O, has been observed on the surface of frozen lakes and 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.

==Preparation==

Magnesium sulfate is usually obtained directly from dry lake beds and other natural sources. It can also be prepared by reacting magnesite ([[magnesium carbonate]], {{chem|MgCO|3}}) or [[pirolusite|magnesia]] ([[magnesium oxide|oxide]], {{chem|MgO}}) with [[sulfuric acid]]. 

Another possible method is to treat seawater or manesium-containing industrial wastes so as to precipitate [[magnesium hydroxide]], and react the precititate with sulfuric acid. 

==Uses==
===Medical===
{{Main|Magnesium sulfate (medical use)}}

Magnesium sulfate is used both externally (as Epsom salt) and internally.  

The main external use is the formulation as [[bath salts]], especially for [[foot bath]]s to soothe sore feet.  Such baths have been claimed to also soothe and hasten recovery of muscle pain, soreness, or injury.  However, these claims have not been scientifically confirmed.> The main benefit of the salt is cosmetic: it prevents the temporary skin wrinkling caused by prolonged immersion in plain water. <ref name=ingra2016/> <ref name=wsjdXXXX/>  It is also the usual component of the solution used in [[isolation tank]]s. 

In the [[United Kingdom|UK]], a medication containing magnesium sulphate and [[phenol]], called "drawing paste", is claimed to be useful for small boils or localised infections,<ref name=boots2018/> and removing splinters.<ref name=splinter/>

Internally, magnesium sulfate may be administered by oral, respiratory, or [[intravenous magnesium|intravenous]] routes.  Internal uses include: replacement therapy for [[magnesium deficiency]],<ref name=rxmed2009/> treatment of acute and severe [[arrhythmia]]s,<ref heart2016/> as a [[bronchodilator]] in the treatment of [[asthma]],<ref name=blitz2005/> and preventing [[eclampsia]].<ref name=duley2010/>

===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 [[potato]]es, [[tomato]]es, [[carrot]]s, [[Capsicum|peppers]], [[lemons]], and [[rose]]s. The advantage of magnesium sulfate over other magnesium [[soil amendment]]s (such as [[Dolomite (mineral)|dolomitic lime]]) is its high [[solubility]], which also allows the option of [[foliar feeding]]. Solutions of magnesium sulfate are also nearly pH 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.<ref name=pubchem/>

===Food preparation===
Magnesium sulfate is used as a brewing salt in making [[beer]].<ref name=brew2016/> It may also be used as a coagulant for making [[tofu]].<ref name=matsu2000/>

===Chemistry===
[[Anhydrous]] magnesium sulfate is commonly used as a [[desiccant]] in organic synthesis due to its affinity for [[water]] and compatibility with most organic compounds. During [[work-up (chemistry)|work-up]], an organic phase is treated with anhydrous magnesium sulfate. The hydrated solid is then removed with filtration, decantation or distillation (if the boiling point is low enough). Other inorganic sulfate salts such as [[sodium sulfate]] and [[calcium sulfate]] may be used in the same way.

===Construction===
Magnesium sulfate is used to prepare specific cements by the reaction between magnesium oxide and magnesium sulfate solution, which are of good binding ability and more resistance than Portland cement. This cement is mainly adopted in the production of lightweight insulation panels. Weakness in water resistance limits its usage.

Magnesium (or sodium) sulfate is also used for testing aggregates for soundness in accordance with ASTM C88 standard, when there are no service records of the material exposed to actual weathering conditions. The test is accomplished by repeated immersion in saturated solutions followed by oven drying to dehydrate the salt precipitated in permeable pore spaces. The internal expansive force, derived from the rehydration of the salt upon re-immersion, simulates the expansion of water on freezing.

===Aquaria===
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.<ref name=aqua2006/>

==Double salts==
[[Double salts]] containing magnesium sulfate exist.  There are several known as [[sodium magnesium sulfate]]s and [[Potassium magnesium sulfate (disambiguation)|potassium magnesium sulfates]]<!--intentional link to DAB page-->.  A mixed [[copper]]-magnesium sulfate heptahydrate (Mg,Cu)SO<sub>4</sub>·7H<sub>2</sub>O was recently found to occur in mine tailings,and has been given the mineral name [[alpersite]].<ref name=pete2006/>

==Safety==
An abnormally elevated plasma concentration of magnesium is called [[hypermagnesemia]].

==See also==
* [[Calcium sulfate]] 

==References==
<references>

<ref name=buch2000>Industrial Inorganic Chemistry, Karl Heinz Büchel, Hans-Heinrich Moretto, Dietmar Werner, John Wiley & Sons, 2d edition, 2000, {{ISBN|978-3-527-61333-5}}</ref>

<ref name=pubchem>{{cite web|title=Pubchem: magnesium sulfate|url=https://pubchem.ncbi.nlm.nih.gov/compound/magnesium_sulfate#section=Chemical-and-Physical-Properties|url-status=live|archiveurl=https://web.archive.org/web/20161018220642/https://pubchem.ncbi.nlm.nih.gov/compound/magnesium_sulfate#section=Chemical-and-Physical-Properties|archivedate=18 October 2016}}</ref>

<ref name=brew2016>{{Cite web|url=https://nationalhomebrew.com.au/beer/brewing-adjuncts-and-beer-enhancers/national-home-brew-magnesium-sulphate|title=Magnesium Sulphate|website=National Home Brew|archive-url=https://web.archive.org/web/20160801040013/https://nationalhomebrew.com.au/beer/brewing-adjuncts-and-beer-enhancers/national-home-brew-magnesium-sulphate|archive-date=August 1, 2016|access-date=January 4, 2019}}</ref>

<ref name=matsu2000>{{cite patent |inventor-last= Matsuura |inventor-first= Masaru |inventor2-last= Sasaki |inventor2-first= Masaoki |inventor3-last= Sasakib |inventor3-first= Jun |inventor4-last=Takeuchi |inventor4-first= Tomok |date= 28 Mar 2000 |title= Process for producing packed tofu |country-code= US |description= 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. |patent-number= 6042851 }}</ref>

<ref name=aqua2006>{{cite web|url = http://reefkeeping.com/issues/2006-07/rhf/index.php|title = Do-It-Yourself Magnesium Supplements for the Reef Aquarium|year = 2006|publisher = Reefkeeping|accessdate = 2008-03-14|url-status = live|archiveurl = https://web.archive.org/web/20080322114524/http://www.reefkeeping.com/issues/2006-07/rhf/index.php|archivedate = 22 March 2008}}</ref>

<ref name=sanc2015>{{cite journal | title = Ammoniated phyllosilicates with a likely outer Solar System origin on (1) Ceres |author1=M. C. De Sanctis |author2=E. Ammannito |author3=A. Raponi |author4=S. Marchi |author5=T. B. McCord |author6=H. Y. McSween |author7=F. Capaccioni |author8=M. T. Capria |author9=F. G. Carrozzo |author10=M. Ciarniello |author11=A. Longobardo |author12=F. Tosi |author13=S. Fonte |author14=M. Formisano |author15=A. Frigeri |author16=M. Giardino |author17=G. Magni |author18=E. Palomba |author19=D. Turrini |author20=F. Zambon |author21=J.-P. Combe |author22=W. Feldman |author23=R. Jaumann |author24=L. A. McFadden |author25=C. M. Pieters | journal = Nature | volume = 528 |issue=7581 | pages = 241–244 | date = 2015 | doi=10.1038/nature16172 | pmid=26659184|url=https://elib.dlr.de/101182/1/apf314pc_20151215_152518.pdf }}</ref>

<ref name=pete2006>{{cite journal |title=Alpersite (Mg,Cu)SO<sub>4</sub>·7H<sub>2</sub>O, a new mineral of the melanterite group, and cuprian pentahydrite: Their occurrence within mine waste |first1=Ronald C. |last1=Peterson |first2=Jane M. |last2=Hammarstrom |first3=Robert R |last3=Seal, II |journal=American Mineralogist |date=Feb 2006 |volume=91 |pages=261–269 |doi=10.2138/am.2006.1911 |issue=2–3}}</ref>

<ref name=odoc1995>{{cite journal | last1 = Odochian | first1 = Lucia | year = 1995| title = Study of the nature of the crystallization water in some magnesium hydrates by thermal methods | url = http://resources.metapress.com/pdf-preview.axd?code=3q44807116q07153&size=largest | journal = Journal of Thermal Analysis and Calorimetry | volume = 45| issue = 6| pages = 1437–1448| doi = 10.1007/BF02547437 }}</ref>

<ref name=boots2018>{{cite web|title=Boots Magnesium Sulfate Paste B.P. - Patient Information Leaflet (PIL) - (eMC)|url=https://www.medicines.org.uk/emc/product/8327|website=www.medicines.org.uk|accessdate=14 April 2018|language=en}}</ref>

<ref name=splinter>{{Cite web | url=http://www.tipking.co.uk/tip/5929.html | title=Removing a splinter with Magnesium Sulphate}}</ref>

<ref name=ingra2016>{{cite web|last1=Ingraham|first1=Paul|title=Does Epsom Salt Work? The science of Epsom salt bathing for recovery from muscle pain, soreness, or injury|url=https://www.painscience.com/articles/epsom-salts.php|website=Pain Science|accessdate=29 August 2016|url-status=live|archiveurl=https://web.archive.org/web/20160910223001/https://www.painscience.com/articles/epsom-salts.php|archivedate=10 September 2016}}</ref>

<ref name=wsjdXXXX>{{cite news|url=https://www.wsj.com/articles/SB10001424052702303302504577327722133289222 |title=Quick Cures/Quack Cures: Is Epsom Worth Its Salt? |newspaper=[[Wall Street Journal]] |date=April 9, 2012 |accessdate=June 15, 2019 |url-status=live |archiveurl=https://web.archive.org/web/20120412091100/https://online.wsj.com/article/SB10001424052702303302504577327722133289222.html |archivedate=12 April 2012 }}</ref>

<ref name=rxmed2009>{{cite web|url=http://www.rxmed.com/b.main/b2.pharmaceutical/b2.1.monographs/CPS-%20Monographs/CPS-%20(General%20Monographs-%20M)/MAGNESIUM%20SULFATE.html|title=Pharmaceutical Information – Magnesium Sulfate|publisher=RxMed|accessdate=2009-07-06|url-status=live|archiveurl=https://web.archive.org/web/20090403180025/http://www.rxmed.com/b.main/b2.pharmaceutical/b2.1.monographs/CPS-%20Monographs/CPS-%20(General%20Monographs-%20M)/MAGNESIUM%20SULFATE.html|archivedate=3 April 2009}}</ref>

<ref heart2016>{{cite web|title=CPR and First Aid: Antiarrhythmic Drugs During and Immediately After Cardiac Arrest (section)|url=https://eccguidelines.heart.org/index.php/circulation/cpr-ecc-guidelines-2/part-7-adult-advanced-cardiovascular-life-support/?strue=1&id=5-3-2-1|publisher=American Heart Association|accessdate=29 August 2016|quote=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.}}</ref>

<ref name=blitz2005>{{cite journal | vauthors = Blitz M, Blitz S, Hughes R, Diner B, Beasley R, Knopp J, Rowe BH | title = Aerosolized magnesium sulfate for acute asthma: a systematic review | journal = Chest | year = 2005 | volume = 128 | pages = 337–344 | doi = 10.1378/chest.128.1.337 | pmid = 16002955 | issue = 1 }}.</ref>

<ref name=duley2010>{{cite journal|last1=Duley|first1=L|last2=Gülmezoglu|first2=AM|last3=Henderson-Smart|first3=DJ|last4=Chou|first4=D|title=Magnesium sulphate and other anticonvulsants for women with pre-eclampsia.|journal=The Cochrane Database of Systematic Reviews|date=Nov 10, 2010|issue=11|pages=CD000025|pmid=21069663|doi=10.1002/14651858.CD000025.pub2|pmc=7061250}}</ref>

</references>

==External links==
* [https://www.ilo.org/dyn/icsc/showcard.display?p_lang=en&p_card_id=1197&p_version=2 International Chemical Safety Cards—Magnesium Sulfate]

<div style="overflow:auto;">
{{Magnesium compounds}}
{{Laxatives}}
{{Mineral supplements}}
{{B03, B05, B06}}
{{Antiarrhythmic agents}}
{{Other dermatological preparations}}
{{Other gynecologicals}}
{{Diagnostic agents}}
{{Sulfates}}
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{{DEFAULTSORT:Magnesium Sulfate}}
[[Category:Desiccants]]
[[Category:Laxatives]]
[[Category:Magnesium compounds]]
[[Category:Sulfates]]