View source for Magnesium sulfate

{{Short description|Chemical compound with formula MgSO<sub>4</sub>}}
{{About|the chemical compound|medical uses|Magnesium sulfate (medical use)}}
{{Use dmy dates|date=July 2020}}
{{chembox
| Verifiedfields = changed
| Watchedfields  = changed
| verifiedrevid  = 476997098
| Name           = Magnesium sulfate
| ImageFile1     = Mgaq6SO4.svg
| ImageCaption1  = Magnesium sulfate hexahydrate
| ImageFile2     = Magnesium sulfate anhydrous.jpg
| ImageCaption2  = Anhydrous magnesium sulfate
| ImageFile3     = Magnesium sulfate.JPG
| ImageCaption3  = [[Epsomite]] (Magnesium sulfate heptahydrate)
| IUPACName      = Magnesium sulfate
| OtherNames     = {{ubl|Epsom salt (Magnesium sulfate heptahydrate)|English salt|Bitter salts|Bath salt}}
| Section1       = {{Chembox Identifiers
| UNII_Ref = {{fdacite|correct|FDA}}
| UNII = ML30MJ2U7I
| UNII1_Ref = {{fdacite|correct|FDA}}
| UNII1 = E2L2TK027P
| UNII1_Comment = (monohydrate)
| UNII2_Ref = {{fdacite|correct|FDA}}
| UNII2 = SK47B8698T
| UNII2_Comment = (heptahydrate)
| ChEMBL_Ref = {{ebicite|changed|EBI}}
| ChEMBL = 2021423
| ChEMBL5 = 3989857
| ChEMBL5_Comment = (heptahydrate)
| InChI = 1/Mg.8H2O4S/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
| ChEBI5 = 31795
| ChEBI5_Comment = (heptahydrate)
| EINECS =  231-298-2
| KEGG5 = C12505
| KEGG5_Comment = (heptahydrate)
| 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|CAS}}
| 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|CAS}}
| CASNo5 = 10034-99-8
| CASNo5_Comment = (heptahydrate)
| ChemSpiderID_Ref = {{chemspidercite|correct|chemspider}}
| ChemSpiderID = 22515
| PubChem = 24083
| RTECS = OM4500000
| 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
 }}
| Section2       = {{Chembox Properties
| Formula = {{chem2|MgSO4}}
| Appearance = white crystalline solid
| Odor = odorless
| Density = {{ubl|2.66 g/cm<sup>3</sup> (anhydrous)|2.445 g/cm<sup>3</sup> (monohydrate)|1.68 g/cm<sup>3</sup> (heptahydrate)|1.512 g/cm<sup>3</sup> (undecahydrate)}}
| MolarMass = {{ubl|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)}}
| SolubilityProduct = 738 (502 g/L)
| Solubility = {{ubl|''anhydrous''|26.9 g/(100 mL) (0&nbsp;°C)|35.1 g/(100 mL) (20&nbsp;°C)|50.2 g/(100 mL) (100&nbsp;°C)|<hr />|''heptahydrate''|113 g/(100 mL) (20&nbsp;°C)}}
| SolubleOther = {{ubl|1.16 g/(100 mL) (18&nbsp;°C, [[diethyl ether|ether]])|slightly soluble in [[ethanol|alcohol]], [[glycerol]]|insoluble in [[acetone]]}}
| MeltingPt = {{ubl|anhydrous decomposes at 1,124&nbsp;°C|monohydrate decomposes at 200&nbsp;°C|heptahydrate decomposes at 150&nbsp;°C|undecahydrate decomposes at 2&nbsp;°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
| NFPA-H = 1
| NFPA-F = 0
| NFPA-R = 0
 }}
| Section8       = {{Chembox Related
| OtherCations = {{ubl|[[Beryllium sulfate]]|[[Calcium sulfate]]|[[Strontium sulfate]]|[[Barium sulfate]]|[[Iron(II) sulfate]]|[[Copper(II) sulfate]]}}
| OtherCompounds =
 }}
}}
'''Magnesium sulfate''' or '''magnesium sulphate''' (in English-speaking countries other than the US) is a [[chemical compound]], a [[salt (chemistry)|salt]] with the formula {{chem2|MgSO4}}, consisting of [[magnesium]] [[cation]]s {{chem2|Mg(2+)}} (20.19% by mass) and [[sulfate]] [[anion]]s {{chem2|SO4(2-)}}. It is a white [[Crystal|crystalline solid]], [[Solubility|soluble]] in water but not in [[ethanol]].

Magnesium sulfate is usually encountered in the form of a [[water of crystallization|hydrate]] {{chem2|MgSO4*''n''H2O}}, for various values of ''n'' between 1 and 11. The most common is the heptahydrate {{chem2|MgSO4*7H2O}}, known as '''[[Epsomite|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 deficient in magnesium (an essential [[Plant nutrition|plant nutrient]] because of the role of magnesium in [[chlorophyll]] and [[photosynthesis]]). The monohydrate is favored for this use; by the mid 1970s, its production was 2.3 million tons per year.<ref name=buch2000/> The [[hydrate|anhydrous]] form and several hydrates occur in nature as [[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 [[hydrate]]s, including:
* Anhydrous, {{chem2|MgSO4}}; unstable in nature, hydrates to form [[epsomite]].<ref>{{Cite web|url=https://www.mindat.org/min-40082.html|title=Magnesium Sulphate: Mineral information, data and localities}}</ref>
* Monohydrate, {{chem2|MgSO4*H2O}}; [[kieserite]], [[monoclinic]].<ref name=odoc1995/>
* Monohydrate, {{chem2|MgSO4*H2O}}; [[Triclinic crystal system|triclinic]].<ref name="Meusburger-2020" />
* {{chem2|MgSO4*1.25H2O}} or {{chem2|4MgSO4*5H2O}}.<ref name=fort2012/>
* Dihydrate, {{chem2|MgSO4*2H2O}}; [[Orthorhombic crystal system|orthorhombic]].
* {{chem2|MgSO4*2.5H2O}} or {{chem2|2MgSO4*5H2O}}.<ref name=fort2012/>
* Trihydrate, {{chem2|MgSO4*3H2O}}.<ref name=fort2012/>
* Tetrahydrate, {{chem2|MgSO4*4H2O}}; [[starkeyite]], [[Monoclinic crystal system|monoclinic]].<ref name=pete2007/>
* Pentahydrate, {{chem2|MgSO4*5H2O}}; [[pentahydrite]], [[triclinic]].<ref name=odoc1995/>
* Hexahydrate, {{chem2|MgSO4*6H2O}}; hexahydrite, monoclinic.
* Heptahydrate, {{chem2|MgSO4*7H2O}} ("Epsom salt"); [[epsomite]], orthorhombic.<ref name=odoc1995/>
* Enneahydrate, {{chem2|MgSO4*9H2O}}, monoclinic.<ref name=fort2017/>
* Decahydrate, {{chem2|MgSO4*10H2O}}.<ref name=pete2007/>
* Undecahydrate, {{chem2|MgSO4*11H2O}}; [[meridianiite]], triclinic.<ref name=pete2007/>

As of 2017, the existence of the decahydrate apparently has not been confirmed.<ref name=fort2017/>

All the hydrates lose water upon heating. Above 320&nbsp;°C, only the anhydrous form is stable. It decomposes without [[melting]] at 1124&nbsp;°C into [[magnesium oxide]] (MgO) and [[sulfur trioxide]] ({{chem2|SO3}}).

===Heptahydrate===
{{anchor|Epsomite|Epsom salt}}
{{main|Epsomite|Magnesium sulfate (medical use)}}

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 medium|porous]] [[chalk]] of the [[North Downs]] meets the [[Permeability (Earth sciences)|impervious]] [[London Clay|London clay]].

The heptahydrate readily loses one equivalent of water to form the hexahydrate.

It is a natural source of both magnesium and [[Sulfur|sulphur]]. Epsom salts are commonly used in [[bath salts]], [[Exfoliation (cosmetology)|exfoliants]], muscle relaxers and pain relievers. However, these are different from Epsom salts that are used for gardening, as they contain [[Odor|aromas]] and [[perfume]]s not suitable for plants.<ref>{{Cite web |title=What Is Epsom Salt And Why Is It So Important For My Cannabis Garden? |url=https://herbiesheadshop.com/blog/what-is-epsom-salt-and-why-is-it-so-important-for-my-cannabis-garden |access-date=2020-10-28 |website=Herbies}}</ref>

===Monohydrate===
{{main|Kieserite}}

Magnesium sulfate monohydrate, or kieserite, can be prepared by heating the heptahydrate to 120&nbsp;°C.<ref name="PubChem">{{Cite web |last=PubChem |title=Hazardous Substances Data Bank (HSDB) : 664 |url=https://pubchem.ncbi.nlm.nih.gov/source/hsdb/664#section=Density&fullscreen=true |access-date=2022-03-15 |website=pubchem.ncbi.nlm.nih.gov |language=en}}</ref> Further heating to 250&nbsp;°C gives anhydrous magnesium sulfate.<ref name="PubChem" /> Kieserite exhibits monoclinic symmetry at pressures lower than 2.7 GPa after which it transforms to phase of triclinic symmetry.<ref name="Meusburger-2020">{{Cite journal |last=Meusburger |first=Johannes |date=15 January 2020 |title=Polymorphism of Mg-sulfate monohydrate kieserite under pressure and its occurrence on giant icy jovian satellites |journal=Icarus |volume=336 |page=113459 |doi=10.1016/j.icarus.2019.113459 |s2cid=209977442 |url=https://www.sciencedirect.com/science/article/pii/S0019103519304129}}</ref>

===Undecahydrate===
The undecahydrate {{chem2|MgSO4*11H2O}}, [[meridianiite]], is stable at [[atmospheric pressure]] only below 2&nbsp;°C. Above that temperature, it liquefies into a mix of solid heptahydrate and a [[Solubility|saturated solution]]. It has a [[eutectic]] point with water at −3.9&nbsp;°C and 17.3% (mass) of {{chem2|MgSO4}}.<ref name=fort2012/> Large [[crystal]]s can be obtained from solutions of the proper concentration kept at 0&nbsp;°C for a few days.<ref name=fort2012/>

At pressures of about 0.9 [[gigapascal|GPa]] and at 240 [[kelvin|K]], meridianiite decomposes into a mixture of [[ice VI]] and the enneahydrate {{chem2|MgSO4*9H2O}}.<ref name=fort2017/>

===Enneahydrate===
The enneahydrate {{chem2|MgSO4*9H2O}} was identified and characterized only recently, even though it seems easy to produce (by cooling a solution of {{chem2|MgSO4}} and [[sodium sulfate]] {{chem2|Na2SO4}} in suitable proportions).

The structure is monoclinic, with unit-cell parameters at 250 K: ''a''&nbsp;= 0.675&nbsp;[[nanometer|nm]], ''b''&nbsp;= 1.195&nbsp;nm, ''c''&nbsp;= 1.465&nbsp;nm, β = 95.1°, ''V'' = 1.177&nbsp;nm<sup>3</sup> with ''Z''&nbsp;= 4. The most probable space group is P21/c. [[Magnesium selenate]] also forms an enneahydrate {{chem2|MgSeO4*9H2O}}, but with a different crystal structure.<ref name=fort2017/>

==Natural occurrence==
As {{chem2|Mg(2+)}} and {{chem2|SO4(2-)}} ions are respectively the second most abundant [[cation]] and [[anion]] present in [[seawater]] after {{chem2|Na+}} and {{chem2|Cl-}}, 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 [[Evaporite|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 {{chem2|MgSO4}} are hydrates. [[Epsomite]] is the natural analogue of "Epsom salt". [[Meridianiite]], {{chem2|MgSO4*11H2O}}, has been observed on the surface of frozen lakes and is thought to also occur on Mars. [[Hexahydrite]] is the next lower 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 [[Damp (mining)|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]], {{chem2|MgCO3}}) or [[periclase|magnesia]] ([[magnesium oxide|oxide]], MgO) with [[sulfuric acid]] ({{chem2|H2SO4}}):

: {{chem2|H2SO4 + MgCO3 -> MgSO4 + H2O + CO2}}

Another possible method is to treat seawater or magnesium-containing industrial wastes so as to precipitate [[magnesium hydroxide]] and react the [[Precipitation (chemistry)|precipitate]] with [[sulfuric acid]].

Also, magnesium sulfate heptahydrate ([[epsomite]], {{chem2|MgSO4*7H2O}}) is manufactured by dissolution of magnesium sulfate monohydrate ([[kieserite]], {{chem2|MgSO4*H2O}}) in water and subsequent crystallization of the heptahydrate.

==Physical properties==
Magnesium sulfate [[Relaxation (physics)|relaxation]] is the primary mechanism that causes the absorption of [[Underwater acoustics|sound]] in [[seawater]] at [[Frequency|frequencies]] above 10&nbsp;[[Hertz|kHz]]<ref>{{cite web |url=http://resource.npl.co.uk/acoustics/techguides/seaabsorption/physics.html |title=Underlying physics and mechanisms for the absorption of sound in seawater |publisher=Resource.npl.co.uk |access-date=2009-07-06 |url-status=live |archive-url=https://web.archive.org/web/20090618070030/http://resource.npl.co.uk/acoustics/techguides/seaabsorption/physics.html |archive-date=18 June 2009 |df=dmy-all }}</ref> ([[acoustic energy]] is converted to [[thermal energy]]). Lower frequencies are less absorbed by the salt, so that low frequency sound travels farther in the ocean. [[Boric acid]] and [[magnesium carbonate]] also contribute to absorption.<ref>Michael A. Ainslie, Principles of Sonar Performance Modeling, p.18</ref>

==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 from muscle pain, soreness, or injury.<ref name=ingra2016/> Potential health effects of magnesium sulfate are reflected in medical studies on the impact of magnesium on resistant depression<ref>{{Cite journal|last1=Eby|first1=George A.|last2=Eby|first2=Karen L.|date=April 2010|title=Magnesium for treatment-resistant depression: a review and hypothesis |url=https://pubmed.ncbi.nlm.nih.gov/19944540/ |journal=Medical Hypotheses |volume=74 |issue=4 |pages=649–660 |doi=10.1016/j.mehy.2009.10.051 |issn=1532-2777|pmid=19944540}}</ref> and as an analgesic for migraine and chronic pain.<ref>{{Citation needed|reason=Cited article "https://www.ncbi.nlm.nih.gov/books/NBK475794/" fails to support this claim, stating instead "Definitive conclusions on the effectiveness of magnesium (as magnesium sulfate, administered intravenously) compared to placebo for treatment of migraine were not possible."|date=June 2022}}</ref> Magnesium sulfate has been studied in the treatment of [[asthma]],<ref>{{Cite web|title=Magnesium sulfate asthma – Search Results |url=https://pubmed.ncbi.nlm.nih.gov/?term=magnesium+sulfate+asthma |access-date=2021-06-29 |publisher=PubMed |language=en}}</ref> [[Pre-eclampsia|preeclampsia]] and [[eclampsia]].<ref>{{Cite web|title=Magnesium sulfate eclampsia – Search Results |url=https://pubmed.ncbi.nlm.nih.gov/?term=magnesium+sulfate+eclampsia |access-date=2021-06-29 |publisher=PubMed|language=en}}</ref>

Magnesium sulfate is the usual component of the concentrated salt solution used in [[isolation tank]]s to increase its [[specific gravity]] to approximately 1.25–1.26. This high density allows an individual to float effortlessly on the surface of water in the closed tank, eliminating as many of the external senses as possible.

In the [[United Kingdom|UK]], a medication containing magnesium sulfate and [[phenol]], called "drawing paste", is useful for small boils or localized 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 name=heart2016/> as a [[bronchodilator]] in the treatment of [[asthma]],<ref name=blitz2005/> preventing [[eclampsia]]<ref name="duley2010" /> and [[cerebral palsy]],<ref>{{Cite journal |last1=Edwards |first1=Hannah B |last2=Redaniel |first2=Maria Theresa |last3=Sillero-Rejon |first3=Carlos |last4=Margelyte |first4=Ruta |last5=Peters |first5=Tim J |last6=Tilling |first6=Kate |last7=Hollingworth |first7=William |last8=McLeod |first8=Hugh |last9=Craggs |first9=Pippa |last10=Hill |first10=Elizabeth |last11=Redwood |first11=Sabi |last12=Donovan |first12=Jenny |last13=Treloar |first13=Emma |last14=Wetz |first14=Ellie |last15=Swinscoe |first15=Natasha |date=2023-01-08 |title=National PReCePT Programme: a before-and-after evaluation of the implementation of a national quality improvement programme to increase the uptake of magnesium sulfate in preterm deliveries |journal=Archives of Disease in Childhood - Fetal and Neonatal Edition |volume=108 |issue=4 |language=en |pages=fetalneonatal–2022–324579 |doi=10.1136/archdischild-2022-324579 |pmid=36617442 |pmc=10314002 |issn=1359-2998|hdl=1983/5a362df9-c182-4bae-96c5-60c76b6219a1 |hdl-access=free }}</ref><ref>{{Cite journal |date=30 June 2023 |title=NHS quality improvement programme reduces the risk of cerebral palsy in newborns |url=https://evidence.nihr.ac.uk/alert/nhs-quality-improvement-programme-reduces-risk-cerebral-palsy-newborns/ |journal=NIHR Evidence|doi=10.3310/nihrevidence_58371 }}</ref> a [[tocolytic]] agent,<ref name="pubchem" /> and as an [[anticonvulsant]].<ref name="pubchem" />

It also may be used as [[laxative]].<ref>{{Cite journal |last1=Izzo |first1=A. A. |last2=Gaginella |first2=T. S. |last3=Capasso |first3=F. |date=June 1996 |title=The osmotic and intrinsic mechanisms of the pharmacological laxative action of oral high doses of magnesium sulphate. Importance of the release of digestive polypeptides and nitric oxide |url=https://pubmed.ncbi.nlm.nih.gov/8878010/ |journal=Magnesium Research |volume=9 |issue=2 |pages=133–138 |issn=0953-1424 |pmid=8878010}}</ref>

===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 the [[Alkali soil|slightly 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/> Contrary to the popular belief that magnesium sulfate is able to control pests and slugs, helps seeds germination, produce more flowers, improve nutrient uptake, and is environmentally friendly, it does none of the purported claims except for correcting magnesium deficiency in soils. Magnesium sulfate can even pollute water if used in excessive amounts.<ref>{{Cite web|title=Horticulture myths|url=http://www.uvm.edu/pss/ppp/articles/myths.html|url-status=live|archive-url=https://web.archive.org/web/20190807145520/http://www.uvm.edu/pss/ppp/articles/myths.html|archive-date=7 August 2019|access-date=18 October 2021|website=University of Vermont Extension Department of Plant and Soil Science}}</ref>

Magnesium sulfate was historically used as a treatment for [[lead poisoning]] prior to the development of [[chelation therapy]], as it was hoped that any lead ingested would be precipitated out by the magnesium sulfate and subsequently purged from the [[Human digestive system|digestive system]].<ref name=hcwood/> This application saw particularly widespread use among veterinarians during the early-to-mid 20th century; Epsom salt was already available on many farms for agricultural use, and it was often prescribed in the treatment of farm animals that inadvertently ingested lead.<ref name=Barker1945/><ref name=herriot/>

===Food preparation===
Magnesium sulfate is used as:
* [[Brewing]] salt in making [[beer]]<ref name=brew2016/>
* [[Coagulation (water treatment)|Coagulant]] for making [[tofu]]<ref name=matsu2000/>
* [[Salt substitute]]

===Chemistry===
[[Anhydrous]] magnesium sulfate is commonly used as a [[desiccant]] in [[organic synthesis]] owing 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 by [[filtration]], [[decantation]], or by [[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 [[cement]]s 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 utilized in the production of lightweight insulation panels, although it's poor water resistance limits its usage.

Magnesium (or sodium) sulfate is also used for testing [[Construction aggregate|aggregates]] for soundness in accordance with [[ASTM International|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 [[Porosity|pore spaces]]. The internal expansive force, derived from the rehydration of the salt upon re-immersion, simulates the expansion of water on [[freezing]].

Magnesium sulfate is also used to test the resistance of [[concrete]] to external [[sulfate attack]] (ESA).

===Aquaria===
Magnesium sulfate heptahydrate is also used to maintain the magnesium concentration in marine aquaria which contain large amounts of [[Scleractinia|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 [[Saline water|saltwater]] and prevent their spontaneous [[Precipitation (chemistry)|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 {{chem2|(Mg,Cu)SO4*7H2O}} was found to occur in [[Tailings|mine tailings]] and was given the mineral name [[alpersite]].<ref name=pete2006/>

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

==References==
{{reflist|refs=
<ref name="fort2017">A. Dominic Fortes, Kevin S. Knight, and Ian G. Wood (2017): "Structure, thermal expansion and incompressibility of MgSO<sub>4</sub>·9H<sub>2</sub>O, its relationship to meridianiite (MgSO<sub>4</sub>·11H<sub>2</sub>O) and possible natural occurrences". ''Acta Crystallographica Section B: Structureal Science, Crystal Engineering and Materials'', volume 73, part 1, pages 47-64. {{doi|10.1107/S2052520616018266}}</ref>
<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|url-status=live|archive-url=https://web.archive.org/web/20210429232549/https://pubchem.ncbi.nlm.nih.gov/compound/Magnesium-sulfate|archive-date=29 April 2021|access-date=13 September 2021|website=PubChem}}</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=1 August 2016|access-date=4 January 2019}}</ref>
<ref name="matsu2000">{{cite patent |inventor1-last= Matsuura |inventor1-first= Masaru |inventor2-last= Sasaki |inventor2-first= Masaoki |inventor3-last= Sasakib |inventor3-first= Jun |inventor4-last=Takeuchi |inventor4-first= Tomok |pubdate= 2000-03-28 |title= Process for producing packed tofu |country= US |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|access-date = 2008-03-14|url-status = live|archive-url = https://web.archive.org/web/20080322114524/http://www.reefkeeping.com/issues/2006-07/rhf/index.php|archive-date = 22 March 2008}}</ref>
<ref name="pete2007">R. C. Peterson, W. Nelson, B. Madu, and H. F. Shurvell (2007): "Meridianiite: A new mineral species observed on Earth and predicted to exist on Mars". ''American Mineralogist'', volume 92, issue 10, pages 1756–1759. {{doi|10.2138/am.2007.2668}}</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|bibcode=2015Natur.528..241D |s2cid=1687271 |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|s2cid=56431885 }}</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 | s2cid = 97855885 | access-date = 7 August 2010 | archive-url = https://web.archive.org/web/20110826021910/http://resources.metapress.com/pdf-preview.axd?code=3q44807116q07153&size=largest | archive-date = 26 August 2011 | url-status = dead }}</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|access-date=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|access-date=29 August 2016|url-status=live|archive-url=https://web.archive.org/web/20160910223001/https://www.painscience.com/articles/epsom-salts.php|archive-date=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=[[The Wall Street Journal]]|date=9 April 2012 |access-date=15 June 2019 |url-status=dead |archive-url=https://web.archive.org/web/20120412091100/https://online.wsj.com/article/SB10001424052702303302504577327722133289222.html |archive-date=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|access-date=2009-07-06|url-status=live|archive-url=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|archive-date=3 April 2009}}</ref>
<ref name="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|access-date=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=10 November 2010|volume=2010|issue=11|pages=CD000025|pmid=21069663|doi=10.1002/14651858.CD000025.pub2|pmc=7061250}}</ref>
<ref name="fort2012">A. Dominic Fortes, Frank Browning, and Ian G. Wood (2012): "Cation substitution in synthetic meridianiite (MgSO<sub>4</sub>·11H<sub>2</sub>O) I: X-ray powder diffraction analysis of quenched polycrystalline aggregates". ''Physics and Chemistry of Minerals'', volume 39, issue, pages 419–441. {{doi|10.1007/s00269-012-0497-9}}</ref>
<ref name="hcwood">{{cite book |last=Wood |first=H. C. |author-link=Horatio C. Wood Jr. |date=1877 |title=A Treatise on Therapeutics, Comprising Materia Medica and Toxicology, with Especial Reference to the Application of the Physiological Action of Drugs to Clinical Medicine |url=https://books.google.com/books?id=pjpHAQAAMAAJ&pg=PA34 |location=Philadelphia |publisher=[[J. B. Lippincott & Co.]] |page=34 |quote=The treatment of acute lead-poisoning consists in the evacuation of the stomach, if necessary, the exhibition of the sulphate of sodium or of magnesium, and the meeting of the indications as they arrive. The Epsom and Glauber's salts act as chemical antidotes, by precipitating the insoluble sulphate of lead, and also, if in excess, empty the bowel of the compound formed.}}</ref>
<ref name="Barker1945">{{cite journal |last=Barker |first=C. A. V. |date=January 1945 |title=Experience with Lead Poisoning |journal=Canadian Journal of Comparative Medicine and Veterinary Science |volume=9 |issue=1 |pages=6–8 |pmc=1660962 |pmid=17648099 |quote=Udall (1) suggests sodium citrate as of some value together with Epsom salts which will bring about a precipitation of the lead in the form of an insoluble compound. Nelson (3) reported a case that survived following the use of a 20% magnesium sulphate solution intravenously, subcutaneously and orally. McIntosh (5) has suggested that purgative doses of Epsom salts may be effective in combining with the lead and overcoming the toxicity.}}</ref>
<ref name="herriot">{{cite book |last=Herriot |first=James |author-link=James Herriot |date=1972 |title=All Creatures Great and Small |url=https://books.google.com/books?id=Hm-St_CUgsIC&pg=PA157 |location=New York |publisher=[[St. Martin's Press]] |page=157 |quote=The specific antidotes to metal poisoning had not been discovered and the only thing which sometimes did a bit of good was magnesium sulphate which caused the precipitation of insoluble lead sulphate. The homely term for magnesium sulphate is, of course, epsom salts. |isbn=0-312-08498-6}}</ref>
}}

==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]

{{Magnesium compounds}}
{{Sulfates}}
{{Emergency medicine}}
{{Authority control}}

{{DEFAULTSORT:Magnesium Sulfate}}
[[Category:Desiccants]]
[[Category:Laxatives]]
[[Category:Magnesium compounds]]
[[Category:Sulfates]]