Magnesium sulfate

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Not to be confused with Magnesium sulfide.
Magnesium sulfate
Magnesium sulfate anhydrous.jpg
Anhydrous magnesium sulfate
Magnesium sulfate.JPG
Epsomite (heptahydrate)
Identifiers
CAS number 7487-88-9 YesY, 14168-73-1 (monohydrate), 24378-31-2 (tetrahydrate), 15553-21-6 (pentahydrate), 13778-97-7 (hexahydrate), 10034-99-8 (heptahydrate)
PubChem 24083
ChemSpider 22515 YesY
UNII ML30MJ2U7I YesY
DrugBank DB00653
ChEBI CHEBI:32599 YesY
ChEMBL CHEMBL1200456 N
RTECS number OM4500000
ATC code A06AD04,A12CC02 B05XA05 D11AX05 V04CC02
Jmol-3D images Image 1
Properties
Molecular formula MgSO4
Molar mass 120.366 g/mol (anhydrous)
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 1124 °C

monohydrate decomposes at 200 °C
heptahydrate decomposes at 150 °C
undecahydrate decomposes at 2 °C

Solubility in water anhydrous
26.9 g/100 mL (0 °C)
25.5 g/100 mL (20 °C)
50.2 g/100 mL (100 °C)
heptahydrate
71 g/100 mL (20 °C)
Solubility 1.16 g/100 mL (18 °C, ether)
slightly soluble in alcohol, glycerol
insoluble in acetone
Refractive index (nD) 1.523 (monohydrate)
1.433 (heptahydrate)
Structure
Crystal structure monoclinic (hydrate)
Hazards
MSDS External MSDS
EU Index Not listed
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
Related compounds
Other cations Beryllium sulfate
Calcium sulfate
Strontium sulfate
Barium sulfate
Except where noted otherwise, data are given for materials in their standard state (at 25 °C (77 °F), 100 kPa)
 N (verify) (what is: YesY/N?)
Infobox references

Magnesium sulfate (or magnesium sulphate) is an inorganic salt (chemical compound) containing magnesium, sulfur and oxygen, with the formula MgSO4. It is often encountered as the heptahydrate sulfate mineral epsomite (MgSO4·7H2O), commonly called Epsom salt, taking 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. 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]

Anhydrous magnesium sulfate is used as a drying agent. The anhydrous form is hygroscopic (readily absorbs water from the air) and is therefore difficult to weigh accurately; the hydrate is often preferred when preparing solutions (for example, in medical preparations). 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. Epsom Salts are also effective in the removal of splinters. [2]

It is on the World Health Organization's List of Essential Medicines, a list of the most important medication needed in a basic health system.[3]

Uses[edit]

Medical[edit]

Magnesium sulfate is a common pharmaceutical preparation of magnesium, commonly known as Epsom salts, used both externally and internally. Epsom salts are used as bath salts. The sulfate is supplied in a gel preparation for topical application in treating aches and pains.[citation needed] Oral magnesium sulfate is commonly used as a saline laxative or osmotic purgative. Magnesium sulfate is the main preparation of intravenous magnesium.

Bathing in a 1% solution of Epsom salts (about 500g of Epsom salts for a standard size bathtub of 60 litres) is a "a safe and easy way to increase sulfate and magnesium levels in the body". [4]

Indications for internal use are:

  • Replacement therapy for hypomagnesemia.[5]
  • Magnesium sulfate is the first-line antiarrhythmic agent for torsades de pointes in cardiac arrest under the 2005 ECC guidelines and for managing quinidine-induced arrhythmias.[6]
  • As a bronchodilator after beta-agonist and anticholinergic agents have been tried, e.g. in severe exacerbations of asthma.[7] Studies conducted have revealed that magnesium sulfate can be nebulized to reduce the symptoms of acute asthma.[7] It is commonly administered via the intravenous route for the management of severe asthma attacks.
  • Magnesium sulfate can be used to treat eclampsia in pregnant women.[8]
  • Intravenous magnesium sulfate has been shown to prevent cerebral palsy in preterm babies.[9] A recent systematic review suggests that antenatal intravenous magnesium sulphate can reduce the risk of cerebral palsy and gross motor dysfunction in preterm infants by on average 30%.[10]
  • Magnesium sulfate has been used as an experimental treatment of Irukandji syndrome caused by envenomation by certain species of Irukandji jellyfish, however the efficacy of this treatment remains unproven.[11]
  • Solutions of sulfate salts such as Epsom salt may be given as first aid for barium chloride poisoning.[12]

An overdose of magnesium causes hypermagnesemia.

The use of Epsom Salts is an effective method of "drawing out" stubborn or buried slivers.[2]

Agriculture[edit]

In gardening and other agriculture, magnesium sulfate is used to correct a magnesium or sulfur deficiency in soil; magnesium is an essential element in the chlorophyll molecule, and sulfur is another important Macronutrient.[13] 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, as compared to 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.[citation needed]

Other[edit]

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 saturated with magnesium sulfate until it no longer forms clumps. The hydrated solid is then removed with filtration or decantation. Other inorganic sulfate salts such as sodium sulfate and calcium sulfate may also be used in the same way.

Magnesium sulfate is used in bath salts, particularly in flotation therapy where high concentrations raise the bath water's specific gravity, effectively making the body more buoyant. Traditionally, it is also used to prepare foot baths, intended to soothe sore feet. The reason for the inclusion of the salt is partially cosmetic: the increase in ionic strength prevents some of the temporary skin wrinkling (partial maceration) which is caused by prolonged immersion of extremities in pure water. However, magnesium sulfate can also be absorbed into the skin, reducing inflammation.[citation needed] It is naturally present in some mineral waters.[citation needed]

It may also be used as a coagulant for making tofu.[14]

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.[15]

Magnesium sulfate is used as the electrolyte to prepare copper sulfate. A magnesium sulfate solution is electrolyzed with a copper anode to form copper sulfate, magnesium hydroxide, and hydrogen:

Cu + MgSO4 + 2 H2O → H2 + CuSO4 + Mg(OH)2.[citation needed]

Magnesium sulfate is used as a brewing salt in beer production to adjust the ion content of the brewing water and enhance enzyme action in the mash or promote a desired flavor profile in the beer.

Deprecated usage[edit]

  • Magnesium sulfate was once used as a tocolytic,[16][17] but meta-analyses have failed to support it as an anti-contraction medication.[18][19] And its use for prolonged periods (more than 5 to 7 days) may result in health problems for the baby.[20]

Physical properties[edit]

Magnesium sulfate is highly soluble in water. The anhydrous form is strongly hygroscopic, and can be used as a desiccant.

Magnesium sulfate is the primary substance that causes the absorption of sound in seawater[21] (acoustic energy is converted to thermal energy). Absorption is strongly dependent on frequency: lower frequencies are less absorbed by the salt, so that the sound travels much farther in the ocean. Boric acid also contributes to absorption, but the most abundant salt in seawater, sodium chloride, has negligible sound absorption.

Hydrates[edit]

Almost all known mineralogical forms of MgSO4 occur as hydrates. Epsomite is the natural analogue of "Epsom salt". Another heptahydrate, the copper-containing mineral alpersite (Mg,Cu)SO4·7H2O,[22] 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 (5), starkeyite (4) and especially sanderite (2) — are more rarely found. Kieserite is a monohydrate and is common among evaporitic deposits. Anhydrous magnesium sulfate was reported from some burning coal dumps but never treated as a mineral.

The pH of hydrates is average 6.0 (5.5 to 6.5). Magnesium hydrates have, like copper(II) sulfate, coordinated water.[23]

Manufacturing[edit]

The heptahydrate can be prepared by neutralizing sulfuric acid with magnesium carbonate or oxide, but it is usually obtained directly from natural sources.

Anhydrous magnesium sulfate is prepared only by the dehydration of a hydrate.

Occurrence[edit]

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.

References[edit]

  1. ^ Industrial Inorganic Chemistry, Karl Heinz Büchel, Hans-Heinrich Moretto, Dietmar Werner, John Wiley & Sons, 2d edition, 2000, ISBN 9783527613335
  2. ^ a b "Quick Cures/Quack Cures: Is Epsom Worth Its Salt?". Wall Street Journal. April 9, 2012. 
  3. ^ "WHO Model List of EssentialMedicines". World Health Organization. October 2013. Retrieved 22 April 2014. 
  4. ^ "Report on Absorption of magnesium sulfate (Epsom salts) across the skin". Retrieved 2013-09-06. 
  5. ^ "Pharmaceutical Information – Magnesium Sulfate". RxMed. Retrieved 2009-07-06. 
  6. ^ "When clicking citation, it is listed under ''Other medicinal and home uses''". Disabled-world.com. 2007-01-04. Retrieved 2009-07-06. 
  7. ^ 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. PMID 16002955.
  8. ^ jab averts pregnancy danger', BBC News, 30 May 2002
  9. ^ "Epsom salt can prevent cerebral palsy: U.S. study". Reuters.com. 2008-01-31. Retrieved 2009-07-06. 
  10. ^ Doyle, L. W.; Crowther, C. A.; Middleton, P.; Marret, S. (2009). "Antenatal magnesium sulfate and neurologic outcome in preterm infants: A systematic review". Obstetrics and gynecology 113 (6): 1327–1333. doi:10.1097/AOG.0b013e3181a60495. PMID 19461430.  edit
  11. ^ Corkeron M (2003). "Magnesium infusion to treat Irukandji syndrome". Med J Aust 178 (8): 411. PMID 12697017. 
  12. ^ "BARIUM CHLORIDE DIHYDRATE 4. First Aid Measures". Jtbaker.com. Retrieved 2009-07-06. 
  13. ^ Reece, J. B., & Campbell, N. A. (2011). Campbell biology. (9th ed., p. 791). Boston: Benjamin Cummings
  14. ^ 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 
  15. ^ "Do-It-Yourself Magnesium Supplements for the Reef Aquarium". Reefkeeping. 2006. Retrieved 2008-03-14. 
  16. ^ "Magnesium sulfate for preterm labor". Webmd.com. 2007-01-19. Retrieved 2009-07-06. 
  17. ^ Lewis DF (September 2005). "Magnesium sulfate: the first-line tocolytic". Obstet. Gynecol. Clin. North Am. 32 (3): 485–500. doi:10.1016/j.ogc.2005.03.002. PMID 16125045. 
  18. ^ Simhan HN, Caritis SN (2007). "Prevention of Preterm Delivery". New England Journal of Medicine 357 (5): 477–487. doi:10.1056/NEJMra050435. PMID 17671256. 
  19. ^ Nanda, K; Grimes, DA (2006). "Magnesium sulfate tocolysis: Time to quit". Obstetrics and Gynecology 108 (4): 986–989. doi:10.1097/01.AOG.0000236445.18265.93. PMID 17012463. 
  20. ^ "Magnesium Sulfate: Drug Safety Communication - Recommendation Against Prolonged Use in Pre-term Labor". FDA. Retrieved 2 June 2013. 
  21. ^ "Underlying physics and mechanisms for the absorption of sound in seawater". Resource.npl.co.uk. Retrieved 2009-07-06. 
  22. ^ 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. 
  23. ^ Lucia Odochian "Study of the nature of the crystallization water in some magnesium hydrates by thermal methods," J. of Thermal Analysis and Calorimetry, Volume 45, Number 6, December, 1995. doi:10.1007/BF02547437

External links[edit]