Magnesium sulfate

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Magnesium sulfate
Anhydrous magnesium sulfate
IUPAC name
Other names Epsom salt
Bitter salts
Identifiers
CAS number [7487-88-9],
14168-73-1 (monohydrate)
24378-31-2 (tetrahydrate)
15553-21-6 (pentahydrate)
13778-97-7 (hexahydrate)
10034-99-8 (heptahydrate)
PubChem 24083
RTECS number OM4500000
ChemSpider ID 22515
Properties
Molecular formula MgSO4
Molar mass 120.415 g/mol (anhydrous)
246.47 g/mol (heptahydrate)
Appearance white crystalline solid
Density 2.66 g/cm3 (anhydrous)
2.445 g/cm3 (monohydrate)
1.68 g/cm3 (heptahydrate)
Melting point

1124 °C (anhydrous, decomp)
200 °C (monohydrate, decomp)
150 °C (heptahydrate, decomp)
Solubility in water anhydrous
26.9 g/100 mL (0 °C)
25.5 g/100 mL (20 °C)
heptahydrate
71 g/100 mL (20 °C)
Solubility .0116 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
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, 100 kPa)
Infobox references

Magnesium sulfate (or magnesium sulphate) is a chemical compound containing magnesium and sulfur, with the formula MgSO4. In its hydrated form the pH is 6.0 (5.5 to 6.5). It is often encountered as the heptahydrate, MgSO4·7H2O, commonly called Epsom salt. Anhydrous magnesium sulfate is used as a drying agent. Since the anhydrous form is hygroscopic (readily absorbs water from the air) and therefore harder 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.

Contents

[edit] Properties

Magnesium sulfate is the primary substance that causes the absorption of sound in seawater.[1] Absorption, in this case, means the conversion of acoustic energy to heat energy. The conversion is a strong function of frequency. Lower frequencies are less affected by the salt, so that the acoustic energy travels much farther in the ocean. Boric acid also contributes to absorption, but much less than MgSO4, and the most common salt, sodium chloride, has no effect on sound absorption.

[edit] Occurrence

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. Almost all known mineralogical forms of MgSO4 occur as hydrates. Epsomite is the natural analogue of "Epsom salt," mentioned above. Another heptahydrate, the copper-containing mineral alpersite (Mg,Cu)SO4·7H2O, was also 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.It is obtained by treating magnesium oxide with sulphur dioxide

[edit] Applications

In agriculture and gardening, magnesium sulfate is used to correct magnesium deficiency in soil (magnesium is an essential element in the chlorophyll molecule). It is most commonly applied to potted plants, or to magnesium-hungry crops, such as potatoes, roses, tomatoes, peppers and cannabis. The advantage of magnesium sulfate over other magnesium soil amendments (such as dolomitic lime) is its high solubility.

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. This property is also used to restore some Lava lamps damaged by being shaken by exchanging the water and adding drops of a concentrated solution until sustainable buoyancy is reached. 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 ("pruning" -- 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. It is also sometimes found in bottled mineral water, and accordingly is sometimes listed in the contents thereof. It may also be used as a coagulant for making tofu.[2]

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.[3] It is also recommended for dropsy treatment for fish.[4]

An old remedy for diarrhea in adult chickens is 1/2 tsp per bird per day added to their feed.[5]

[edit] Medical use

Further information: Hypomagnesemia

Oral magnesium sulfate, or magnesium hydroxide, is commonly used as a saline laxative. Epsom salt is also available in a gel form for topical application in treating aches and pains.

Indications for its use are

  • Replacement therapy for hypomagnesemia.[6]
  • 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.[7]
  • As a bronchodilator after beta-agonist and anticholinergic agents have been tried, e.g. in severe exacerbations of asthma.[8] Recent studies have revealed that magnesium sulfate can be nebulized to reduce the symptoms of acute asthma.[8] It is commonly administered via the intravenous route for the management of severe asthma attacks.
  • Users of Epsom salt in the gel form have reported significant and lasting reduction of pain associated with fibromyalgia and osteoporosis.[9]
  • A 2004 research study showed that both magnesium and sulfate are absorbed through the skin when bathing in 1% solution.[10]
  • Magnesium sulfate can be used to treat eclampsia in pregnant women.[11]
  • Magnesium sulfate can also delay labor in the case of premature labor, to delay preterm birth.[12]
  • Intravenous magnesium sulfate may be able to prevent cerebral palsy in preterm babies.[13]
  • Solutions of sulfate salts such as Epsom salt may be given as first aid for barium chloride poisoning.[14]
  • Magnesium sulfate paste has been used as an agent for dehydrating (drawing) boils, carbuncles, and abscesses.[15]
  • Magnesium sulfate solution has also been shown to be an effective aid in the fight against blemishes and acne when applied directly to problematic areas, usually in poultice form.[16] If combined with water and made into a cream, it can be applied to the face to remove blackheads.
  • Magnesium sulfate, when used through soaking, can soothe muscle pains and help improve rough patches in the skin.[17]
  • The body's magnesium level increases when soaking with magnesium sulfate, which is necessary for serotonin, a mood-regulating neurotransmitter that may increase feelings of relaxation and well-being.[18]
  • Soaking in a warm bath containing Epsom salt (magnesium sulfate) can be beneficial to soothe and relieve herpes outbreak symptoms, such as itching and lesions relating to genital herpes and shingles.[19][20]

[edit] References

  1. ^ "Underlying physics and mechanisms for the absorption of sound in seawater". Resource.npl.co.uk. http://resource.npl.co.uk/acoustics/techguides/seaabsorption/physics.html. Retrieved on 2009-07-06. 
  2. ^ "Process for producing packed tofu". http://www.freepatentsonline.com/6042851.html. 
  3. ^ "Do-It-Yourself Magnesium Supplements for the Reef Aquarium". Reefkeeping. 2006. http://reefkeeping.com/issues/2006-07/rhf/index.php. Retrieved on 2008-03-14. 
  4. ^ "Dropsy". www.healthybetta.com. 2004. http://www.healthybetta.com/articles/Illness%20Diagonsis/dropsy.html. Retrieved on 2007-05-20. 
  5. ^ "Old Time Remedies for Common Poultry Diseases". Mother Earth News. March 1974. http://www.motherearthnews.com/Sustainable-Farming/1974-03-01/Old-Time-Remedies.aspx. Retrieved on 2008-03-05. 
  6. ^ "Pharmaceutical Information - MAGNESIUM SULFATE". RxMed. http://www.rxmed.com/b.main/b2.pharmaceutical/b2.1.monographs/CPS-%20Monographs/CPS-%20(General%20Monographs-%20M)/MAGNESIUM%20SULFATE.html. Retrieved on 2009-07-06. 
  7. ^ "When clicking citation, it is listed under ''Other medicinal and home uses''". Disabled-world.com. 2007-01-04. http://www.disabled-world.com/artman/publish/epsom-salts.shtml. Retrieved on 2009-07-06. 
  8. ^ 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.
  9. ^ "Fibromyalgia Forum - epsom salt and fibromyalgia??". Ehealthforum.com. http://ehealthforum.com/health/epsom-salt-and-fibromyalgia-t157934.html. Retrieved on 2009-07-06. 
  10. ^ Rosemary Waring Absorption of magnesium sulphate through the skin (republished by the Epsom Salt Council), 2004
  11. ^ BBC News story 'Simple jab averts pregnancy danger' [1] 30 May 2002
  12. ^ "Magnesium sulfate for preterm labor". Webmd.com. 2007-01-19. http://www.webmd.com/baby/magnesium-sulfate-for-preterm-labor. Retrieved on 2009-07-06. 
  13. ^ "Epsom salt can prevent cerebral palsy: U.S. study". Reuters.com. 2008-01-31. http://www.reuters.com/article/healthNews/idUSHUN17633820080131?sp=true. Retrieved on 2009-07-06. 
  14. ^ "When clicking citation, it is ''Number 4'' on the list". Jtbaker.com. http://www.jtbaker.com/msds/englishhtml/b0372.htm. Retrieved on 2009-07-06. 
  15. ^ "How to Get Rid of Boils". Getridofthings.com. http://www.getridofthings.com/get-rid-of-boils.htm. Retrieved on 2009-07-06. 
  16. ^ "Acne guide". Frihost.com. http://www.frihost.com/forums/vt-51486.html. Retrieved on 2009-07-06. 
  17. ^ "When clicking citation, it is ''Number 10''". Articlesbase.com. 2009-01-31. http://www.articlesbase.com/diseases-and-conditions-articles/10-tips-to-reduce-muscle-pain-naturally-without-side-effects-749262.html. Retrieved on 2009-07-06. 
  18. ^ "Epsom Salt Industry Council - About Epsom Salt - The Science of Epsom Salt" Epsom Salt Council
  19. ^ "Herpes Home Remedies" Herpes and Cold Sores Support Network
  20. ^ "McKinley Health Center - Genital Herpes - University of Illinois" McKinley Health Center, University of Illinois
v • d • e
Antiarrhythmic agents (C01B)
Channel blockers
class Ia (Phase 0→ and Phase 3→)
class Ib (Phase 3←)
class Ic (Phase 0→)
Receptor agonists
and antagonists
Propranolol • Nadolol • Pindolol • cardioselective (Atenolol, Metoprolol, Acebutolol, Esmolol)
Ion transporters
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