Magnesium sulfate
Magnesium sulfate | |
---|---|
Anhydrous magnesium sulfate | |
Magnesium sulfate | |
Other names Epsom salt Bitter salts | |
style="background: #F8EABA; text-align: center;" colspan="2" | 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 |
ChemSpider | 22515 |
RTECS number | OM4500000 |
style="background: #F8EABA; text-align: center;" colspan="2" | Properties | |
Molecular formula | MgSO4 |
Molar mass | 120.366 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) |
Solubility in water | anhydrous 269 g/L (0 °C) 255 g/L (20 °C) heptahydrate 710 g/L (20 °C) |
Solubility | 0.116 g/L (18 °C, ether) slightly soluble in alcohol, glycerol insoluble in acetone |
Refractive index (nD) | 1.523 (monohydrate) 1.433 (heptahydrate) |
style="background: #F8EABA; text-align: center;" colspan="2" | Structure | |
Crystal structure | monoclinic (hydrate) |
style="background: #F8EABA; text-align: center;" colspan="2" | Hazards | |
MSDS | External MSDS |
EU Index | Not listed |
style="background: #F8EABA; text-align: center;" colspan="2" | Related compounds | |
Other cations | Beryllium sulfate Calcium sulfate Strontium sulfate Barium sulfate |
(what is this?) (verify) 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, sulfur and oxygen, with the formula MgSO4. It is often encountered as the heptahydrate epsomite (MgSO4·7H2O), commonly called "Epsom salt". Another hydrate form is kieserite.
Anhydrous magnesium sulfate is used as a drying agent. Since 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.
Contents
[hide]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 the most abundant salt in seawater, sodium chloride, has no known effect on sound absorption.
Hydrates
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[2], 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.
The pH of hydrates is average 6.0 (5.5 to 6.5). Magnesium hydrates have, like Copper(II) sulfate, coordinated water. [3]
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.
Applications
In agriculture and gardening, magnesium sulfate is used to correct magnesium deficiency in soil, since 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.[4]
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.[5]
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
Medical use
Oral magnesium sulfate 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 internal 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.
- A 2004 research study showed that both magnesium and sulfate are absorbed through the skin when bathing in 1% w/v solution.[9]
- Magnesium sulfate can be used to treat eclampsia in pregnant women.[10]
- Magnesium sulfate can also delay labor in the case of premature labor, to delay preterm birth.[11][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]
Indications for topical use are
- 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.
- Soaking in a warm bath containing Epsom salt (magnesium sulfate) can be beneficial to soothe, relax,and relieve herpes outbreak symptoms, such as itching and lesions relating to genital herpes and shingles.[17][18]
See also
References
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de:Magnesiumsulfat et:Magneesiumsulfaat es:Sulfato de magnesio fr:Sulfate de magnésium it:Solfato di magnesio he:מגנזיום גופרתי hu:Magnézium-szulfát nl:Magnesiumsulfaat ja:硫酸マグネシウム no:Magnesiumsulfat pl:Siarczan magnezu pt:Sulfato de magnésio ro:Sulfat de magneziu ru:Сульфат магния (лекарственное средство) ru:Гептагидрат сульфата магния sl:Projekt:Magnezijev sulfat sr:Магнезијум сулфат fi:Magnesiumsulfaatti sv:Magnesiumsulfat th:แมกนีเซียมซัลเฟต
zh:硫酸镁- Jump up ↑ "Underlying physics and mechanisms for the absorption of sound in seawater". Resource.npl.co.uk. Retrieved 2009-07-06.
- Jump up ↑ Lua error in package.lua at line 80: module 'Module:Citation/CS1/Suggestions' not found.
- Jump up ↑ 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
- Jump up ↑ "Process for producing packed tofu".
- Jump up ↑ "Do-It-Yourself Magnesium Supplements for the Reef Aquarium". Reefkeeping. 2006. Retrieved 2008-03-14.
- Jump up ↑ "Pharmaceutical Information - MAGNESIUM SULFATE". RxMed. Retrieved 2009-07-06.
- Jump up ↑ "When clicking citation, it is listed under ''Other medicinal and home uses''". Disabled-world.com. 2007-01-04. Retrieved 2009-07-06.
- ↑ Jump up to: 8.0 8.1 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.
- Jump up ↑ Rosemary Waring Absorption of magnesium sulphate through the skin (republished by the Epsom Salt Council), 2004
- Jump up ↑ jab averts pregnancy danger', BBC News, 30 May 2002
- Jump up ↑ "Magnesium sulfate for preterm labor". Webmd.com. 2007-01-19. Retrieved 2009-07-06.
- Jump up ↑ Lua error in package.lua at line 80: module 'Module:Citation/CS1/Suggestions' not found.
- Jump up ↑ "Epsom salt can prevent cerebral palsy: U.S. study". Reuters.com. 2008-01-31. Retrieved 2009-07-06.
- Jump up ↑ "BARIUM CHLORIDE DIHYDRATE 4. First Aid Measures". Jtbaker.com. Retrieved 2009-07-06.
- Jump up ↑ "How to Get Rid of Boils". Getridofthings.com. Retrieved 2009-07-06.
- Jump up ↑ "Acne guide". Frihost.com. Retrieved 2009-07-06.
- Jump up ↑ "Herpes Home Remedies" Herpes and Cold Sores Support Network
- Jump up ↑ "McKinley Health Center - Genital Herpes - University of Illinois" McKinley Health Center, University of Illinois