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Magnesium sulfate

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Magnesium sulfate
Anhydrous magnesium sulfate
General
Systematic name Magnesium sulfate
heptahydrate
Other names Epsom salts
bitter salts
Molecular formula MgSO4·7H2O
Molar mass 120.4 g/mol
Appearance white crystalline solid
CAS number [?]
EINECS number ?
Properties
Density and phase g/cm3, solid
Solubility in water g/100 ml (0 °C)
In ethanol Slightly soluble (anh.)
Insoluble (hydrate)
Melting point °C decomp.
Structure
Coordination geometry ?
Crystal structure monoclinic (hydrate)
Safety data
PEL-TWA (OSHA)
RTECS number ?
Supplementary data page
Structure & properties n, εr, etc.
Thermodynamic data Phase behaviour
Solid, liquid, gas
Spectral data UV, IR, NMR, MS
Related compounds
Other cations Calcium sulfate
Aluminium sulfate
Related compounds
Except where noted otherwise, data are given for
materials in their standard state (at 25°C, 100 kPa)
Infobox disclaimer and references

Magnesium sulfate or Epsom salt is a chemical compound of magnesium with the formula MgSO4. It forms a heptahydrate.

Origin

Epsom salt was originally prepared by boiling down mineral waters at Epsom, England and afterwards prepared from sea water. In more recent times, these salts are obtained from certain minerals such as epsomite.

Agricultural use

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, and tomatoes. The advantage of magnesium sulfate over other magnesium soil amendments (such as dolomitic lime) is its high solubility.

Medical use

Epsom salts

Locally it may be used as a treatment of an ingrown nail. Oral magnesium sulfate, or magnesium oxide, is used as a laxative. Epsom salts are also available in a gel form for topical application in treating aches and pains. Intravenous use is broadening, as magnesium sulfate reduces striated muscle contractions and blocks peripheral neuromuscular transmission by reducing acetylcholine release at the myoneural junction, as well as other effects. Indications for its use are:

Use in organic chemistry

Anhydrous magnsium sulfate is commonly used as a drying agent in organic synthesis due to its ability to become hydrated. During workup an organic phase is saturated with the compound until it no longer forms clumps. The hydrated solid is then removed with filtration.

A number of other inorganic sulfate salts, sodium sulfate and calcium sulfate for example, may also be used in the same way.

Other uses

Magnesium sulfate is used as a bath salt, particularly in floatation 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 LavaLamps damaged by being shaken by exchanging the water and adding drops of a concentrated solution until sustainable boyency is reached. Traditionally, it is also used to prepare foot baths, intended to soothe sore feet.

See also

Reference

  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.