Magnesium-sulfate.jpg Magnesium-sulfate.jpg

Magnesium sulfate (1:1)

CAS Registry Number (CASRN):

۷۴۸۷-۸۸-۹ ,

Units of original limits:

mg/m3 ,

Conc dep:

N ,


Magnesium sulfate (1:1) ,


MgSO4 ,

CAS Registry Number (CASRN):

۷۴۸۷-۸۸-۹ ,

SAX Number:

ML30MJ2U7I ,

Units of original limits:

mg/m3 ,

Conc dep:

N ,

p to m:

4.91969 ,


3 ,

specific gravity:

2.66 ,

state at 25 °C:

S ,

Molar mass (g/mol):

120.366 ,

Density (g/cm3):

2.66 ,

Melting point (°C):

1124 ,

solubility in water (g/100g):

269 ,


Magnesium sulfate

Magnesium sulfate 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.

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: for example, Epsom salt is also effective in the removal of splinters.[2]

It is on the WHO Model List of Essential Medicines, the most important medications needed in a basic health system


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. Other inorganic sulfate salts such as sodium sulfate and calcium sulfate may also be used in the same way.

Marine use

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.

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