Magnesium sulfate

Magnesium sulfate
	Magnesium sulfate hexahydrate
	Anhydrous magnesium sulfate
	Epsomite (Magnesium sulfate heptahydrate)
Names
	IUPAC name Magnesium sulfate
	Other names Epsom salt (Magnesium sulfate heptahydrate); English salt; Bitter salts; Bath salt;
Identifiers
CAS Number	7487-88-9 (anhydrous) ; 14168-73-1 (monohydrate) ; 10034-99-8 (heptahydrate) ;
3D model (JSmol)	anhydrate: Interactive image; hexahydrate: Interactive image;
ChEBI	CHEBI:32599 ; CHEBI:31795 (heptahydrate);
ChEMBL	ChEMBL2021423 ; ChEMBL3989857 (heptahydrate);
ChemSpider	22515 ;
DrugBank	DB00653 ;
ECHA InfoCard	100.028.453
EC Number	231-298-2;
KEGG	C12505 (heptahydrate);
PubChem CID	24083;
RTECS number	OM4500000;
UNII	ML30MJ2U7I ; E2L2TK027P (monohydrate) ; SK47B8698T (heptahydrate) ;
CompTox Dashboard (EPA)	DTXSID6042105 ;
	InChI InChI=1S/Mg.H2O4S/c;1-5(2,3)4/h;(H2,1,2,3,4)/q+2;/p-2 Key: CSNNHWWHGAXBCP-UHFFFAOYSA-L ; InChI=1/Mg.8H2O4S/c;1-5(2,3)4/h;(H2,1,2,3,4)/q+2;/p-2 Key: CSNNHWWHGAXBCP-NUQVWONBAQ;
	SMILES anhydrate: [Mg+2].[O-]S([O-])(=O)=O; hexahydrate: [OH2+][Mg-4]([OH2+])([OH2+])([OH2+])([OH2+])[OH2+].[O-]S(=O)(=O)[O-];
Properties
Chemical formula	MgSO4
Molar mass	120.366 g/mol (anhydrous); 138.38 g/mol (monohydrate); 174.41 g/mol (trihydrate); 210.44 g/mol (pentahydrate); 228.46 g/mol (hexahydrate); 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 (undecahydrate);
Melting point	decomposes; 1,124 °C (2,055 °F) (anhydrous); 200 °C (392 °F) (monohydrate); 150 °C (302 °F) (heptahydrate); 2 °C (36 °F) (undecahydrate);
Solubility in water	anhydrous; 26.9 g/100 mL @ 0 °C (32 °F); 35.1 g/100 mL @ 20 °C (68 °F); 50.2 g/100 mL @ 100 °C (212 °F); ; heptahydrate; 113 g/100 mL @ 20 °C (68 °F);
Solubility product (Ksp)	738 (502 g/L)
Solubility in diethyl ether	1.16 g/100 mL @ 18 °C (64 °F)
Solubility in ethanol	slight
Solubility in glycerol	slight
Magnetic susceptibility (χ)	−50×10−6 cm3/mol
Refractive index (nD)	1.523 (monohydrate); 1.433 (heptahydrate);
Structure
Crystal structure	monoclinic (hydrate)
Pharmacology
ATC code	A06AD04 (WHO) A12CC02 (WHO) B05XA05 (WHO) D11AX05 (WHO) V04CC02 (WHO)
Related compounds
Other cations	Beryllium sulfate; Calcium sulfate; Strontium sulfate; Barium sulfate; Iron(II) sulfate; Copper(II) sulfate;
	Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). verify (what is ?) Infobox references

Magnesium sulfate or magnesium sulphate is a chemical compound, a salt with the formula MgSO₄, consisting of magnesium cations Mg²⁺ (20.19% by mass) and sulfate anions SO2−4. It is a white crystalline solid, soluble in water.

Magnesium sulfate is usually encountered in the form of a hydrate MgSO₄·nH₂O, for various values of n between 1 and 11. The most common is the heptahydrate MgSO₄·7H₂O, known as Epsom salt, which is a household chemical with many traditional uses, including bath salts.

The main use of magnesium sulfate is in agriculture, to correct soils deficient in magnesium (an essential plant nutrient because of the role of magnesium in chlorophyll and photosynthesis). The monohydrate is favored for this use; by the mid 1970s, its production was 2.3 million tons per year with production increasing to approximately 2.6 million tons in 2024. The anhydrous form and several hydrates occur in nature as minerals, and the salt is a significant component of the water from some springs.