Iron(II) sulfate

Iron(II) sulfate
Names
	IUPAC name Iron(II) sulfate
	Other names Iron(II) sulphate; Ferrous sulfate, Green vitriol, Iron vitriol, Ferrous vitriol, Copperas, Melanterite, Szomolnokite,
Identifiers
CAS Number	anhydrous: 7720-78-7 ; monohydrate: 17375-41-6 ; dihydrate: 10028-21-4 ; heptahydrate: 7782-63-0 ;
3D model (JSmol)	anhydrous: Interactive image; heptahydrate: Interactive image;
ChEBI	anhydrous: CHEBI:75832 ;
ChEMBL	anhydrous: ChEMBL1200830 ;
ChemSpider	anhydrous: 22804 ; monohydrate: 56459 ; heptahydrate: 22804 ;
ECHA InfoCard	100.028.867
EC Number	anhydrous: 231-753-5;
PubChem CID	anhydrous: 24393; monohydrate: 62712; heptahydrate: 62662;
RTECS number	anhydrous: NO8500000 (anhydrous); NO8510000 (heptahydrate);
UNII	anhydrous: 2IDP3X9OUD ; monohydrate: RIB00980VW ; dihydrate: G0Z5449449 ; heptahydrate: 39R4TAN1VT ;
UN number	3077
CompTox Dashboard (EPA)	anhydrous: DTXSID0029688 ;
	InChI InChI=1S/Fe.H2O4S/c;1-5(2,3)4/h;(H2,1,2,3,4)/q+2;/p-2 Key: BAUYGSIQEAFULO-UHFFFAOYSA-L ; anhydrous: InChI=1/Fe.H2O4S/c;1-5(2,3)4/h;(H2,1,2,3,4)/q+2;/p-2 Key: BAUYGSIQEAFULO-NUQVWONBAS;
	SMILES anhydrous: [Fe+2].[O-]S([O-])(=O)=O; heptahydrate: [OH2+][Fe-4]([OH2+])([OH2+])([OH2+])([OH2+])[OH2+].[O-]S(=O)(=O)[O-].O;
Properties
Chemical formula	FeSO4
Molar mass	151.91 g/mol (anhydrous); 169.93 g/mol (monohydrate); 241.99 g/mol (pentahydrate); 260.00 g/mol (hexahydrate); 278.02 g/mol (heptahydrate)
Appearance	White crystals (anhydrous); White-yellow crystals (monohydrate); Blue-green deliquescent crystals (heptahydrate)
Odor	Odorless
Density	3.65 g/cm3 (anhydrous); 3 g/cm3 (monohydrate); 2.15 g/cm3 (pentahydrate); 1.934 g/cm3 (hexahydrate); 1.895 g/cm3 (heptahydrate)
Melting point	680 °C (1,256 °F; 953 K) ; (anhydrous) decomposes; 300 °C (572 °F; 573 K); (monohydrate) decomposes; 60–64 °C (140–147 °F; 333–337 K); (heptahydrate) decomposes
Solubility in water	Monohydrate:; 44.69 g/100 mL (77 °C); 35.97 g/100 mL (90.1 °C); Heptahydrate:; 15.65 g/100 mL (0 °C); 19.986 g/100 mL (10 °C); 29.51 g/100 mL (25 °C); 39.89 g/100 mL (40.1 °C); 51.35 g/100 mL (54 °C)
Solubility	Negligible in alcohol
Solubility in ethylene glycol	6.38 g/100 g (20 °C)
Vapor pressure	1.95 kPa (heptahydrate)
Magnetic susceptibility (χ)	1.24×10−2 cm3/mol (anhydrous); 1.05×10−2 cm3/mol (monohydrate); 1.12×10−2 cm3/mol (heptahydrate); +10200×10−6 cm3/mol
Refractive index (nD)	1.591 (monohydrate); 1.526–1.528 (21 °C, tetrahydrate); 1.513–1.515 (pentahydrate); 1.468 (hexahydrate); 1.471 (heptahydrate)
Structure
Crystal structure	Orthorhombic, oP24 (anhydrous); Monoclinic, mS36 (monohydrate); Monoclinic, mP72 (tetrahydrate); Triclinic, aP42 (pentahydrate); Monoclinic, mS192 (hexahydrate); Monoclinic, mP108 (heptahydrate)
Space group	Pnma, No. 62 (anhydrous); C2/c, No. 15 (monohydrate, hexahydrate); P21/n, No. 14 (tetrahydrate); P1, No. 2 (pentahydrate); P21/c, No. 14 (heptahydrate)
Point group	2/m 2/m 2/m (anhydrous); 2/m (monohydrate, tetrahydrate, hexahydrate, heptahydrate); 1 (pentahydrate)
Lattice constant	a = 8.704(2) Å, b = 6.801(3) Å, c = 4.786(8) Å (293 K, anhydrous) α = 90°, β = 90°, γ = 90°
Coordination geometry	Octahedral (Fe2+)
Thermochemistry
Heat capacity (C)	100.6 J/mol·K (anhydrous); 394.5 J/mol·K (heptahydrate)
Std molar; entropy (S⦵298)	107.5 J/mol·K (anhydrous); 409.1 J/mol·K (heptahydrate)
Std enthalpy of; formation (ΔfH⦵298)	−928.4 kJ/mol (anhydrous); −3016 kJ/mol (heptahydrate)
Gibbs free energy (ΔfG⦵)	−820.8 kJ/mol (anhydrous); −2512 kJ/mol (heptahydrate)
Pharmacology
ATC code	B03AA07 (WHO)
Dependence liability	none
	Pharmacokinetics:
Onset of action	4 days
Duration of action	2-4 months with peak activity at 7-10 days
Legal status	US: OTC;
Hazards
	GHS labelling:
Pictograms
Signal word	Warning
Hazard statements	H302, H315, H319
Precautionary statements	P305+P351+P338
NFPA 704 (fire diamond)	1 0 0
	Lethal dose or concentration (LD, LC):
LD50 (median dose)	237 mg/kg (rat, oral)
	NIOSH (US health exposure limits):
REL (Recommended)	TWA 1 mg/m3
Related compounds
Other cations	Cobalt(II) sulfate; Copper(II) sulfate; Manganese(II) sulfate; Nickel(II) sulfate
Related compounds	Iron(III) 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

Iron(II) sulfate or ferrous sulfate (British English: sulphate instead of sulfate) denotes a range of salts with the formula FeSO₄·xH₂O. These compounds exist most commonly as the heptahydrate (x = 7), but several values for x are known. The hydrated form is used medically to treat or prevent iron deficiency, and also for industrial applications. Known since ancient times as copperas and as green vitriol (vitriol is an archaic name for hydrated sulfate minerals), the blue-green heptahydrate (hydrate with 7 molecules of water) is the most common form of this material. All the iron(II) sulfates dissolve in water to give the same aquo complex [Fe(H₂O)₆]²⁺, which has octahedral molecular geometry and is paramagnetic. The name copperas dates from times when the copper(II) sulfate was known as blue copperas, and perhaps in analogy, iron(II) and zinc sulfate were known respectively as green and white copperas.

It is on the World Health Organization's List of Essential Medicines. In 2022, it was the 107th most commonly prescribed medication in the United States, with more than 6 million prescriptions.