Iron(II) sulfate
Iron(II) sulfate when dissolved in water | |
Names | |
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IUPAC name
Iron(II) sulfate | |
Other names
Iron(II) sulphate; Ferrous sulfate, Green vitriol, Iron vitriol, Ferrous vitriol, Copperas, Melanterite, Szomolnokite, | |
Identifiers | |
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3D model (JSmol) |
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ChEBI |
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ChEMBL |
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ChemSpider | |
ECHA InfoCard | 100.028.867 |
EC Number |
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PubChem CID |
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RTECS number |
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UNII |
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UN number | 3077 |
CompTox Dashboard (EPA) |
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Properties | |
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 |
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) |
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 | |
Orthorhombic, oP24 (anhydrous) Monoclinic, mS36 (monohydrate) Monoclinic, mP72 (tetrahydrate) Triclinic, aP42 (pentahydrate) Monoclinic, mS192 (hexahydrate) Monoclinic, mP108 (heptahydrate) | |
Pnma, No. 62 (anhydrous) C2/c, No. 15 (monohydrate, hexahydrate) P21/n, No. 14 (tetrahydrate) P1, No. 2 (pentahydrate) P21/c, No. 14 (heptahydrate) | |
2/m 2/m 2/m (anhydrous) 2/m (monohydrate, tetrahydrate, hexahydrate, heptahydrate) 1 (pentahydrate) | |
a = 8.704(2) Å, b = 6.801(3) Å, c = 4.786(8) Å (293 K, anhydrous) α = 90°, β = 90°, γ = 90° | |
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 | |
B03AA07 (WHO) | |
none | |
Pharmacokinetics: | |
4 days | |
2-4 months with peak activity at 7-10 days | |
Legal status |
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Hazards | |
GHS labelling: | |
Warning | |
H302, H315, H319 | |
P305+P351+P338 | |
NFPA 704 (fire diamond) | |
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).
Infobox references |
Iron(II) sulfate (British English: iron(II) sulphate) or ferrous sulfate denotes a range of salts with the formula Fe SO4·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 sulfate), 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 2021, it was the 105th most commonly prescribed medication in the United States, with more than 6 million prescriptions.