Iron(II) sulfate (British English: iron(II) sulphate) or ferrous
sulfate denotes a range of salts with the formula FeSO4·xH2O. These
compounds exist most commonly as the heptahydrate (x = 7)
but are known for several values of x. The hydrated form is used
medically to treat iron deficiency, and also for industrial
applications. Known since ancient times as copperas and as green
vitriol, the blue-green heptahydrate 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
It is on the World Health Organization's List of Essential Medicines,
the most important medications needed in a basic health system.
1.1 Medical use
1.3 Other uses
3 Production and reactions
4 See also
6 External links
Industrially, ferrous sulfate is mainly used as a precursor to other
iron compounds. It is a reducing agent, and as such is useful for the
reduction of chromate in cement to less toxic Cr(III) compounds.
Historically ferrous sulfate was used in the textile industry for
centuries as a dye fixative. It is used historically to blacken
leather and as a constituent of ink. The preparation of sulfuric
acid ('oil of vitriol') by the distillation of green vitriol (Iron(II)
sulfate) has been known for at least 700 years.
Together with other iron compounds, ferrous sulfate is used to fortify
foods and to treat and prevent iron deficiency anemia. Constipation is
a frequent and uncomfortable side effect associated with the
administration of oral iron supplements. Stool softeners often are
prescribed to prevent constipation.
Ferrous sulfate was used in the manufacture of inks, most notably iron
gall ink, which was used from the middle ages until the end of the
eighteenth century. Chemical tests made on the Lachish letters
(c.588–586 BCE) showed the possible presence of iron. It is
thought that oak galls and copperas may have been used in making the
ink on those letters. It also finds use in wool dyeing as a
mordant. Harewood, a material used in marquetry and parquetry since
the 17th century, is also made using ferrous sulfate.
Two different methods for the direct application of indigo dye were
developed in England in the eighteenth century and remained in use
well into the nineteenth century. One of these, known as china blue,
involved iron(II) sulfate. After printing an insoluble form of indigo
onto the fabric, the indigo was reduced to leuco-indigo in a sequence
of baths of ferrous sulfate (with reoxidation to indigo in air between
immersions). The china blue process could make sharp designs, but it
could not produce the dark hues of other methods. Sometimes, it is
included in canned black olives as an artificial colorant.
Ferrous sulfate can also be used to stain concrete and some limestones
and sandstones a yellowish rust color.
Woodworkers use ferrous sulfate solutions to color maple wood a
In horticulture it is used for treating iron chlorosis. Although
not as rapid-acting as ferric edta, its effects are longer-lasting. It
can be mixed with compost and dug into the soil to create a store
which can last for years. It is also used as a lawn
conditioner, and moss killer.
In the second half of the 1850s ferrous sulfate was used as a
photographic developer for collodion process images.
Ferrous sulfate is sometimes added to the cooling water flowing
through the brass tubes of turbine condensers to form a
corrosion-resistant protective coating.
It is used in gold refining to precipitate metallic gold from auric
chloride solutions (gold dissolved in solution with aqua regia).
It has been used in the purification of water by flocculation and for
phosphate removal in municipal and industrial sewage treatment plants
to prevent eutrophication of surface water bodies.
It is used as a traditional method of treating wood
panelling[clarification needed] on houses, either alone, dissolved in
water, or as a component of water-based paint.
Green vitriol is also a useful reagent in the identification of
Iron(II) sulfate can be found in various states of hydration, and
several of these forms exist in nature.
FeSO4·H2O (mineral: Szomolnokite, relatively rare)
FeSO4·4H2O (mineral: Rozenite, white, relatively common, may be
dehydratation product of melanterite)
FeSO4·5H2O (mineral: Siderotil, relatively rare)
FeSO4·6H2O (mineral: Ferrohexahydrite, relatively rare)
FeSO4·7H2O (mineral: Melanterite, blue-green, relatively common)
Anhydrous iron(II) sulfate
The tetrahydrate is stabilized when the temperature of aqueous
solutions reaches 56.6 °C (133.9 °F). At 64.8 °C
(148.6 °F) these solutions form both the tetrahydrate and
All mentioned mineral forms are connected with oxidation zones of
iron-bearing ore beds (pyrite, marcasite, chalcopyrite, etc.) and
related environments (like coal fire sites). Many undergo rapid
dehydration and sometimes oxidation.
Production and reactions
In the finishing of steel prior to plating or coating, the steel sheet
or rod is passed through pickling baths of sulfuric acid. This
treatment produces large quantities of iron(II) sulfate as a
Fe + H2SO4 → FeSO4 + H2
Another source of large amounts results from the production of
titanium dioxide from ilmenite via the sulfate process.
Ferrous sulfate is also prepared commercially by oxidation of pyrite:
2 FeS2 + 7 O2 + 2 H2O → 2 FeSO4 + 2 H2SO4
Upon dissolving in water, ferrous sulfates form the metal aquo complex
[Fe(H2O)6]2+, which is an almost colorless, paramagnetic ion.
On heating, iron(II) sulfate first loses its water of crystallization
and the original green crystals are converted into a brown colored
anhydrous solid. When further heated, the anhydrous material releases
sulfur dioxide and white fumes of sulfur trioxide, leaving a
reddish-brown iron(III) oxide. Decomposition of iron(II) sulfate
begins at about 680 °C (1,256 °F).
2 FeSO4 → Fe2O3 + SO2 + SO3
Like all iron(II) salts, iron(II) sulfate is a reducing agent. For
example, it reduces nitric acid to nitrogen monoxide and chlorine to
6 FeSO4 + 3 H2SO4 + 2 HNO3 → 3 Fe2(SO4)3 +
4 H2O + 2 NO
6 FeSO4 + 3 Cl2 → 2 Fe2(SO4)3 + 2 FeCl3
Iron(II) sulfate outside a titanium dioxide factory in Kaanaa, Pori,
Upon exposure to air, it oxidizes to form a corrosive brown-yellow
coating of "basic ferric sulfate", which is an adduct of iron(III)
oxide and iron(III) sulfate:
12 FeSO4 + 3 O2 → 4 Fe2(SO4)3 + 2 Fe2O3
Iron(III) sulfate (ferric sulfate), the other common simple sulfate of
Ammonium iron(II) sulfate, also known as Mohr's salt, the common
double salt of ammonium sulfate with iron(II) sulfate.
Ephraim Seehl known as an early manufacturer of green vitriol.
^ a b c d e f "
Siderotil Mineral Data". Retrieved 2014-08-03.
^ a b c d e f "Ferrohexahydrite Mineral Data". Retrieved
^ a b c d e f g h Lide, David R., ed. (2009). CRC Handbook of
Chemistry and Physics (90th ed.). Boca Raton, Florida: CRC Press.
^ a b Seidell, Atherton; Linke, William F. (1919). Solubilities of
Inorganic and Organic Compounds (2nd ed.). New York: D. Van Nostrand
Company. p. 343.
^ a b Anatolievich, Kiper Ruslan. "iron(II) sulfate". Retrieved
^ a b c d
Iron(II) sulfate heptahydrate. Retrieved
^ a b c d e Ralph, Jolyon; Chautitle, Ida. "Szomolnokite". Mindat.org.
^ a b c d e "
Rozenite Mineral Data". Retrieved 2014-08-03.
^ a b c d e "
Melanterite Mineral Data". Retrieved 2014-08-03.
^ a b c "MSDS of Ferrous sulfate heptahydrate". Fair Lawn, New Jersey:
Fisher Scientific, Inc. Retrieved 2014-08-03.
^ a b c d Weil, Matthias (2007). "The High-temperature β Modification
of Iron(II) Sulfate". Acta Crystallographica Section E. International
Union of Crystallography. 63 (12): i192.
doi:10.1107/S160053680705475X. Retrieved 2014-08-03.
^ a b c d Anatolievich, Kiper Ruslan. "iron(II) sulfate heptahydrate".
^ "NIOSH Pocket Guide to Chemical Hazards #0346". National Institute
for Occupational Safety and Health (NIOSH).
^ Brown, Lesley (1993). The New shorter Oxford English dictionary on
historical principles. Oxford [Eng.]: Clarendon.
^ "WHO Model List of Essential Medicines (19th List)" (PDF). World
Health Organization. April 2015. Retrieved 8 December 2016.
^ British Archeology magazine.
^ Torczyner, Lachish Letters, pp. 188–95
^ Hyatt, The Interpreter's Bible, 1951, volume V, p. 1067
^ How To Stain Concrete with
^ Koenig, Rich and Kuhns, Mike: Control of
Ornamental and Crop Plants. (Utah State University, Salt Lake City,
August 1996) p.3
^ a b Handreck, Kevin (2002). Gardening Down Under: A Guide to
Healthier Soils and Plants (2nd ed.). Collingwood, Victoria: CSIRO
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^ Svrček, Mirko (1975). A color guide to familiar mushrooms (2nd
ed.). London: Octopus Books. p. 30.
^ Wildermuth, Egon; Stark, Hans; Friedrich, Gabriele; Ebenhöch, Franz
Ludwig; Kühborth, Brigitte; Silver, Jack; Rituper, Rafael (2005),
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^ Pryce, William (1778). Mineralogia Cornubiensis; a Treatise on
Minerals, Mines and Mining. London: Phillips. p. 33.
Wikimedia Commons has media related to Iron(II) sulfate.
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Hunt, T. Sterry (1879). "Copperas". The American
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