Iron(II) sulfate
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Iron(II) sulfate | |
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Systematic name | Iron(II) sulfate |
Other names | ferrous sulfate green vitriol copperas melanterite szomolnokite |
Molecular formula | FeSO4·H2O FeSO4·4H2O FeSO4·5H2O FeSO4·7H2O |
Molar mass | 151.908g/mol |
CAS number | [7720-78-7] |
Appearance | blue/green or white crystals |
Crystal structure | monoclinic |
Density | ? |
Solubility (water) | Soluble |
Melting point | 64°C |
Boiling point | 90°C (becomes FeSO4·H2O) |
Disclaimer and references |
Iron(II) sulfate (IUPAC-recommended spelling; also sulphate in British English), also known as ferrous sulfate (FeSO4) is an ionic compound.
Iron(II) sulfate can be found in various states of hydration:
- FeSO4·H2O
- FeSO4·4H2O
- FeSO4·5H2O
- FeSO4·7H2O
The heptahydrate is also called green vitriol, copperas, or melanterite (a mineral that commonly occurs with pyrite).
Iron(II) sulfate has a blue-green color, monoclinic crystal structure, and is water-soluble. Its molecular weight is 151.9026 g/mol. Its melting point is 64°C, and at 90°C it loses water of hydration to form the monohydrate, a white powder known as the mineral szomolnokite when it occurs naturally. Iron sulfate pentahydrate forms the mineral siderotil.
Iron(II) sulfate is prepared commercially by oxidation of pyrite or by treating iron with sulfuric acid. It is used in the manufacture of inks, most notably Iron gall ink, which was commonly used during the time of the American Revolution, in wool dyeing as a mordant, and in water purification as a substitute for aluminium sulfate.
In the finishing of steel prior to plating or coating, the steel sheet or rod is passed through pickling lines of sulfuric acid. This produces large quantities of iron(II) sulfate as a waste product.
In horticulture it is used as a lawn conditioner and moss killer, traditionally referred to as sulphate of iron.
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[edit] Medicinal uses
Ferrous sulfate is also used to treat iron-deficiency anemia. Side effects of therapy may include nausea and epigastric abdominal discomfort after taking iron. These side effects can be minimized by taking ferrous sulfate at bedtime.
[edit] Decorative Uses
Ferrous sulfate can also be used to color concrete. It is best used for newly cured concrete. Mix with water until saturated and spray onto concrete. The color will range from yellow to rust.
[edit] Historical uses
Two different methods for the direct application of indigo 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 the insoluble form of indigo onto the fabric, the indigo was oxidized in a sequence of baths of ferrous sulfate. The china blue process could make sharp designs, but it could not produce the dark hues.
Ferrous sulfate (then known as green vitriol) was also much used in the middle ages to make Iron-gall nut ink for use in writing.