Iron(II) carbonate
iron(II) carbonate, or ferrous carbonate, is a chemical compound with formula FeCO
3, that occurs naturally as the mineral siderite. At ordinary ambient temperatures, it is a green-brown ionic solid consisting of iron(II) cations Fe2+
and carbonate anions CO2−
3.[4]
| Names | |
|---|---|
| Other names
ferrous carbonate | |
| Identifiers | |
3D model (JSmol) |
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| ChemSpider | |
| ECHA InfoCard | 100.008.418  |
| E number | E505 (acidity regulators, ...) |
PubChem CID |
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| UNII | |
CompTox Dashboard (EPA) |
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| Properties | |
| FeCO3 | |
| Molar mass | 115.854 g/mol |
| Appearance | white powder or crystals |
| Density | 3.9 g/cm3[1] |
| Melting point | decomposes |
| 0.0067 g/l;[2] Ksp = 1.28 × 10−11 [3] | |
| +11,300·10−6 cm3/mol | |
| Structure | |
| Hexagonal scalenohedral / Trigonal (32/m) Space group: R 3c, a = 4.6916 Å, c = 15.3796 Å | |
| 6 | |
| Related compounds | |
Other anions |
copper(II) carbonate, zinc carbonate |
Other cations |
iron(II) sulfate |
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). | |
| Infobox references | |
Preparation
Ferrous carbonate can be prepared by reacting solution of the two ions, such as iron(II) chloride and sodium carbonate:[4]
- FeCl
2 + Na
2CO
3 → FeCO
3 + 2NaCl
Ferrous carbonate can be prepared also from solutions of an iron(II) salt, such as iron(II) perchlorate, with sodium bicarbonate, releasing carbon dioxide:[5]
- Fe(ClO
4)2 + 2NaHCO
3 → FeCO
3 + 2NaClO
4 + CO
2 + H
2O
Sel and others used this reaction (but with FeCl
2 instead of Fe(ClO
4)2) at 0.2 M to prepare amorphous FeCO
3.[6]
Care must be taken to exclude oxygen O
2 from the solutions, because the Fe2+
ion is easily oxidized to Fe3+
, especially at pH above 6.0.[5]
Ferrous carbonate also forms directly on steel or iron surfaces exposed to solutions of carbon dioxide, forming an "iron carbonate" scale:[3]
- Fe + CO
2 + H
2O → FeCO
3 + H
2
Properties
The dependency of the solubility in water with temperature was determined by Wei Sun and others to be
where T is the absolute temperature in kelvins, and I is the ionic strength of the liquid.[3]
Uses
Ferrous carbonate has been used as an iron dietary supplement to treat anemia.[7] It is noted to have very poor bioavailability in cats and dogs.[8]
Toxicity
Ferrous carbonate is slightly toxic; the probable oral lethal dose is between 0.5 and 5 g/kg (between 35 and 350 g for a 70 kg person).[9]
References
- D R. Lide, ed.(2000): "CRC Handbook of Chemistry and Physics". 81st Edition. Pages 4-65.
- Patty, F., ed. (1963): "Industrial Hygiene and Toxicology"; volume II: 'Toxicology". 2nd ed. Interscience. Page 1053.
- Wei Sun (2009): "Kinetics of iron carbonate and iron sulfide scale formation in CO2/H2S corrosion". PhD Thesis, Ohio University.
- (1995): "Kirk-Othmer Encyclopedia of Chemical Technology". 4th ed. Volume 1.
- Philip C. Singer and Werner Stumm (1970): "The solubility of ferrous iron in carbonate-bearing waters". Journal of the American Water Works Association, volume 62, issue 3, pages 198-202. https://www.jstor.org/stable/41266171
- Ozlem Sel, A.V. Radha, Knud Dideriksen, and Alexandra Navrotsky (2012): "Amorphous iron (II) carbonate: Crystallization energetics and comparison to other carbonate minerals related to CO2 sequestration". Geochimica et Cosmochimica Acta, volume 87, issue 15, pages 61–68. doi:10.1016/j.gca.2012.03.011
- A .Osol and J. E. Hoover and others, eds. (1975): "Remington's Pharmaceutical Sciences". 15th ed. Mack Publishing. Page 775
- "AAFCO methods for substantiating nutritional adequacy of dog and cat foods (proposed for 2014 publication)" (PDF). AAFCO. 2013.
- Gosselin, R.E., H.C. Hodge, R.P. Smith, and M.N. Gleason. Clinical Toxicology of Commercial Products. 4th ed. Baltimore: Williams and Wilkins, 1976., p. II-97