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iron(II) carbonate

Names
Other names ferrous carbonate
Identifiers
CAS Number	563-71-3
3D model (JSmol)	Interactive image
ChemSpider	10774
ECHA InfoCard	100.008.418
E number	E505 (acidity regulators, ...)
PubChem CID	11248
UNII	MZ3Q72U52O
CompTox Dashboard (EPA)	DTXSID8052225
InChI InChI=1S/CH2O3.Fe/c2-1(3)4;/h(H2,2,3,4);/q;+2/p-2Key: RAQDACVRFCEPDA-UHFFFAOYSA-L
SMILES C(=O)().
Properties
Chemical formula	FeCO3
Molar mass	115.854 g/mol
Appearance	white powder or crystals
Density	3.9 g/cm
Melting point	decomposes
Solubility in water	0.0067 g/L; Ksp = 1.28 × 10
Solubility product (Ksp)	3.13×10
Magnetic susceptibility (χ)	+11,300·10 cm/mol
Structure
Crystal structure	Hexagonal scalenohedral / Trigonal (32/m) Space group: R 3c, a = 4.6916 Å, c = 15.3796 Å
Coordination geometry	6
Related compounds
Other anions	iron(II) sulfate
Other cations	copper(II) carbonate, zinc carbonate
Except where otherwise noted, data are given for materials in their standard state (at 25 °C , 100 kPa). Infobox references

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 Fe
and carbonate anions CO
₃.

Preparation

Ferrous carbonate can be prepared by reacting solution of the two ions, such as iron(II) chloride and sodium carbonate:

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:

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.

Care must be taken to exclude oxygen O
₂ from the solutions, because the Fe
ion is easily oxidized to Fe
, especially at pH above 6.0.

Ferrous carbonate also forms directly on steel or iron surfaces exposed to solutions of carbon dioxide, forming an "iron carbonate" scale:

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

${\displaystyle \log K_{\mathit {sp}}=-59.3498-0.041377T-2.1963/T+24.5724\log T+2.518{\sqrt {I}}-0.657I,}$

where T is the absolute temperature in kelvins, and I is the ionic strength of the liquid.

Iron carbonate decomposes at about 500–600 °C (773–873 K).

Uses

Ferrous carbonate has been used as an iron dietary supplement to treat anemia. It is noted to have very poor bioavailability in cats and dogs.

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).

Iron(III) carbonate

Unlike iron(II) carbonate, iron(III) carbonate has not been isolated. Attempts to produce iron(III) carbonate by the reaction of aqueous ferric ions and carbonate ions result in the production of iron(III) oxide with the release of carbon dioxide or bicarbonate.

References

1. D R. Lide, ed.(2000): "CRC Handbook of Chemistry and Physics". 81st Edition. Pages 4-65.
2. Patty, F., ed. (1963): "Industrial Hygiene and Toxicology"; volume II: 'Toxicology". 2nd ed. Interscience. Page 1053.
3. ^ Wei Sun (2009): "Kinetics of iron carbonate and iron sulfide scale formation in CO2/H2S corrosion". PhD Thesis, Ohio University.
4. John Rumble (June 18, 2018). CRC Handbook of Chemistry and Physics (99 ed.). CRC Press. pp. 5–188. ISBN 1138561630.
5. ^ (1995): "Kirk-Othmer Encyclopedia of Chemical Technology". 4th ed. Volume 1.
6. ^ Singer, Philip C.; Stumm, Werner (1970). "The Solubility of Ferrous Iron in Carbonate-Bearing Waters". Journal (American Water Works Association). 62 (3): 198–202. ISSN 0003-150X.
7. 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
8. "Kinetics of Thermal Decomposition of Iron Carbonate". Egyptian Journal of Chemistry. 53 (6): 871–884. 2010-12-31. doi:10.21608/ejchem.2010.1268. ISSN 2357-0245.
9. A .Osol and J. E. Hoover and others, eds. (1975): "Remington's Pharmaceutical Sciences". 15th ed. Mack Publishing. Page 775
10. "AAFCO methods for substantiating nutritional adequacy of dog and cat foods (proposed for 2014 publication)" (PDF). AAFCO. 2013.
11. 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
12. Ronald Rich (2007). "8 Iron through Hassium". Inorganic Reactions in Water (1st ed.). Springer Berlin, Heidelberg. p. 178. ISBN 9783540739616.

• Iron(II) compounds
• Carbonates