Iron(II) carbonate

iron(II) carbonate

Names
Other names ferrous carbonate
Identifiers
CAS Number	563-71-3 N
3D model (Jmol)	Interactive image
ECHA InfoCard	100.008.418
PubChem	11248
InChI InChI=1S/CH2O3.Fe/c2-1(3)4;/h(H2,2,3,4);/q;+2/p-2 Key: RAQDACVRFCEPDA-UHFFFAOYSA-L
SMILES C(=O)([O-])[O-].[Fe+2]
Properties
Molar mass	115.854 g/mol
Appearance	white powder or crystals
Density	3.9 g/cm3[1]
Melting point	decomposes
Solubility in water	0.0067 g/l;[2] Ksp = 1.28 × 10−11 [3]
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	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

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 white ionic solid consisting or iron(II) cations Fe2+
and carbonate anions CO2−
3.^[4]

Preparation

Ferous 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 kelvin, 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]

Toxicity

Ferrous carbonate is moderately toxic; the probable oral lethal dose is between 0.5 and 5 g/kg (between 35 and 350 g for a 70 kg person).^[8]

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. 1 2 3 Wei Sun (2009): "Kinetics of iron carbonate and iron sulfide scale formation in CO2/H2S corrosion". PhD Thesis, Ohio University.
4. 1 2 (1995): "Kirk-Othmer Encyclopedia of Chemical Technology". 4th ed. Volume 1.
5. 1 2 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. http://www.jstor.org/stable/41266171
6. ↑ 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
7. ↑ A .Osol and J. E. Hoover and others, eds. (1975): "Remington's Pharmaceutical Sciences". 15th ed. Mack Publishing. Page 775
8. ↑ 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