:Iron(II) carbonate
{{short description|Chemical, compound of iron carbon and oxygen}}
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| Name = iron(II) carbonate
| OtherNames = ferrous carbonate
|Section1={{Chembox Identifiers
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| UNII = MZ3Q72U52O
| InChI = 1S/CH2O3.Fe/c2-1(3)4;/h(H2,2,3,4);/q;+2/p-2
| InChIKey = RAQDACVRFCEPDA-UHFFFAOYSA-L
| SMILES = C(=O)([O-])[O-].[Fe+2]
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| CASNo = 563-71-3
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| PubChem = 11248
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|Section2={{Chembox Properties
| Formula = FeCO3
| MolarMass = 115.854 g/mol
| Appearance = white powder or crystals
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| MeltingPt_notes = decomposes
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| Solubility = 0.0067 g/L; Ksp = 1.28 × 10−11
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| SolubilityProduct = 3.13{{e|−11}}{{cite book |author1=John Rumble |title=CRC Handbook of Chemistry and Physics |date=June 18, 2018 |publisher=CRC Press |isbn=978-1138561632 |pages=5–188|edition=99 |language=English}}
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| MagSus = +11,300·10−6 cm3/mol
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|Section3={{Chembox Structure
| Coordination = 6
| CrystalStruct = Hexagonal scalenohedral / Trigonal ({{overline|3}}2/m)
Space group: R {{overline|3}}c, a = 4.6916 Å, c = 15.3796 Å
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|Section4={{Chembox Thermochemistry
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|Section8={{Chembox Related
| OtherAnions = iron(II) sulfate
| OtherCations = copper(II) carbonate, zinc carbonate
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Iron(II) carbonate, or ferrous carbonate, is a chemical compound with formula {{chem|Fe|C|O|3}}, that occurs naturally as the mineral siderite. At ordinary ambient temperatures, it is a green-brown ionic solid consisting of iron(II) cations {{chem|Fe|2+}} and carbonate anions {{chem|C|O|3|2-}}. The compound crystallizes in the same motif as calcium carbonate. In this motif, the carbonate dianion is nearly planar. Its three oxygen atoms each bind to two Fe(II) centers, such that the Fe has an octahedral coordination geometry.{{cite journal |doi=10.1524/zkri.1981.156.3-4.233 |title=Crystal structure refinements of magnesite, calcite, rhodochrosite, siderite, smithonite, and dolomite, with discussion of some aspects of the stereochemistry of calcite type carbonates |journal=Zeitschrift für Kristallographie - Crystalline Materials |date=1981 |volume=156 |issue=3–4 |pages=233–243 }}
Preparation
Ferrous carbonate can be prepared by reacting solution of the two ions, such as iron(II) chloride and sodium carbonate:
: {{chem|Fe|Cl|2}} + {{chem|Na|2|C|O|3}} → {{chem|Fe|C|O|3}} + 2{{chem|Na|Cl}}
Ferrous carbonate can be prepared also from solutions of an iron(II) salt, such as iron(II) perchlorate, with sodium bicarbonate, releasing carbon dioxide:
: {{chem|Fe}}({{chem|Cl|O|4}})2 + 2{{chem|Na|H|C|O|3}} → {{chem|Fe|C|O|3}} + 2{{chem|Na|Cl|O|4}} + {{chem|C|O|2}} + {{chem|H|2|O}}
Sel and others used this reaction (but with {{chem|Fe|Cl|2}} instead of {{chem|Fe}}({{chem|Cl|O|4}})2) at 0.2 M to prepare amorphous {{chem|Fe|C|O|3}}.
Care must be taken to exclude oxygen {{chem|O|2}} from the solutions, because the {{chem|Fe|2+}} ion is easily oxidized to {{chem|Fe|3+|link=Fe3+}}, 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:
: {{chem|Fe}} + {{chem|C|O|2}} + {{chem|H|2|O}} → {{chem|Fe|C|O|3}} + {{chem|H|2}}
Properties
The dependency of the solubility in water with temperature was determined by Wei Sun and others to be
:
\log K_{\mathit{sp}} = -59.3498 - 0.041377 T - 2.1963/T + 24.5724 \log T + 2.518 \sqrt{I} - 0.657 I,
where T is the absolute temperature in kelvins, and I is the ionic strength of the liquid.
Iron carbonate decomposes at about {{Convert|500-600|C|K}}.{{Cite journal |date=2010-12-31 |title=Kinetics of Thermal Decomposition of Iron Carbonate |journal=Egyptian Journal of Chemistry |volume=53 |issue=6 |pages=871–884 |doi=10.21608/ejchem.2010.1268 |issn=2357-0245|doi-access=free }}
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.{{cite web|date=2013|title=AAFCO methods for substantiating nutritional adequacy of dog and cat foods (proposed for 2014 publication)|url=https://www.aafco.org/Portals/0/SiteContent/Regulatory/Committees/Pet-Food/Reports/Pet_Food_Report_2013_Midyear-Proposed_Revisions_to_AAFCO_Nutrient_Profiles.pdf|publisher=AAFCO}}
Toxicity
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.{{cite book |author1=Ronald Rich |title=Inorganic Reactions in Water |date=2007 |publisher=Springer Berlin, Heidelberg |isbn=9783540739616 |page=178 |edition=1st |url=https://doi.org/10.1007/978-3-540-73962-3 |language=en |chapter=8 Iron through Hassium|doi=10.1007/978-3-540-73962-3 }}
References
(1995): "Kirk-Othmer Encyclopedia of Chemical Technology". 4th ed. Volume 1.
D R. Lide, ed.(2000): "CRC Handbook of Chemistry and Physics". 81st Edition. Pages 4-65.
A .Osol and J. E. Hoover and others, eds. (1975): "Remington's Pharmaceutical Sciences". 15th ed. Mack Publishing. Page 775
{{carbonates}}
{{iron compounds}}
{{Antianemic preparations}}