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.[5]
Names | |
---|---|
Other names
ferrous carbonate
| |
Identifiers | |
| |
3D model (JSmol)
|
|
ChemSpider |
|
ECHA InfoCard | 100.008.418 |
E number | E505 (acidity regulators, ...) |
PubChem CID
|
|
UNII |
|
CompTox Dashboard (EPA)
|
|
| |
| |
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] | |
Solubility product (Ksp)
|
3.13×10−11[4] |
+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
|
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 [77 °F], 100 kPa).
Infobox references
|
Ferrous carbonate can be prepared by reacting solution of the two ions, such as iron(II) chloride and sodium carbonate:[5]
Ferrous carbonate can be prepared also from solutions of an iron(II) salt, such as iron(II) perchlorate, with sodium bicarbonate, releasing carbon dioxide:[6]
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.[7]
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.[6]
Ferrous carbonate also forms directly on steel or iron surfaces exposed to solutions of carbon dioxide, forming an "iron carbonate" scale:[3]
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]
Iron carbonate decomposes at about 500–600 °C (773–873 K).[8]
Ferrous carbonate has been used as an iron dietary supplement to treat anemia.[9] It is noted to have very poor bioavailability in cats and dogs.[10]
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).[11]
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.[12]