Molar mass 115.854 g/mol Appearance white powder or crystals | Density 3.9 g/cm³ | |
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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.
Contents
Preparation
Ferrous carbonate can be prepared by reacting solution of the two ions, such as iron(II) chloride and sodium carbonate:
FeCl2 + 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(ClO4)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 Fe2+
ion is easily oxidized to 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:
Fe + CO2 + 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.
Uses
Ferrous carbonate has been used as an iron dietary supplement to treat anemia.
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).