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    • Source: Iron(II) carbonate

      • Iron(II) carbonate, or ferrous carbonate, is a chemical compound with formula FeCO3, 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 CO2āˆ’3.


      Preparation


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

      FeCl2 + Na2CO3 ā†’ FeCO3 + 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 + 2NaHCO3 ā†’ FeCO3 + 2NaClO4 + CO2 + H2O
      Sel and others used this reaction (but with FeCl2 instead of Fe(ClO4)2) at 0.2 M to prepare amorphous FeCO3.
      Care must be taken to exclude oxygen O2 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 + H2O ā†’ FeCO3 + H2


      Properties


      The dependency of the solubility in water with temperature was determined by Wei Sun and others to be




      log
      ā”

      K


      s
      p



      =
      āˆ’
      59.3498
      āˆ’
      0.041377
      T
      āˆ’
      2.1963

      /

      T
      +
      24.5724
      log
      ā”
      T
      +
      2.518


      I


      āˆ’
      0.657
      I
      ,


      {\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 500ā€“600 Ā°C (773ā€“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

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