rstar
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FeCO3 oxidation
Hi,
I just bought some HCl that looks yellowish (may be contaminated with Fe), and made some FeCl2 solution.
I added some NaHCO3 and FeCO3 precipitated. And i let it settle down. After some 15 mins i saw that some of it had vanished and there was some red
stuff floating on surface.
I belive it is Fe2(CO3)3 .
Can anyone state the equation for the oxidation of FeCO3 ?
"A tidy laboratory means a lazy chemist "
- Jöns Jacob Berzelius
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DraconicAcid
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What is probably happening is that the FeCO3 isn't terribly insoluble, and you get a small but finite concentration of Fe2+ in solution. Since this
is exposed to oxygen in the air, and you have a basic solution, you get 4 Fe2+ + 8 OH- + O2 + 2 H2O --> 4 Fe(OH)3. Solutions of iron(II) are
generally kept acidic to prevent this reaction.
Please remember: "Filtrate" is not a verb.
Write up your lab reports the way your instructor wants them, not the way your ex-instructor wants them.
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blogfast25
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This has been covered elsewhere. Fe(III) carbonate is unlikely to exist, just like Cr(III) carbonate and Al(III) carbonate don't exist, at least not
in watery media.
Your red stuff is ferric oxide hydrate. I've seen wet FeCO3 (insoluble) oxidise in air to ferric oxide hydrate quite quickly several times...
[Edited on 13-3-2013 by blogfast25]
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