Iron Redox Reactions

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Hana
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Iron Redox Reactions

Post by Hana »

Hey :D
I am trying to undertstand the chemistry of Deiorning in drinking water.
As far as I understand, Iron is usually present in ground water as Fe2+ and when oxidized it is converted to Fe3+ which is insoluble in water and precipitates. this is a redox reaction where Fe2+ loses an electron and becomes Fe3+, my question is where does this electron go exactly? oxygen?
the first half redox raction is Fe2+= Fe3+ + e, is this right? the second half reaction is ?

Thanks a lot
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ChenBeier
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Re: Iron Redox Reactions

Post by ChenBeier »

You are right. We call it rust, the building of iron oxide/ hydroxide.
O2 + 2 H2O + 4 e- => 4 OH-
Hana
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Re: Iron Redox Reactions

Post by Hana »

Thank you for the fast reply :)
iron redox in water happens at several different steps but we can say at medium pH Fe(OH)3 is the dominant species.
I have the below two equations
Fe2+ + 3H2O --> Fe(OH)3(s) +3H+ + e
and
O2+ 4H+ + 4e --> 2H2O
Can I combine them into one equation?
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ChenBeier
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Re: Iron Redox Reactions

Post by ChenBeier »

You can but it is wrong, because if you Have H+ you cannot have OH- in same time.
Develop the equation using OH-.
One I have already given.
Hana
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Re: Iron Redox Reactions

Post by Hana »

Thank you, that really helped a lot :) :) :)
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ChenBeier
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Re: Iron Redox Reactions

Post by ChenBeier »

What is the result.
Hana
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Re: Iron Redox Reactions

Post by Hana »

4ใ€–๐น๐‘’ใ€—^(2+)+10๐ป_2 ๐‘‚+ ๐‘‚_2=4๐น๐‘’ใ€–(๐‘‚๐ป)ใ€—_(3(๐‘ ))+8๐ป^+
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ChenBeier
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Re: Iron Redox Reactions

Post by ChenBeier »

No it's not correct. H+ and OH - cannot exist together, because this would be water.

4 Fe 2+ + 8 OH- + 2H2O + O2 => 4 Fe(OH)3
Hana
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Re: Iron Redox Reactions

Post by Hana »

But I also found it in a chemistry book :( I cant upload a picture unfortunately
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Re: Iron Redox Reactions

Post by Abdularifx »

:lol: I still not understand how weathering working, especially for Fe :D :D
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