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Iron Redox Reactions

Posted: Mon Aug 15, 2022 2:22 am
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

Re: Iron Redox Reactions

Posted: Mon Aug 15, 2022 2:27 am
by ChenBeier
You are right. We call it rust, the building of iron oxide/ hydroxide.
O2 + 2 H2O + 4 e- => 4 OH-

Re: Iron Redox Reactions

Posted: Mon Aug 15, 2022 2:35 am
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?

Re: Iron Redox Reactions

Posted: Mon Aug 15, 2022 2:49 am
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.

Re: Iron Redox Reactions

Posted: Mon Aug 15, 2022 3:50 am
by Hana
Thank you, that really helped a lot :) :) :)

Re: Iron Redox Reactions

Posted: Mon Aug 15, 2022 6:00 am
by ChenBeier
What is the result.

Re: Iron Redox Reactions

Posted: Tue Aug 16, 2022 1:05 am
by Hana
4〖𝐹𝑒〗^(2+)+10𝐻_2 𝑂+ 𝑂_2=4𝐹𝑒〖(𝑂𝐻)〗_(3(𝑠))+8𝐻^+

Re: Iron Redox Reactions

Posted: Tue Aug 16, 2022 3:16 am
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

Re: Iron Redox Reactions

Posted: Tue Aug 16, 2022 3:26 am
by Hana
But I also found it in a chemistry book :( I cant upload a picture unfortunately

Re: Iron Redox Reactions

Posted: Sat Oct 01, 2022 8:29 am
by Abdularifx
:lol: I still not understand how weathering working, especially for Fe :D :D