Iron Redox Reactions

[Hana]

Hey
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

[ChenBeier]

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

[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?

[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]

Thank you, that really helped a lot

[ChenBeier]

What is the result.

[Hana]

4〖𝐹𝑒〗^(2+)+10𝐻_2 𝑂+ 𝑂_2=4𝐹𝑒〖(𝑂𝐻)〗_(3(𝑠))+8𝐻^+

[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]

But I also found it in a chemistry book I cant upload a picture unfortunately

[Abdularifx]

I still not understand how weathering working, especially for Fe