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### 2013 Final #4

Posted: Mon Mar 13, 2017 4:08 pm
Given $2Fe(s) + 2H_{2}O(l) + O_{2} \rightarrow 2Fe(OH)_{2} (s)$, how would we write the half reactions? Thank you!

### Re: 2013 Final #4

Posted: Mon Mar 13, 2017 10:09 pm
I have a similar question how would we know the moles of electrons if we are not given the charges and Fe is a transition metal?

### Re: 2013 Final #4

Posted: Tue Mar 14, 2017 10:52 pm
2Fe(s) + 2H2O --> 2Fe(OH)2(s) + 4e-
pay attention to the charge for Fe as Fe is oxidized from 0 to +2
O2 + 4e- ----> 2Fe(OH)2(s)
pay attention to the charge for O as O is reduced from 0 to -2

### Re: 2013 Final #4

Posted: Wed Mar 15, 2017 11:00 pm
Wait, How would that work? The reduction reaction isn't balanced (Fe on products but not in reactants). I also had trouble determining n for this question.

### Re: 2013 Final #4

Posted: Sat Mar 18, 2017 2:29 pm
So we would calculate the electron number from the changes in charges seen in the corresponding half reactions?