2013 Final #4

[Michelle_Nguyen_3F]

Given , how would we write the half reactions? Thank you!

[Andrea Medina 1A]

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?

[Pauline Tze 3B]

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

[Paul Adkisson 1D]

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.

[alvarado_natalie_2H]

So we would calculate the electron number from the changes in charges seen in the corresponding half reactions?