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Posted: Mon Mar 12, 2018 10:27 am
Are we always supposed to flip one of the half-reactions to give you the MOST positive E value?
Posted: Mon Mar 12, 2018 10:31 am
In most cases, yes. Just focus on flipping the reactions so you have the correct overall reaction equation (one half-reaction must be a reduction, the other an oxidation, and when added together, they must be equivalent to the original reaction).
Posted: Mon Mar 12, 2018 10:39 am
In addition to what was said above, make sure when you add the two half reactions together the electrons cancel out. This helps on the idea of flipping reactions because in one half reaction the electrons must be on the reactant side and in the other half reaction the electrons must be on the product side.
Posted: Mon Mar 12, 2018 10:40 am
This is only true in a GALVANIC CELL - where the chemical reaction is spontaneous. In an electrolytic cell, this is not what we would do (we'd actually do the opposite I'm quite sure), because the reaction is non-spontaneous.
Posted: Wed Mar 14, 2018 10:38 am
Yes. Just make sure the electrons cancel out, and that the reaction with a more negative reduction potential is one being flipped.