Cell Reactions

[sarahd]

When determining standard Gibbs free energy from cell reactions, are they given to us already balanced for electrons?

[JeffreyL]

When determining deltaG of a half reaction at least, the electrons will already be balanced so you can just plug directly into deltaG=nFE equation. With the deltaG of the whole redox reaction it should be the sum of the deltaG values from the already electron balanced half reactions. The only time where you may need to do more work to find the number of electrons is if you want to calculate E^o from a deltaG of a whole redox reaction. In cases like these, you want to cancel out the electrons involved in both half reactions after adding the half reactions together for the whole redox reaction. The number of electrons left after cancelling out will be the new number of electrons input into any other equations you need like E^o=(-deltaG^o)/nF

[Aminta Chem]

Its best to never assume, so always check to see if things are balanced.