- #1

- 97

- 0

Just having a little trouble understanding the concept of standard cell potential...what is it exactly? I understand that it is compared to a reference potential of 0 for the reaction 2H+ + 2e- -> H2(g). But what does it mean when a given reaction has positive potential (other than the fact that it's spontaneous)? For example, if a given reaction (A -> A2+ + 2e-) has a cell potential of 2V, does that mean the electrons and positive ions in the reaction actually generate a potential of 2 volts (at least relative to the reference potential)?

One of the questions I encountered asked something like this: "Given the following 2 reactions, which one generates more electrons for the circuit when both reactions run to completion (assume standard conditions and same starting concentrations)"?

A --> A2+ + 2e-, E* = 1.00

B --> B2+ + 2e-. E* = 2.00

Apparently, they generate the same number of electrons...how exactly? If one has a higher voltage, wouldn't it give more charges and thus electrons? Further, I tried to look at this mathematically:

deltaG* = -nfE* and

deltaG = deltaG* + RTlnK.

Then at equilibrium,

0 = -nFE* + RTlnK so

nfE* = RTlnK

Well certainly if E* is larger, then K would be larger meaning more products are favored at equilibrium and in turn more electrons, no?

Thanks for any help, much appreciated.