Enaught in Concentration Cells

[Brittney Hun 2C]

If the Enaught is always zero in a concentration cell, then will the Gibbs free energy also be zero?

[Pegah Nasseri 1K]

No, remember that to find the change in gibbs free energy, you need the cell potential. You calculate the cell potential through the equation E = E˚ - (RT/nF) lnQ. This equation incorporates your standard cell potential value but it is not the only value that determines the cell potential. Then you would plug in your cell potential value into delta G = -nFE to find the change in gibbs free energy. So just because E˚ may equal zero, the cell potential is not necessarily zero, and gibbs free energy is not necessarily zero either.

[Charlene Datu 2E]

No, remember that to find the change in gibbs free energy, you need the cell potential. You calculate the cell potential through the equation E = E˚ - (RT/nF) lnQ. This equation incorporates your standard cell potential value but it is not the only value that determines the cell potential. Then you would plug in your cell potential value into delta G = -nFE to find the change in gibbs free energy. So just because E˚ may equal zero, the cell potential is not necessarily zero, and gibbs free energy is not necessarily zero either.

To clarify, you can use that delta G equation to find the spontaneity at those particular concentrations and temperature. However, when you plug in E°, you're calculating delta G° and not delta G?

[Connie Chen 1E]

No, remember that to find the change in gibbs free energy, you need the cell potential. You calculate the cell potential through the equation E = E˚ - (RT/nF) lnQ. This equation incorporates your standard cell potential value but it is not the only value that determines the cell potential. Then you would plug in your cell potential value into delta G = -nFE to find the change in gibbs free energy. So just because E˚ may equal zero, the cell potential is not necessarily zero, and gibbs free energy is not necessarily zero either.

To clarify, you can use that delta G equation to find the spontaneity at those particular concentrations and temperature. However, when you plug in E°, you're calculating delta G° and not delta G?

When you are using the ∆G=-nFE equation, you plug in the E value calculated from E = E˚ - (RT/nF) lnQ, not E˚. So this should give you the ∆G, not the ∆G˚ value.

[aishwarya_atmakuri]

The equation that relates E and delta G uses Ecell and delta G, not delta G naught. As a result, even if Ecell naught is zero, Ecell could not be zero, so delta G does not have to be zero.