Question

What is the Nernst potential?

Answer 1

`E=E^@-(RT)/(nF)logQ`

Explanation:

Nernst equation is derived from the thermodynamic expression of free energy: `DeltaG=DeltaG^@+RTlnQ` and we know that `G=-nFE`, therefore, Nernst equation will be:

`E=E^@-(RT)/(nF)logQ`

where `Q` is the reaction quotient, `R` is the universal gas constant `R=8.3145 J/(mol.K)`, `F` is Faraday's constant `F=96485 C/(mol e^-)` and `T` is the temperature in Kelvin.

Example,

RedOx Reaction: `2Al(s) + 3Mn^(2+)->2Al^(3+)+3Mn(s)` at `25^@C`

`E_(cell)=E_(cell)^@-(0.0591)/(6) log([Al^(3+)]^2/([Mn^(2+)]^3))`

where `0.0591=(8.3145xx298)/96485xx2.30` (the conversion factor between ln and log ")

Here is a video that explains this equation further: