What is the Nernst equation?

Question

Naomi Aronson · Accepted Answer

#E_(cell)=E_(cell)^@-(RT)/(nF)lnQ#

The Nernst Equation is used to determine the cell potential #E_(cell)# of a galvanic cell. It is given by:

#E_(cell)=E_(cell)^@-(RT)/(nF)lnQ#

Where, #E_(cell)^@# is the cell potential at standard conditions,

#Q# is the reaction quotient ,

#n# is the number of electrons exchanged between the cathode and the anode,

#R=8.3145J/(mol*K)# is the universal gas constant ,

and #F=96485C/("mol "e^-)# is Faraday's constant .

For example, consider the following cell at #25^@C#, where the reaction is:

#2Al(s) + 3Mn^(2+)(aq) -> 2Al^(3+)(aq) + 3Mn(s)#

#[Mn^(2+)] = 0.50 M# and #[Al^(3+)] = 1.50 M#.

#Q=([Al^(3+)]^2)/([Mn^(2+)]^3)#

and #n=6# in this case.

#E_(cell)^@=0.48V#

#E_(cell)=0.48-(8.3145xx298)/(6xx96485)ln(((1.50)^2)/((0.50)^3))=0.47V#

Here is a video that explains in details the Nernst Equation and its uses:
Electrochemistry | The Concentration Cell.

Peyton Adams · Answer

undefined The Nernst equation is a mathematical equation that relates the equilibrium potential of an electrochemical cell to the concentration of ions involved in the cell reaction. It is commonly used to calculate the equilibrium potential (also known as the Nernst potential) for a given ion across a membrane. The equation is expressed as:

$$ E = E^{\circ} - \frac{RT}{zF} \ln\left(\frac{[C_{\text{ion}}]}{[C_{\text{ion}}]_{\text{eq}}}\right) $$

Where:
- $E$ is the equilibrium potential,
- $E^{\circ}$ is the standard electrode potential,
- $R$ is the gas constant,
- $T$ is the temperature in Kelvin,
- $z$ is the charge number of the ion,
- $F$ is Faraday's constant,
- $[C_{\text{ion}}]$ is the concentration of the ion,
- $[C_{\text{ion}}]_{\text{eq}}$ is the equilibrium concentration of the ion.