Nernst equation

Nernst Equation is a scientific equation used to find the reduction potential or voltage of an electrochemical cell. It is widely used in cell physiology and neurobiology. It is named after Walther Nernst. He was a German chemist who created this equation.

This equation can be used to check which combination of chemicals will be suitable to construct a powerful electric cell.

Expression

Nernst Equation:

$E_{cell}={E^{o}}-{\frac {RT}{zF}}\ln {Q}$

where

E_cell = Reduction potential or voltage of the electrochemical cell.

E = Standard potential of the cell. It is the reduction potential of the cell or voltage under standard conditions (Temperature = 298 Kelvin, Pressure = 1 bar).

R = Gas constant. It is an important constant used in thermodynamics. Its value is 8.314 J.K^-1.mol^-1.

T = Temperature of the electrochemical cell in Kelvin.

z = Number of moles of electrons that got transferred when reduction took place.

F  = Faraday constant. It is equal to the charge carried by 1 mole of electrons. Faraday constant = 96,485.3329 s Ampere/mole.

Q = Reaction quotient of the chemical reaction that is driving the cell.

Equilibrium

When the reduction potential of a cell = 0 V, it is in equilibrium. At equilibrium, the reaction quotient Q = K_eq (equilibrium constant).