Question

State Nernst equation.

Answer 1

The Nernst equation is used to calculate the voltage of an electrochemical cell or to find the concentration of one of the components of the cell.
The Nernst equation:
Ecell = E0cell - $\left(\frac{RT}{nF}\right)InQ$
Ecell = cell potential under nonstandard conditions (V)
E0cell = cell potential under standard conditions
R = gas constant, which is 8.31 $\frac{(volt-coulomb)}{(mol-K)}$
T = temperature (K)
n = number of moles of electrons exchanged in the electrochemical reaction (mol)
F = Faraday's constant, 96500 coulombs/mol
Q = reaction quotient, which is the equilibrium expression with initial concentrations rather than equilibrium concentrations
Sometimes it is helpful to express the Nernst equation differently:
Ecell = E0cell - $\left({2.303}^{\ast }\frac{RT}{nF}\right)logQ$
at 298K, Ecell = E0cell - $\left(0.0591\frac{V}{n}\right)logQ$