Nernst Equation
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Nernst Equation
Aug 26, 2022, 16:45 IST
About Nernst Equation
Cells need not operate at standard state conditions. We can use the equation for the free energy change of a reaction to derive a relationship that tells us how the cell potential changes as the concentrations and/or temperature change. The free energy change for a reaction is Delta G = Delta Go + RT ln Q
where Delta Go is the free energy change for the reaction with reactants and products at standard state activities (1 molar concentrations, 1 atmosphere pressures, pure solids or liquids), G is the free energy change under some other set of conditions, and Q is the reaction quotient for the reaction at the second set of conditions. Because Delta G = − nFECell and Delta Go = − nFEoCell, we can write
−nFECell = −nFEoCell + RT ln Q
Applications of Nernst equation:
- Determination of equilibrium constant for cell reaction:
- Determination of solubility product
- Ionization constant and degree of dissociation of weak acid or weak base:
- Determination of pH of a solution
Find solved example and formula of nernst equation in the following pdf
