Equilibrium Electrochemistry

•Chemical reactions in electrochemical cells and Nernst Equation •Combining standard Electrode Potentials to determine the cell potential •Obtaining reaction Gibbs Energies and Reaction Entropies from cell potentials •Relationship between the cell EMF and the equilibrium constant.

Chemical reactions in electrochemical cells and Nernst Equation

Electrochemical Cell

ZnSO4 solution

CuSO4 solution

Potentiometer with sliding contact

+

The direction of spontaneous change in the cell can be reversed by changing the electrochemical potential of the electrons in one of the electrodes relative to that in other electrode using an external voltage source.

If this reaction is carried out reversibly,

Nernst Equation at 298.15 K,

The Nernst equation allows the emf for an electrochemical cell to be calculated if the activity is known for each species and E0 is known.

Combining standard Electrode Potentials to determine the cell potential

Example

Obtaining reaction Gibbs Energies and Reaction Entropies from cell potentials

Relationship between the cell EMF and the equilibrium constant.

Example