Provide an example of the Nernst equation for different redox reactions.

The Nernst equation can be used to calculate the potential of a redox reaction at non-standard conditions.

For example, consider the reaction:

Fe2+ + 2e- → Fe(s)

The standard reduction potential for this reaction is -0.44 V. However, if the concentration of Fe2+ ions is not 1 M, then the potential of the reaction will be different. The Nernst equation can be used to calculate this potential:

E = E° - (RT/nF)ln(Q)

where E is the potential of the reaction, E° is the standard reduction potential, R is the gas constant, T is the temperature in Kelvin, n is the number of electrons transferred in the reaction, F is Faraday's constant, and Q is the reaction quotient.

For the above reaction, if the concentration of Fe2+ ions is 0.1 M and the temperature is 25°C, then the potential of the reaction can be calculated as:

E = -0.44 V - (0.0257 V/K)(ln(0.1/1))(2/2)
E = -0.49 V

This means that the reaction is less favourable at this concentration of Fe2+ ions compared to the standard conditions. The Nernst equation can be used for any redox reaction to calculate the potential at non-standard conditions.