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Electrochemical Potentials

The Electrochemical Potential is a measurement of the energy stored in the chemical potential of redox reactions. The Electrochemical Potential can be calculated by adding up the electrode potentials of each half-cell. These individual half-cell potentials can be calculated by standardizing its reducing or oxidizing potential to the standard hydrogen electrode (SHE). The difference in electrode voltage with the SHE gives a predictive value of the half-cell potential.

However, before one can start to calculate the Electrochemical Potential, one must first manipulate the half-cell reactions to make sure that the right cell is either undergoing reduction or oxidation. The half-cell with the smallest potential and integer sign must be reversed to create an overall positive cell potential. Consider the following redox reaction:

Cu2+(aq) + Zn(s) --> Cu(s) + Zn2+

Reducing half-cell:
Cu2+(aq) + 2e- --> Cu(s)
E = 0.34 V

Zn(s) --> Zn2+(aq) + 2e-
E = 0.76 V

It can be seen that the reduction potential of Cu2+ is 0.34V and the oxidizing potential of Zn is 0.76. Adding the two values together gives a total electrochemical potential of 1.10 V. Thus, it is can be seen that understanding electrochemical potentials in the context of electrochemical cells is important for the study of electrochemistry.


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