Question

Question #8da28

Answer 1

Cell potential is the difference in electric force between elements that are capable of redox reactions. They are measured against a “Standard Hydrogen Electrode” for consistency.

Explanation:

Thus, ALL electrode potentials are listed as reductions and the sign must be reversed when it is the oxidation cell of an electrochemical system.

A good discussion and examples can be found here:
http://www.chem.purdue.edu/gchelp/howtosolveit/Electrochem/Electrochemical_Cell_Potentials.htm