Reduction Potentials

Themes > Science > Chemistry > General Chemistry > Solution and Solubility > Solubility and Redox Reactions > Rate Laws - Cell Potential/Voltage > Reduction Potentials

In each redox reaction (galvanic cell), there is an oxidizer and reducer. Each redox reaction can be broken up into half reactions. The half reactions describe what is happening to each element. For instance:

Cu⁺² + Zn -----> Zn⁺² + Cu

can be broken up into:
Zn -----> Zn ⁺² + 2 e^-
Cu⁺² + 2 e^- ------> Cu

Using a table of reduction potentials, voltage of the cell can be predicted. What this means is that you can look up the voltage fro the Cu⁺² + 2 e^- -----> Cu and the voltage for the Zn⁺² + 2 e^- -----> Zn. Then, you reverse the reaction of Zn⁺² + 2 e^- -----> Zn to create the final reaction, so you reverse the voltage for the reaction from the reduction potential table and add the two together to get the voltage for the cell. For example:

the voltage of Cu⁺² + 2 e^- -----> Cu is .34
and the voltage of Zn⁺² + 2 e^- -----> Zn is -.76
but because you reverse the reaction, you also must make the -.76 a .76.
Finally, add the two together.
The final voltage of the cell is 1.1 volts.

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