How to Determine the Maximum EMF That Can Be Generated Around the Perimeter of a Cell

Ions travel between a battery's electrodes.

Electrochemical cells generate electromotive force. This force, also known as voltage, drives electricity through the cell, producing an electric current. The maximum EMF that a cell can produce around its perimeter depends on the metals that make up its electrodes. Electricity flows when these metals differ in reactivity, and the greater the difference in reactivity, the greater the voltage the cell can produce. Various flaws in the cells' structure will in practice lead to a lower EMF than this theoretical maximum.

Instructions

1. Refer to a table of standard electrode potentials, such as the Georgia State University link in the Resources section, to determine each electrode's reduction potential. For example, if the cell contains aluminum and silver electrodes, you will see that aluminum has a potential of -1.66 volts, and silver has a potential of 0.80 volts.

2. Determine the lower of these two values. With this example, the lower value is -1.66, aluminum's reduction potential.

3. Multiply this lower value by -1: -1.66 --- -1 = 1.66.

4. Add this value to the other electrode's potential: 1.66 + 0.8 = 2.46. This is the maximum EMF that the cell can generate around its perimeter.

References

• Purdue University: Electrochemical Reactions
• University of Wisconsin: Using Standard Cell Potentials

Resources

• Georgia State University: Standard Electrode Potentials; Carl Nave
• Pima Community College: Electrochemistry; Silvia Kolchens