pot1.jpg (12026 bytes)

a PLAYCHEM experiment

Faraday's Law, Nernst Equation

The above is a picture of a battery running a light emitting diode. This miniture beacon is powered by four cells in series each consisting of two pennies, one new and one battered, in a diet coke electrolyte.

In this experiment you will create and measure the potential of a number of metals. You will use the  computers using the Vernier LoggerPro® program. You may have previously used this system but a brief description for its use is given in the Experiment-Data sheet the computer will print out when you start.

For good results:

make sure the electrodes and cell holders are clean!

pot3.jpg (14727 bytes)

pot2.jpg (9454 bytes) The set up for the cell is pictured at the left.

Using the clips, you will attach electrodes and measure their potential while dipping in a small amount of soda.

All potentials will be measured against a new undamaged U.S. penny. This is attached to the red electrode holder.

The Experiment-Data sheet will assign you the various electrodes to attach to the black electrode.

The graphical record of your experiment is to be handed in with the EXPERIMENT-DATA sheet and the computer graded printout.
For a typical graphical computer printout, .... PGRAPH

Calculations will involve:
  • Nernst Equation
    E  = Eo -  (RT/nF)lnQ = Eo - (.0592/n)logQ @ 25o
  • Faraday's Law
    F = 96,486 Coulombs/mol e- = 96,486 J/volt mol e-
  • R = 8.314 j/mol K
  • watt = power = 1 joule/sec = volts x amperes
  • coulombs = quantity of electricity = amperes x seconds
  • The relationship of Free Energy and Potential  DG = -nFE

© R.W. Kluiber 1/17/2000