Solar Energy Education: Home Made Galvanic Cells

This solar energy education experiment is quite involved. Galvanic cells are a clear representation of what is happening inside a battery. Experiencing the operation of these cells through constructing and observing them will help your child to understand the concepts involved with the chemical reactions in batteries.

Materials Needed: You will need the following:

* two drinking glasses
* table salt
* one large iron nail
* some aluminium foil
* some copper wire
* tissue paper
* a length of electrical wire, preferably with alligator clips on each end.

Procedure:

Step 1: Make sure all the metals to be used in this experiment are clean and shiny before use. That will help us to be sure that the results are not due to previous dirt on the metals.

Step 2: IRON and ALUMINIUM: Place a teaspoon of salt in each glass and fill them with water. Stir the water until all the salt in each glass has dissolved. Roll up the tissue paper into a tube, then flatten it. Do the same with the aluminium foil. Then set up the equipment as follows:

What Is Happening?

This experiment is an extension of the Preferential Rusting experiment in the 12+ section. As in that experiment, the aluminium is giving electrons to the iron to stop it rusting and is therefore corroding itself. This time the electrons are traveling through the wire to the iron nail.

This is in effect a very simple, low voltage battery. If you have a very sensitive volt meter or the like you will be able to detect the current passing through the wire.

Extending the Experiment: OTHER COMBINATIONS

This same experiment can also be done with iron / copper and also copper / aluminium. From doing all three of these you will see, as in the Preferential Rusting, that copper is the least likely to rust, then iron, with aluminium as the most reactive metal.

NOTE: The tissue paper is called a "Salt Bridge" and acts to balance out the charges in each glass of water by allowing ion flow from one to the other. It effectively completes the circuit. If it is not present or its ends are not immersed in each glass the circuit will not work and both metals will rust in the salty water.

For full details about the chemical reactions that are occurring in this experiment, see the page make a battery.