Exciting Energy Activities: Sour power

Sour Power

Purpose:

The purpose of this activity is to introduce students to chemical reactions as a source of alternative energy.

Objectives:

As a result of the activity, the student will:

1. Describe how a voltaic battery works.

2. Assess the potential usefulness of chemical reactions as a source of energy.

Materials:

18-gauge copper wire

Wire clippers

Steel paper clip

Sheet of coarse sandpaper

Lemons

Limes

Potato

Apple

TEKS:

5.1A,B 5.2A,B,C,D 5.3A 5.7A 5.8A,C

Procedure:

1. Strip 2 inches of insulation off the copper wire. Clip off the 2 inches of bare wire with clippers.

2. Straighten out the paper clip and cut about 2 inches of the straightened steel wire.

3. Use sandpaper to smooth any rough spots on the ends of the wire and paper clip.

4. Squeeze the lemon gently with your hands. Do not rupture the lemon’s skin. Rolling it on a table with a little pressure works great.

5. Push the pieces of the paper clip and the wire into the lemon so they are as close together as you can get them without touching.

6. Moisten your tongue with saliva. Touch the tip of your wet tongue to the free ends of the two wires.

7. Repeat the experiment with the lime, apple, and potato.

8. Explanation - the lemon battery is called a voltaic battery, which changes chemical energy into electrical energy. The battery is made up of two different types of metals. These are called electrodes, which are the parts of a battery where electric current enters or leaves the battery. The electrodes are placed in a liquid containing an electrolyte, which is a solution that can conduct electricity. In a solution of water and electrolyte, like the acid in the lemon, an excess of electrons collects on one end of the electrodes. At the same time, electrons are lost from the other electrode. Touching your tongue to the wires closes the circuit and allows a small electric current to flow. The tingle felt in your tongue and the metallic taste is due to the movement of electrons through the saliva on your tongue.

Questions:

1. What did you feel on the end of your tongue when you touched it to the wires?

2. Where do you think the energy came from that produced the "tingle"?

3. What other of the items created the same sensation? Which ones did not? Why not?

4. Can you think of anything else that you could use that would produce the "tingle" when connected to the wires?

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