Purpose
To illustrate several principles of batteries by using orange juice to power an electric clock.

Materials

• Magnesium strip or ribbon
• Copper strip
• Orange juice
• Steel wool (not a soap pad)
• Electrical leads (with Alligator Clips)
• Battery powered clock (variety that requires a single 1.5 V AA battery)
• 250 mL beaker

Safety
Do not taste the orange juice

Procedure

1. Clean a strip of magnesium and a strip of copper with steel wool.
2. Pour ~200 mL of orange juice into a 250 mL beaker.
3. Connect an electrical lead to one end of the magnesium strip and submerge the other end in the orange juice. (You could tape it to the side of the beaker).
4. Connect the second electrical lead to one end of the copper strip and submerge the other end in the orange juice on opposite side of the beaker.
5. Connect the other ends of the electrical leads to the battery compartment of a clock that would normally run on a single AA battery.
6. If the clock does not run reverse the electrical leads in the battery compartment.

Results
The second hand will begin to move upon connection to the electrical leads.

Follow-up Teaching Notes

• A voltaic (galvanic) cell is created with the magnesium the anode and the copper the cathode.
• The components of the cell can be changed to explore the key components (i.e. change one of the metal electrodes) of a voltaic (galvanic) cell.

Connections
Electrochemistry, redox reactions, voltaic (galvanic) cells.

Extension
Connect two or more cells in series to generate a higher voltage.

Disposal/Clean-up

• The orange juice can be disposed of down the drain.
• The metal strips (electrodes) can be cleaned and reused.

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