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Orange Clock
Recommended Grade Level(s):
Appropriate for: All grade levels
Time Requirements:
Activity Time: 15 minutes
Teaching Topics & Concepts:
• Electrochemistry
• Cell potential
• Metal activity
• Anode vs. Cathode
Background:
A battery uses chemical reactions to make electricity. The type of chemicals used depends on how the battery is made or being
used. For example, alkaline batteries (or cells) are used in clocks, flashlights, remote controls, and toys.
Alkaline cells use three main chemicals: zinc, manganese dioxide, and potassium hydroxide. The reaction between these chemicals
moves tiny, negatively charged particles called "electrons" around to create an electric current. For example, when you connect the
cell to a circuit — like a light bulb — the zinc inside reacts with the manganese dioxide and loses electrons.
The electrons are collected by a metal rod inside the cell, which allows them to flow from the bottom of the cell (the negative
terminal), through the wires to the bulb (making it light up), and then back into the top of the cell (the positive terminal).
Students can 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 (the variety that requires a single 1.5V AA battery)
• 250 mL beaker
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Safety
• Read the SDS sheets for all chemicals before using them.
• Wear safety glasses and gloves.
• Magnesium metal is a flammable solid. Avoid contact with flames and heat.
• Do not taste the orange juice! Any food-grade items that have been brought for lab use only.
Do not taste or ingest any materials in the laboratory, and do not remove any remaining food
items after they have been used in the lab.
• Wear chemical splash goggles, chemical-resistant gloves, and a chemical-resistant apron.
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