Grade Level: 6th to 8th; Type: Chemistry
This project explores the effectiveness of various cleaning solutions in cleaning tarnished and oxidized coins.
- Do the coins become clean or do they remain tarnished or oxidized?
- Which cleaning solution works best?
- How much effort does it take?
- Do the copper pennies get cleaner than the other coins?
- Do the oxidized coins get cleaner than the tarnished coins?
- Six pennies (tarnished or oxidized)
- Six nickels (tarnished or oxidized)
- Six dimes (tarnished or oxidized)
- Six quarters (tarnished or oxidized)
- One cup dish liquid
- One cup lemon juice
- One cup orange juice
- One cup water
- One cup cola
- One cup baking soda paste (Mix baking soda with water for a paste consistency.)
- 24 cups
- Six plastic spoons
- Six toothbrushes
- Newspaper or art cloth (to cover the table)
- Latex gloves (optional)
- Fill four cups each one quarter full with each of the six cleaning solutions suggested (4 with lemon juice, 4 with orange juice, 4 with cola, 4 with water, 4 with baking soda paste and 4 with dish liquid). Label the cups.
- Carefully record each coin’s condition prior to placing it into its cup.
- Place one of each type of coin into each solution.
- Let all coins soak overnight.
- Using the plastic spoons and latex gloves, scoop each coin out of its cup and place it on the covered table. Take care to label and keep track of which coin came from which solution.
- Examine the coins and record what you see before you start using the toothbrushes.
- Use the toothbrushes to clean the coins, rinse with water, re-examine the coins, and record your observations.
- Address the research questions.
Terms/Concepts: oxidation, tarnish, chemical
- Tips for cleaning coins: How to clean the old dirty coins in your collection
- Easy ways to clean coins, by Scott Damon.
- What juice or liquid cleans pennies the best?, by Ted Mooney
Warning is hereby given that not all Project Ideas are appropriate for all individuals or in all circumstances. Implementation of any Science Project Idea should be undertaken only in appropriate settings and with appropriate parental or other supervision. Reading and following the safety precautions of all materials used in a project is the sole responsibility of each individual. For further information, consult your state’s handbook of Science Safety.