How can we clean an old penny?
Hypotheses: Ask children why certain pennies are dirty and tarnished while others are nice and shiny. Ask them what pennies are made of and how we could clean tarnished pennies.
- One tarnished penny per child
- A few shiny pennies to compare with
- One transparent glass per child
- Soap and water
- Lemon juice
- Paper towels
- Begin by observing an old, tarnished penny closely. Do the same with a shiny penny. Name the differences you see.
- Place your glass filled with soap and water in front of you. Drop you tarnished penny in it and let it soak for a few minutes.
- Try rubbing it a little. Is it cleaner?
- Do the same thing again but this time, empty your glass and add a small quantity of lemon juice. Let it soak for approximately 5 minutes.
- Remove your penny and dry it well. What do you notice?
Explanation: Soap and water alone were not sufficient to wash your penny since it is a metallic object. When the oxygen found in the air remains in contact with metal for a long period of time, a layer of filth called "oxidation" forms. To remove it (deoxidation of the metal) we must use a special cleaning product which contains acid. Only acid can destroy the layer of oxidation. It's a chemical reaction! Since lemon juice is an acidic substance, it successfully destroyed the layer of oxidation and cleaned the penny. It made it look brand new! Try the experiment with a different acidic substance like vinegar or Coca-Cola.
has a Bachelor's Degree in Biological Science. She has worked in a laboratory and tested her knowledge. She has taught Math, Chemistry, and Physics. She has also developed a simplistic and innovative approach designed to introduce young children to scientific experiments, old and new. She created her friend Globule. This character is sometimes red, and sometimes white. He guides little ones through their scientific experiments and discoveries. It is clear to see Angélique is passionate about children and science. Globule's Approach.