Science with Samantha: Polishing Pennies Experiment

Pennies, which are made out of a metal called Copper, are bright and shiny when first made. When copper mixes with oxygen it causes a chemical reaction that can turn the pennies brown or green and make them look dirty. This process is known as oxidation. We can reverse that chemical reaction by soaking the pennies in an acid. In this case, the salt and vinegar create a chemical reaction that cleans the copper oxide right off your penny! 

Ingredients Needed: Cash Coins Money Pattern 259165

  1. A Few Old Pennies 
  2. ¼ Cup Vinegar 
  3. Tablespoon of Salt 
  4. Glass
  5. Paper Towel 

Some Questions To Prompt The Activity 

  1. Is this penny dirty? If so, does water clean it? 
  2. If it’s not dirty what happened to the penny?
  3. Can a chemical reaction be reversed?
  4. Would something like lemon or ketchup have the same effect of cleaning the pennies?

Experiment Steps:

  1. Pour ¼ a cup of vinegar into a glass and mix in a tablespoon of salt 
  2. Place a couple of dirty pennies into the glass and let them soak for about 10 minutes
  3. Take the pennies out, rinse with water, and dry with a paper towel 
  4. Enjoy the just like new penny! 


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