Science Lab: Cleaning a Penny

By Jen Anderson February 10, 2021

Did you know that you can clean your money? Make your dirty pennies bright and shiny again with a little chemistry!

What You Need:

  • ¼ cup vinegar or lemon juice in a glass or plastic bowl
  • 1 teaspoon salt
  • Old, dirty pennies
  • Bowl of water
  • Paper towels for drying

What You Do:

1.) Set up your workspace.

2.) Mix the salt and vinegar together in a non-metal bowl. Add your dirty pennies, making sure they are completely covered by the solution.

3.) Let the pennies sit for 20-30 minutes, or longer if your pennies are super dirty.

4.) Remove the pennies from the vinegar solution and rinse them in a bowl of water. Take them out of the water and dry them with a paper towel.

The Science:

As pennies are exposed to the environment, they become coated with a layer of copper oxide, making them look old and tarnished. Copper oxide dissolves in a mixture of weak acid and table salt. Vinegar and lemon juice are both acids.