Bright as a Penny

What's the best way to clean a penny? What chemicals do the best cleaners have in common? The kids and I aimed to find out...

Materials you'll need

Step-by-step tutorial

  • Step 1

    We were curious to find out if we could figure out a good way to clean a penny. What would it take?

    Photo reference of how to complete step 1

  • Step 2

    Madeleine went to the fridge, and chose a few things that she thought had potential cleaning power. Pickle juice, ketchup, lemon juice, and vinegar and oil salad dressing. We put a tablespoon or so into little cups.

    Photo reference of how to complete step 2

  • Step 3

    And we chose four pennies that looked to be about the same color...and one very shiny one with which to compare them. Pennies turn dark because their copper atoms combine with oxygen (our air) and form copper oxide. We are hoping that acid will get rid of that outer coating, and restore our pennies to their shiny, beautiful selves.

    Photo reference of how to complete step 3

  • Step 4

    We plopped one penny into each liquid, and left them in there for about 10 minutes.

    Photo reference of how to complete step 4

  • Step 5

    Okay! Now it was time to see if anything has happened. We took the penny out of the messy ketchup....

    Photo reference of how to complete step 5

  • Step 6

    Maddie was thrilled to see how clean the "ketchup penny" was! She cleaned it off with a paper towel, and put that one next to the ketchup cup, so we know which cup it came from...

    Photo reference of how to complete step 6

  • Step 7

    Next one. And clean it...

    Photo reference of how to complete step 7

  • Done!

    Oooh! Ketchup is the cleanest! But not very shiny. Lemon juice is a very close second! And pickle juice not very far behind. Oil and vinegar is the shiniest, and is taking it off the oxidation bits and pieces. What would happen if we left them for longer? And what would make the pennies shiny again? Salt? Baking soda? Why don't you go find out? Scientific minds want to know!

    Photo reference of how to complete step 8

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