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Saturday, July 23, 2011

Shiny Pennies

You may know that U.S. pennies are made with copper, which gives them a brown color. New pennies are a bright, shiny, orange-brown, but over time, they become darker and duller. What happens to them?

The pennies are oxidizing, which means that they react with oxygen in the air. This forms a coating of copper oxide. But never fear, you can make your pennies shiny again!

What You'll Need:

Several dull pennies
Coca-Cola (not diet)
Plastic cup

Pour a few inches of Coke into the cup, and add the pennies. Let the pennies sit overnight, and check them the next morning. They will be shiny again!

IMPORTANT: Do not drink the Coke after the pennies have sat in it.

What did the Coke do to the pennies? Coke contains phosphoric acid, which reacts with the copper oxide and converts it back into copper metal. Other acids will do the same thing. Try putting pennies in lemon juice (citric acid) or vinegar (acetic acid).

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