How to Make Pennies Turn Green

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We’re on winter break and the science fun continues! With this easy experiment, you’ll create a simple chemical reaction – and help explain to your kids why the once copper-colored Statue of Liberty is now green!

The project was fun from start to finish because first we had to break into Travis’s piggy bank. This meant using a screwdriver (under careful adult supervision of course). We separated out the pennies from the rest of the coins, making it a quick lesson in currency denominations too.

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Place your pennies in a bowl covered with a paper towel.

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Pour white vinegar into the bowl, making sure the paper towel is completely saturated.

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Now observe! We were surprised when the first penny had green spots after only a few hours.

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The next morning, several of them were quite green!

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I honestly have no idea why some of the pennies turned green and others did not, but here’s what’s happening: The metal copper and the acid in the vinegar react with oxygen, and form a new blue material, called malachite.

Make sure to observe under a magnifying glass, too!

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