Green Pennies Science Copper Science Experiment

Why is the Statue of Liberty green? It’s a beautiful patina, but how does it happen? Why not give it a try in your very own kitchen or classroom by making green pennies! This month we have been using pennies quite a bit this month for simple science and St Patricks Day with a sink the pot STEM experiment and an ice melt science activity. Penny science is a classic science experiment for any time learning.

Make Green Pennies and Copper Science Activity

EASY COPPER SCIENCE ACTIVITY AND GREEN PENNIES

So what makes green pennies green?
What is copper?
What does all this have to do with the Statue of Liberty?

I guess it’s time for a little science experiment then! This is truly kitchen science because your main ingredients are already in your kitchen pantry. Grab the white vinegar, salt, water, bowl with a good size bottom base, a teaspoon, paper towels, and of course pennies!

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Get yourself a dozen dull pennies and you can try out a double science activity with both polishing pennies and making green pennies. Either one is a fun science activity in itself but together they make a great science experiment and help kids to further understanding why green pennies and the Statue of Liberty look the way they do!

DULL PENNIES ARE THE BEST TO START WITH…

We know that copper is shiny and bright, so why do these pennies {that are copper} look dull? Well, the atoms in the copper when mixed with oxygen atoms in the air form copper oxide which is the dull surface appearance of the penny. Can we polish it? YES, keep reading!

STEP 1: Prep the green pennies science experiment by filling 2 small bowls with about 1/4 cup of vinegar and a teaspoon of salt each. Mix thoroughly.

STEP 2: Before dropping about 5 pennies into the bowl. Take one and dip it halfway into the bowl. Count to 10 slowly and pull it out. What happened? Add a few more pennies and let them sit for a few minutes. What can you see happening? The mixture of salt and acid {vinegar} dissolves the copper oxide and restores the copper atoms to their shiny state. Make sure to add 6 pennies to the other bowl too.

STEP 3: Now, take the pennies from one bowl and give them a good since and let them dry on a paper towel. Take the other pennies from the other bowl and place them directly on another paper towel. Let’s wait and see what happens. Alternatively, you can try out other acids like lemon juice and other citrus juices and see which ones work best!

Can you see the differences between the two groups of pennies, the rinsed and unrinsed pennies? Do you now have some green pennies? I bet you do! Your dull pennies should either be green or polished!

GREEN PENNIES AND THE STATUE OF LIBERTY

Your green pennies have what is called a patina. A patina is a thin layer that has formed on the surface of your copper penny from “weathering” and oxidization from the chemical process we just put the penny through. The Statue of Liberty is covered in a thin layer of copper. Because she sits out in the elements and is surrounded by salt water, she has a patina similar to our green pennies. It would be a huge job to polish her!