Green Pennies Experiment - Little Bins for Little Hands

Why is the Statue of Liberty green? It’s a beautiful patina, but how does it happen? Explore the science in your own kitchen or classroom by making green pennies! Learning about the patina of pennies is a classic science experiment for any time learning!

HOW TO MAKE GREEN PENNIES

Green Pennies, polishing pennies, and copper science for kids

PENNY EXPERIMENTS

Science experiments with things found in your purse or pocket? Get ready to add this simple penny experiment to your science activities this season. If you want to learn about how to turn pennies green and what cleans them, let’s dig in! While you’re at it, make sure to check out our other penny experiments.

Our science activities and experiments are designed with you, the parent or teacher, in mind! Easy to set up, quick to do, most activities will take only 15 to 30 minutes to complete and are heaps of fun! Plus, our supplies lists usually contain only free or cheap materials you can source from home!

green pennies from ordinary pennies copper science

WHY DO PENNIES TURN GREEN?

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 project 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 to find out!

Adding the green pennies to a mixture of salt and acid {vinegar} dissolves the copper oxide and restores the copper atoms to their shiny state.

Click here to get your FREE printable Science Pack!

PENNY SCIENCE EXPERIMENT

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

SUPPLIES:

white vinegar
salt
water
bowl with a good size bottom base
a teaspoon
paper towels
pennies

PENNY EXPERIMENT SET UP:

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?

Make sure to add 6 pennies to the other bowl too.

STEP 3: Now, take the pennies from one bowl, rinse them 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!