Time to test some pennies! In this experiment, you get to test 3 different liquids and see which can make your pennies shine!
Materials:
3 dull pennies, 3 bowls, vinegar, and dish soap.
Time Estimated:
25-30 minutes
Directions:
Add vinegar to one bowl (enough to cover penny)
Add soap to a second bowl (enough to cover penny)
Add water to a third bowl (enough to cover penny)
Make a hypothesis of which liquid will make a penny shine. Your hypothesis can be “If I put the penny in ____, then it will be the shiniest because _____.” Share your hypothesis in the comments!
Wait 20 minutes. While you wait, check-out another experiment!
Rinse pennies and dry with towel. Compare your results! Was your hypothesis on track? Remember, it doesn’t matter if your hypothesis is right or wrong! All that matters is that you test a prediction and learn something. Now, you know for next time and you can tell other scientists what you discovered too in the comments below!
Think Like A Scientist:
What if you left the pennies in the bowls for a longer amount of time? Or a shorter amount of time? Create a hypothesis and try it out. Let us know what you discover in the comments below!
If you run out of vinegar, you can also use other acidic liquids, such as lemon juice or pickle juice. See how they compare! Tell us your favorite liquid in the comments!
Will you find the same results with different coins? Try it out!
How does it work??
Through this experiment, you just learned that acids are good cleaning agents! We can see this because, as you just saw, the vinegar, an acid, is very good at making pennies shiny!
Pennies are covered in copper. Over time, they become dull as the copper reacts with oxygen in the air to form copper oxides. Copper oxides are really dark, and so they make the penny less shiny!
The acetic acid in vinegar breaks down these copper oxides! This effectively removes the dark molecules leaving a shiny penny behind.
Why didn’t soap work? Soap is a very good cleaning agent, as it can separate a lot of molecules. HOWEVER, it is not great at separating copper oxides.
To find out good solutions to our problems, scientists have to do lots of experiments and try lots of different procedures! Before this experiment existed, most scientists would have probably assumed that soap was the best cleaning option. Luckily, other scientists have disproved this hypothesis and shared their findings with others, so now we know to use acid to clean pennies!
Sometimes when experiments disprove your hypothesis, it can actually mean that you found out something new and important! Never be afraid to be wrong or make a mistake! It just means that you got an opportunity to learn something new!
In fact, some of the best inventions have been from mistakes. Sticky notes were created by accident, and now they are used by almost everyone! Can you think of any other invention that was made on accident?
Another example is chocolate chip cookies! One day, a baker didn’t want to take the time to mix in the chocolate into the cookie mix. Instead of dissolving in the oven like they predicted, the chocolate chip cookie was invented! Now it is one of my favorite foods! What about you?
Looking for more fun at home STEM activities for your young scientist? Check out our workbook full of exciting science experiments and empowering activities!
