To start us off this month, you’re going to have a mixture of salt and pepper and your task is to separate them! How can you do it? Set a plate or a bowl out of the two mixed together and give it a try.
Okay, maybe you can come up with a cool technique for getting those apart, but did you know you can use static electricity to do it for you easily?
So what is static electricity? Ever shuffle across the carpet and then reach out for a doorknob only to get a shock when you do so? Ever wonder why that happens? This week we’ll explore the science behind static electricity and figure out how to use it to separate those two substances.
Materials:
- A small plate
- salt
- ground pepper
- a balloon
- a flannel shirt or something to get a static charge
Procedure:
- Combine the salt and pepper on the plate. Mix them up good so it is hard to just pull them apart
- Blow up the balloon and tie it shut
- Rub the balloon vigorously on a flannel shirt (or any shirt should probably do). You’ll know you have the balloon charged up if it starts to crackle or make your hair stand up when you bring it to it
- Hover the balloon over the top of the salt and pepper, and watch what the pepper does!
Explanation:
If properly charged, the balloon will attract the tiny ground pepper flakes immediately out of the salt! Those little bits will be plastered right onto the side of the balloon. But why? First off, when you rub the balloon on the flannel/shirt, there are tiny things called “electrons” that will move from the shirt to the balloon. Electrons are the bits in everything around us that are responsible for heat and electricity moving. Now the balloon is supercharged with these particles.
This charge they have will attract certain pieces to it. Like the hair on your head, maybe the wall (did you try and stick the balloon to the wall?), and to the little pepper pieces. The salt won’t move for reasons that you might understand in chemistry and physics classes in high school.
Experiment further:
Good scientists think of questions they can ask and ways to change a system. Can you? Can you think of other things that the balloon might attract? Roll up a piece of paper into a small tube and see if you can roll it on a table. Here’s a trick: charge up the balloon and then slowly bring it closer to a thin stream of water out of your faucet. It will bend the water out of the way!
I hope you enjoyed this simple experiment and learned a little bit. If you have more questions about this, or need tips about science fair ideas around this topic (or others), contact the author.
Steve Davala is a high school science teacher who likes to write. He also tries to think of things he can do to keep the minds of his own children active.
