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Polar Molecules

What happens when an electrically charged object is brought near a stream of water? This is an easy experiment you can do yourself that shows that water molecules are polar!

Announcer: Frostbite Theater presents... Cold Cuts! No baloney!

Joanna and Steve: Just science!

Joanna: Hi! I'm Joanna!

Steve: And I'm Steve!

Joanna: And this is a piece of PVC pipe!

Steve: And this is a plastic cup that has a hole drilled into the bottom of it. So, when I fill it with water, it leaks out of the bottom.

Joanna: If I charge the pipe, and then bring it close to the stream of water, the water is attracted to it. That's because water molecules are polar molecules.

Steve: Water molecules look a little but like Mickey Mouse. The two hydrogen atoms are bunched up on one side of the oxygen atom. And, while the molecules itself is neutral overall, it has a positive end and a negative end because of the way it's shaped. Molecules, like water, that have an asymmetrical distribution of charge, are called polar molecules.

Joanna: Let's say the pipe has a negative electrical charge. If I bring it close to the stream of water, the water molecule flips so that the positive end is pointed towards the negatively charged pipe. Opposite charges attract, so the water is drawn towards the pipe.

Steve: This is an experiment you can do for yourself at home fairly easily. All you need to do is turn on the faucet so a little bit of water comes out. And then you place a charged object near the water. Any object that'll hold a charge will do. Like, a comb!

Joanna: Or a balloon that you've rubbed on your head!

Steve: Or a plastic pen!

Joanna: Thanks for watching! I hope you'll join us again soon for another experiment!

Steve: This made kind of a mess.

Joanna: It really did.

Let's see if we can make this work better.

Steve: But, it's just water.

Joanna: That's true.

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