Water Has a Skin
June 3, 2010 by Jerry
Filed under Science Experiments, Things To Do
This is an easy and fun thing to try right now because you can make up so many different stories to go with it.
I’m sure you have everything you need in your kitchen… a bowl, some pepper, and dish washing detergent (or regular soap).
Here’s the set up:
1) Fill the bowl with water.
2) Sprinkle pepper all over the water. It will float on top.
3) Touch your fingertip to the dish washing detergent to get just a tiny bit on your finger.
Now the interesting part!
Most of the pepper will be floating on the water because it’s actually resting on top of it. The water molecules hold together in sort of a “skin” that holds up each bit of pepper. This skin is called surface tension.
Now, gently touch your finger to the water at the middle of the bowl. The pepper races away from your finger!
The soap suddenly breaks this “skin” and makes a tiny wave of water as it does. This pushes the pepper away from your finger, where it now sinks to the bottom.
Try it and see for yourself. You’ll have to rinse out the bowl and start over to try it again.
You can make up some fun stories to go with this. Sprinkle the pepper and say, “Look at all the little mice! My finger is the cat. Watch them run!”
What stories can you come up with?
