Theory Thursday: Cloud in a Bottle

When I got home today Jake started me to tell about a science project that he watched on the "Amazing Science" DVD we are reviewing. (Look for the review in 2 weeks.)

"You take a plastic bottle and put alcohol in it, and swoosh it around, and put the cap back on. Then you use a drill or pencil or something to put a hole in the bottle. Then you pump it up with air and it goes WHOOOSH!His excitement was a little overwhelming. I knew what we were doing tonight, "Cloud in a Bottle".

It is simple really. Start with a two liter bottle, or any plastic bottle that can handle some pressure. A juice bottle perhaps. (Although I wouldn't try a milk carton.) Put about 1/2 teaspoon of rubbing alcohol in the bottle and "swoosh" it around to coat the bottle with it. Put a hole in the bottle. Now I pre-drilled a hole that fit a rubber fitting I had for our pump, but you can just make a small hole and cover it with duct tape and use a pump with a needle on it. (You know a needle for inflating a ball.) Insert pump end and inflate. We were trying to hit 25-30 psi. Once you get some pressure in it, release the pressure and WHOOOSH! You have a cloud in your bottle.

So why does it happen? I thought you might ask so I looked it up. When pressure is applied to the water in the air the molecules gather together and heat up. When the pressure is released the water molecules separate and cool. As they cool they form a cloud and if they cool further it rains. The alcohol evaporates quicker than water and releases its bond with itself quicker thus the alcohol cloud in the bottle forms quicker and with better visibilty than water would. (check this site for deeper info stevespanglerscience.com)

You may have noticed that there are no pictures in this post. That's because we did a video. Check out how much fun we had trying this out. Do you see our special guest in the background, its the new kid in school.

Now its your turn grab the supplies from the closet, bathroom, and recycle bin and give it a try.