100 Days of Science-- #3 Learning About Air Molecules

We had so much fun with our quick science experiment on Bernoulli's principle last week that we decided to try another fun experiment this week.  I'm really loving this 100 Days of Science Challenge! 

This time we talked all about air molecules, how they move, what makes them speed up and slow down, etc.

The only supplies we needed were:

• empty water bottle
• latex balloon
• freezer
• warm water 

First we stretched the balloon over the top of our water bottle and made sure to take note of what both the balloon and the water bottle looked like.

Then we stuck the water bottle in the freezer and set the timer for 30 minutes. During the last few minutes of time we filled up the kitchen sink with warm water.

 When the timer went off we observed that the water bottle had "shrunk" a bit and the balloon looked like it was being sucked in.  

My middle son explained that all the molecules were not moving around as much.  "It's like when we're cold and we want to huddle closer together to share heat!"  Not sure that's the best scientific way to look at it but if it helps him remember that cold molecules take up less space than I'm OK with that.

We then put the cold bottle directly into the warm water and watched closely.  Almost immediately we could see the bottle look like it was filling back up and the balloon puffed up a bit too.

We were kind of bummed that the balloon didn't blow up more than that and the boys asked what would happen if we used HOT water.. would the balloon get even bigger?

We decided to give it a try.  First we put our bottle back in the freezer for another 30 minutes.

We then brought a small pan of water to a boil and as soon as our timer went off we stuck the water bottle into the hot water. 

While the balloon did not blow up much more it did blow up a lot faster!

You can see how fast our balloon shot up; it was actually vibrating a bit from side to side 

We could also feel a lot of pressure pushing out against the sides of the bottle.

It was so neat to see the changes that molecules undergo in normal, hot, and cold temperatures.

Others in this series:

1. Bernoulli's Principle
2. Ecotarium Trip