Sometimes as we look at the world around us, we see movement without any evidence of why it happens. Consider the following and propose your hypothesis of what causes each.
 Have you lain on your back and watched clouds moving in the air above you? Did you observe anything pushing these clouds? Have you ever wondered what makes the clouds move through the sky? Now shine a flashlight in a dark room and ask yourself the following questions: Do you see small particles in the air? Are any of these particles moving? What could make a dust particle move?

Now it is time to experiment and prove that

Purpose: You are to demonstrate the effect that temperature has on particle motion and volume.

Background:

You have already learned that the particles that make up matter are in constant motion. By increasing the temperature or energy in matter, the molecules speed up and the volume increases. The opposite is also true... by decreasing the temperature or energy in matter, the molecules slow down and the volume decreases.

Materials:

• Balloon
• String
• Marker
• Bunsen burner
• Matches
• Two meter sticks

Procedure:

1. Inflate balloon and tie off opening. (Use no more than eight breaths of air to fill up the balloon.)
2. Wrap string around the widest part of the balloon.
3. Use marker to mark the length of the string.
4. Tie the balloon to the end of one of the meter sticks.
5. Light bunsen burner.
6. Use meter stick to hold balloon at least 500 cm (half of a meter) above the bunsen burner flame.
7. After the balloon has been above the flame for five minutes, move the balloon away from the flame and quickly measure the width of it again.

Data:

 Volume at start: Volume after heating for five minutes:

Analysis:

1. Did the volume of the balloon increase or decrease after it was held above the flame?
2. What kind of an experiment would you suggest doing to prove that cooling the balloon will also change the volume?
Review science safety rules here.

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