Hot and cold balloons

What happens when you heat the air inside a balloon? What about cooling the air inside a balloon? It's another experiment that might get you and the entire family "Hooked on Science."

Materials

• 2 balloons
• Box
• Freezer
• Hair dryer

Instructions

STEP 1: Blow up the two balloons to exactly the same size and tie each balloon so the air does not escape.

STEP 2: Place one of the balloons in the freezer.

STEP 3: Place the other balloon in a box and, using the hair dryer, blow warm air onto the balloon.

STEP 4: After about 15 minutes remove the balloon from the freezer and compare the cold balloon to the warm balloon.

Explanation

The warm balloon was bigger when compared to the cold balloon. The reason: Warm air expands and cold air contracts.

Jason Lindsey is a Science Outreach Educator with Hooked on Science. Check out his website "Hooked On Science" at hookedonscience.org for webcasts and experiments that might get you hooked on science. Send him your science questions at jlindsey@hookedonscience.org. More science experiments can be found at www.semissourian.com.