Magical Self-Inflating Balloons

During the cold days of winter, it’s easy to get cabin fever. Break up the boredom with this fun, simple science experiment using only a balloon, a measuring tape and a little lung power. With this activity, you and your little scientist can explore the effects of warm and cold air on gases as you watch the balloon *magically* inflate and deflate with the changing temperature!

Materials:

• Balloon
• Measuring Tape (or a bit of string)

Activity:

Blow up your balloon to a desired size and tie it off at the end. Make note of how big it is by measuring it with either a measuring tape or a bit of string. Take your balloon and put it outside in the cold for a little while in a place you can view from inside for about 10 minutes. Measure your balloon again to see how much it has shrunk and watch as it slowly expands again in the warmth of your home. Try this a few times to see how varying times and temperatures can give you different results!

What’s the science behind this *magic*? It’s all about volume! As a gas’s density increases in cold temperatures, it compresses, causing your balloon to shrink in size. When exposed to heat, the air’s density decreases, which re-inflates your balloon as the gases expand.

Further Exploration:

Use the data you collected while experimenting with time and temperatures to answer the questions below. Take it a step further and try this activity on another day to compare results of various temperatures and time frames!

• How long do you need to leave your balloon outside for it to deflate completely?
• How long do you need to keep it inside for it to re-inflate to its original size?