Try This at Home: Balloon on a Bottle
Illustrated Concepts
Gases expand, or take up more space, when they are heated. As a gas becomes warmer, its molecules move further apart.
What You Need
-
1 plastic 2-liter bottle, empty
-
1 large bowl or baking pan
1 balloon
-
Water
What To Do
-
Make sure you have an adult with you to supervise this experiment.
-
Fill the bottle with cold water and put it in the freezer for up to an hour. Do not let the water freeze.
-
Fill the bowl with hot tap water.
-
Empty the cold water out of the bottle, then pull the balloon over its mouth. Set the bottle in the bowl of hot water.
-
What happens when the cold air inside the bottle becomes warm?
-
Clean up. Use caution when handling the hot water and bowl.
What's Happening
Most things expand when they are heated and contract when they are cooled. This occurs with solids and liquids, but it is most noticeable with gases. The cold water cools the plastic bottle, and after the water is poured out, the cold bottle cools the air inside it. When the bottle is placed in hot water, the air inside it warms and expands. The molecules that make up the air inside the bottle move apart and take up more space. When the air takes up more room than the bottle can hold, it inflates the balloon.
Fun Fact
Triton, the largest moon of Neptune, is one of the coldest places in the solar system– it has "cryovolcanoes" that erupt with liquid nitrogen.