This fun and simple activity shows how water vapor in the air condenses on cold surfaces to become dew and how on very cold surfaces, that condensation freezes and becomes frost! Use this experiment to see how changing temperatures transform water through all three states of matter — gas (water vapor), liquid (water droplets), and solid (frost crystals).
For this experiment, you will need:
- a metal bowl or container (such as an old coffee can)
- two dozen ice cubes
- cold water
- 1/2 cup of salt
- lid or plastic wrap to cover your metal container
- magnifying glass (optional)
Phase 1: Making Dew (Condensation)
Place your metal bowl on a waterproof surface. Put twelve ice cubes in the bowl and pour in enough cold water to cover them. Let it sit for 10 minutes and then examine the outside of the bowl. Record your observations.
Explanation:
It may seem that water is seeping through your metal bowl! Actually, there is always some water in the air in the form of water vapor. We can’t see these water molecules because they are spread out and moving quickly with other gas molecules in the air. When the air touches the cold outside of the metal bowl, the cold temperature slows the water molecules down and they begin to condense (which means “come together”) on the side of the bowl. After a few minutes, there are so many water molecules stuck to the side of the bowl that they start to form droplets and even drip onto the table!
When the temperature cools down at nighttime, water vapor from the air condenses on objects such as grass and leaves, forming dew. You can learn more about dew by reading this article from National Geographic.
Phase 2: Making Frost
Empty and dry your bowl. Next, place the remaining twelve ice cubes in the bowl and add the 1/2 cup of salt. Stir. Cover with a tight-fitting lid or plastic wrap secured with a rubber band. Wait twenty minutes and then use your magnifying glass to inspect the outside of the bowl. Record your observations. Learn more about frost formation from National Geographic, and read about how your salt super-cooled your ice at Sciencing.com.
