- Adult Involvement: Low
Make A Cauldron of Smoking Bubbles
In this science experiment, kids observe carbon dioxide bubbles made by dry ice "melting". Watch how we did this on TV.
Dry ice is frozen carbon dioxide. Carbon dioxide is the same gas that we humans breathe out; it is all around you. As frozen carbon dioxide warms, it goes from being a solid to being a gas without ever becoming a liquid; this is called sublimation. When a cube of dry ice is added to water, it "melts" into gas that bubbles to the top. When the bubbles pop, the carbon dioxide gas coming out sinks down instead of floating up into the air because it is heavier than air.
We added soap so that the bubbles would last longer and form into a mound.
Safety Notes
Dry ice is dangerous and should only be handled by an adult. If touched, it can cause burns. If enclosed in an air-tight container, it can also cause the container to pop open unexpectedly. Always keep children out of reach of the dry ice, always use tongs or thick leather gloves when moving the dry ice, always store it in a container with ventilation, and never attempt to chop or break it in a way that bits could fly up into someone’s face or eyes.
Materials
Instructions
Use a tall, clear container for this activity; this will minimize the chances that a child will come in contact with the dry ice.
Fill your container about 3/4 full with water. Add a few drops of dish soap. Also add food coloring, if desired. Using tongs or very thick gloves (never touch dry ice!), carefully add a chunk of dry ice to the water and soap solution; it will sink to the bottom. Bubbles should start to mound on top of the water. When you pop the bubbles, something that looks like smoke will come out! This is the carbon dioxide gas.
Extensions:
Try adding a glow stick and/or glowing water to make your solution extra spooky!
Try adding more dry ice to make the bubbles form faster.
Try using warmer water to make the bubbles form faster.
Try adding more dish soap to change the way your bubbles look.
