Sublimating dry ice is covered with a soap bubble that
grows and grows (until it collapses!)
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Teachable Topics:
- Sublimation
- Surface Tension
Theory:
When dry ice sublimates, the carbon dioxide gas has many times the volume of the ice. When a soap film is placed over the top of a beaker of sublimating dry ice, it fills with the gas. The bubble formed keeps growing and growing until the pressure of the gas is too much and it bursts.
Since carbon dioxide gas is actually heavier than air, the bubble rolls over the side of the beaker.
Apparatus:
- dry ice
- beaker
- dish soap
- water
- long balloon or cloth
Procedure:
- Place some chunks of dry ice in a beaker.
- Pour some water into the beaker to help the dry ice sublimate faster.
- Take a long balloon or cloth and coat it with a soapy water solution (or better yet, bubble solution).
- Drag the balloon or cloth over top of the beaker to create a bubble over the top. This may take a few tries to get right.
- Once the bubble is formed it should grow and pop. If it does not, try adding more water to your dry ice or try adding more soap to your bubble solution.
Safety:
• If you touch dry ice with your skin you can get frostbite very quickly. Wear cryogenic gloves or oven mitts when handling it.
