Kids, how can you make a bubble as big as a crystal ball and filled with a smoky haze? All you need to make such a large bubble is dry ice, bubble solution, and a little water. Dry ice sublimes to form carbon dioxide gas, which in turn is used to form and expand the bubble.
Please note: All chemicals and experiments can entail an element of risk, and no experiments should be performed without proper adult supervision.
The supplies you will need are dry ice, a bubble solution, water, and a glass or small glass bowl. To make the bubble: (a) pour some water into the container; (b) have an adult partner add a small piece or two of dry ice using tongs. The dry ice will make bubbles in the liquid; (c) spread a film of bubble solution around the lip of the container; (d) your adult partner can then carefully use their wet, soapy hand or a piece of paper towel that has been wetted with bubble solution to smear bubble solution across the top of the container. (There is a video provided within the link below so you can see how it’s done).
Variations: (1) adding a little highlighter ink to the bubble solution will make the bubble solution glow. (2) Use tonic water instead of regular water and shine a black light (UV light) on the bubble; the quinine molecules in the tonic water will glow (“fluoresce”).
How It Works
Dry ice sublimes in air, meaning the solid carbon dioxide goes through a phase change to carbon dioxide gas. This process occurs much more quickly in water than in air. As the dry ice sublimes, the carbon dioxide vapor is caught inside the bubble solution. The bubble expands, but the cooled bubble solution does not evaporate quickly so the bubble lasts for a relatively long time.
Sometimes conditions are right for the bubble to stabilize at a given size. This happens because carbon dioxide is able to diffuse across the bubble surface. Subliming carbon dioxide expands the bubble, but when the bubble expands its walls become thinner and leak more. Since more carbon dioxide can escape, the pressure is reduced and the bubble has a tendency to shrink back again. As long as the solution doesn't evaporate too quickly, the bubble may remain relatively stable until the dry ice is nearly gone. At that point the bubble will become smaller.
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Kathleen Carrado Gregar, PhD, Argonne National Labs
[email protected]
April 2009
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References: Dr. Anne Marie Helmenstine at http://chemistry.about.com/od/dryiceprojects/a/dryicebubble.htm
