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Safety Tips * Dry ice is very cold so don't touch or eat it; leave all handling to an adult partner who should wear non-plastic gloves and use tongs. * Don't ever seal dry ice into a closed container. * Freshly frozen fizzy fruit is the same temperature as dry ice (around -109°F) so allow it to warm a bit before consuming it. |
Kids, what could make pieces of fruit act like fizzy ice cubes? Carbon dioxide! Using dry ice, which is the solid form of CO2, fruit can be filled with tingly carbon dioxide bubbles, like a soda. All you need for this is dry ice, fruit, and a plastic bowl.
Please note: All chemicals and experiments can entail an element of risk, and no experiments should be performed without proper adult supervision.
- First, carbonate the fruit. Use dry ice that’s in relatively small chunks, like pellets or chips. If you have big chunks, have an adult partner place the dry ice in a paper bag or cover it with a dishcloth and whack it (gently) with a hammer. You want to break it into pieces, not pulverize it.
- Dry ice quickly sublimes into carbon dioxide gas. As this happens, the gas is pushed into the fruit. Thinner slices or pieces of fruit will become more saturated with carbon dioxide bubbles than larger pieces. You can use whole grapes or strawberries, but anything larger needs to be sliced, such as apples or bananas.
- Place some dry ice pellets in a bowl. Set the fruit on the dry ice. You can add more dry ice on top if you wish.
- Allow 10-15 minutes for the dry ice to sublime. The fruit will become carbonated and freeze at the same time. Use tongs to handle the pieces.
- Eat the fizzy fruit, use it in recipes or add it to drinks as “ice cubes”. The fruit will remain fizzy as it thaws, but it should be used within an hour because it will lose its bubbles.
What’s going on? Sublimation is a transition directly from the solid phase to gas phase without going through a liquid stage. Vaporization, on the other hand, is a phase transition from the liquid phase to gas phase, and includes both evaporation and boiling.
Tip: Some Meijer stores sell dry ice behind their counters, and you can try some ice cream stores for their supply. In the Chicago area you can also check http://www.solidco2.com and http://www.langice.com
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Kathleen Carrado Gregar, PhD, Argonne National Labs
[email protected]
January 2009
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Reference: Dr. Anne Marie Helmenstine at: http://chemistry.about.com/od/ediblescienceprojects/a/carbonatedfruit.htm?nl=1
