Colorful column of balloons

Blow up a balloon with solid carbon dioxide

Dry ice in a containerMost substances have three states – solid, liquid, and gas. When they go from a solid to a gas, they usually turn into a liquid in between. Ice is a good example. It first melts into a liquid and then evaporates into a gas. Sublimation is when a chemical compound turns from a solid to a gas without turning into a liquid in between. Solid Carbon dioxide (or dry ice) and iodine are two compounds that sublime. When dry ice sublimes, it turns directly into carbon dioxide gas which expands in the process. Therefore, we can take dry ice, let it sublime into a gas, and use the gas to blow up a balloon. Follow these steps:

  1. Blow up a balloon and tie it off so no air leaks out
  2. Take the lid off the plastic soft drink bottle
  3. Drop a few pellets of dry ice into the plastic bottle
  4. Fit the balloon over the top of the plastic bottle
  5. Notice that the balloon begins to inflate as the dry ice sublimates. You can shake the bottle to make it expand a bit faster (air currents make the dry ice sublimate faster).
  6. Once the balloon is full, tie off then end so no carbon dioxide leaks out
  7. Take the balloon filled with carbon dioxide and the balloon you blew up and drop both at the same time. Note how the balloon filled with carbon dioxide drops faster. That’s because carbon dioxide is heavier than air and more dense. Another interesting aspect of the heavier density of CO2 in the balloon is that it focuses sound and gives an amplification type effect. Speak through the balloon to demonstrate.

Pot of Gold Mini

Parent/Teacher/Advanced Notes

Dry ice pelletsNote: You may have heard of “dry ice bombs”. Placing dry ice in a balloon and placing the balloon on top of some water will cause the balloon to expand and freeze to the water that it was placed on top of. Typically it will pop, especially if someone tries to pick it up. In other demonstrations on the Internet, they may actually place the dry ice in a harder, sealed container such as a plastic bottle or glass bottle. This can be a very dangerous and dumb thing to do. The sound of the explosion can damage ear drums even if you are not close and of course, pieces of debris (i.e. broken plastic or glass) can fly through the air and hit you (or even go through you).

Experiment Supplies

Supplies: Plastic bottle, Balloon, Dry ice


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