How To Make a Dry Ice Balloon

Sublimation of Dry Ice Blows Up a Balloon

Carbon dioxide is heavier than air, so dry ice balloons will rest on a surface rather than float.
Carbon dioxide is heavier than air, so dry ice balloons will rest on a surface rather than float. Fuse, Getty Images

You usually blow up balloons with air or helium, but did you know you can get a balloon to inflate itself using dry ice? Here's how you perform this simple science project:

Dry Ice Balloon Materials

  • Balloons
  • Dry Ice Pellets
  • Funnel (optional)

It's easiest to work with a funnel because it holds the neck of the balloon open. If you are working with dry ice pellets, you may find it easier to break or crush them so you can pour them into the balloon.

However, if you wear gloves, it's pretty simple to do this project with just your hands and a balloon. If you have a carbon dioxide fire extinguisher, you can even make the dry ice yourself.

What You Do

  1. Hold open the mouth of the balloon.
  2. Place or pour dry ice into the balloon.
  3. Tie off the balloon so that the gas won't escape.
  4. The balloon will inflate as you watch. You'll see water freeze on the outside of the balloon where the dry ice is cooling the air across the surface of the latex. How much the balloon inflates depends on how much dry ice you added. A small amount of dry ice will slightly inflate the balloon, while a large amount ultimately will make it pop.

How It Works

Dry ice is the solid form of carbon dioxide. At normal atmospheric pressure, dry ice sublimates from a solid directly into a gas. As the gas warms, it expands. Carbon dioxide is more dense than air, so if you drop a dry ice balloon, it will fall to the ground rather than float like a helium balloon.

Dry Ice Safety

Dry ice is cold enough that it can give you frostbite after a very brief exposure. It's best to wear gloves for this project and to let the balloon inflate on a countertop and not in your hand. Also, don't eat the dry ice. Keep it away from children and pets.