Dry Ice Experiments

Erin Coleman, R.D., L.D.
dry ice

Dry ice is carbon dioxide in frozen form, with a temperature of about negative 109 degrees Fahrenheit. Unlike regular ice, dry ice doesn't melt into a liquid. Instead, when dry ice melts, it turns into a gas. So when you see dry ice "smoking," it's frozen carbon dioxide melting into its gaseous state. Dry ice is a popular ingredient in science experiments and for a good reason. It's versatile and creates projects that look cool. The number of experiments you can perform using dry ice is endless, which is why choosing just one will be your biggest challenge.

Experiment #1: Healthy Dry Ice Yogurt Popsicles

This dry ice experiment is a simple project, but it's certainly a showstopper. It has appeal to a wide range of audiences, but even kids as young as five will at least appreciate the observations. It should take you about 10 minutes or less to have a frozen treat to enjoy.

Materials

  • One large slab of dry ice
  • Large spoon or tube-shaped piece of metal
  • Four Popsicle sticks
  • One cup of your favorite juice
  • Tall glass filled with water

Directions

  1. Using the large spoon, or tube-shaped piece of metal (i.e., like the handle of a pastry blender or similar) make a Popsicle-shaped indentation in a slab of dry ice. You can set the ice on a towel on your counter to do this work. Of course, keep in mind that it's okay if it's not exactly Popsicle-shaped.
  2. Add a Popsicle stick to the middle of the indentation so that when you pour in the liquid, it will freeze around the Popsicle stick.
  3. Hold the Popsicle stick in place and wait a few minutes for your Popsicle to harden.
  4. After several minutes, remove the Popsicle from the slab of dry ice and dip it into a tall glass of water. Do this to warm up the Popsicle just a bit first. Otherwise, it will be too cold.

Below is a video that demonstrates the process.

Insulation Variation

Now think! Is there anything you can add to insulate your Popsicle so that it wouldn't freeze as easily.

  1. Follow the instructions above, and make an indent in the ice.
  2. Now, instead of a large plastic bag (a half gallon), add about a cup of shortening. You want the walls of the large plastic bag to be thick with this natural insulator.
  3. Use a smaller plastic bag (sandwich sized) and pour some juice into that bag. Zip it closed and then add it right to the middle of the blubber.
  4. Follow the same procedure as above - how long does it take the Popsicle to freeze now?

Ingredients Variation

Juice pops aren't the only thing you can make. Try these combinations and see if it takes longer to freeze!

  • Blend one cup of vanilla yogurt and one-fourth cup of fruit.
  • Blend heavy cream, vanilla and chocolate and follow the same directions for freezing. Don't forget to dip the Popsicles in the water before continuing.

Does the Popsicle with the higher fat content take longer?

Experiment #2: Dry Ice Balloon

This experiment will blow your mind, and help you amaze science fair competitors. It's most appropriate for kids, grades third and up and will take only a few minutes to perform.

Materials

  • Empty plastic bottle
  • Warm water (enough to fill your bottle 1/3 full)
  • Your favorite food coloring
  • Three pieces of dry ice
  • Two round balloons
  • Insulated gloves
  • Safety glasses

Directions

  1. Put on your gloves and safety glasses.
  2. Place warm water in the plastic bottle.
  3. You can mix in food coloring if you want.
  4. Place dry ice in the plastic bottle.
  5. Watch the dry ice bubble in the water and wait about 10 seconds.
  6. Place a round balloon over the mouth of the bottle (as the video indicates).
  7. Watch the balloon inflate as frozen carbon dioxide melts into its vapor form.
  8. Tie off the balloon.
  9. Before you move onto the variations, take some time to experiment with your dry ice balloon. Does it seem more or less buoyant balloon blown up with regular air (with your mouth)?

Variation

Now that you have the basic procedure down, grab a second balloon. Blow this one up with your mouth. Now compare the balloons - which one is heavier? Which one seems to float? If you want, fill a third balloon with helium and compare the three balloons.

Experiment #3: Dry Ice Candles

Did you know that carbon dioxide released by dry ice can actually put out flames? Wow your peers with this (mostly) effortless experiment. It's appropriate for young kids, grades first and up - so long as there is plenty of adult supervision. The experiment takes no longer that five to ten minutes depending on how many candles you're blowing out.

Materials

  • Three Candles
  • Lighter
  • Glass or bowl (an aquarium or a similar type of container works well)
  • One-half cup of water
  • A chunk of dry ice (the size does not matter
  • Dry ice gloves

Instructions

  1. Light the candles with a lighter.
  2. Put on your gloves.
  3. Pour one-half cup of water into a glass or bowl.
  4. Place a piece of dry ice into the glass or bowl with water, and watch the dry ice vapor begin to rise.

What's Happening

When you add dry ice to water, it produces carbon dioxide - the gaseous form of dry ice. Since flames need oxygen to burn, the flames go out once the oxygen is taken over by dry ice.

Safe Handling Instructions

Because dry ice is so cold, it isn't safe to touch it to your skin or put it in your mouth. Always use insulated gloves or thongs when handling dry ice to avoid frost bite and other injuries to your skin. If you put dry ice into a bottle, avoid capping the bottle as the pressure from dry ice can push the cover off forcefully. And of course, never handle dry ice unless supervised by an adult.

Dry Ice Experiments