Have you ever seen what looked like fog or smoke floating around the stage during a concert or theater performance? If so, then you already know a bit about dry ice. Dry ice is often used in special machines to create the illusion of smoke or fog.

But what exactly is dry ice? And is it really dry? You might be surprised to learn that it’s not really “ice” at all…or at least not what we normally think of as ice. And it IS indeed dry.

Regular ice is frozen water. When it gets warm, it melts and turns from solid ice back into liquid water. If you leave an ice cube out on the counter and come back a while later, you’ll find a wet puddle where the ice cube used to be.

Dry ice, on the other hand, is frozen carbon dioxide. Carbon dioxide is a gas. Each time you breathe, you breathe in oxygen and breathe out carbon dioxide.

Carbon dioxide gas turns to dry ice when the temperature drops to -110° F. That’s right! 110 degrees BELOW zero!

When dry ice is warmed above -110° F, it changes from solid dry ice straight back to carbon dioxide gas. Since it never passes through the liquid phase, it’s called dry ice. If you leave dry ice out in the sun for a few minutes, you won’t return to find a puddle. It just evaporates right into the air!

The scientific process of changing directly from a solid to a gas is called sublimation. One pound of dry ice will produce about 250 liters of carbon dioxide gas through sublimation. That’s enough gas to fill 125 2-liter bottles!

Dry ice has many uses. Because of its cold temperature and the fact that it will not make a mess when it “melts,” dry ice is often used to preserve frozen foods when refrigerators are unavailable or impractical. It can also be used to flash freeze foods.

When dry ice is put in water, the sublimation process gets faster, creating dense clouds of smoke-like fog. Fog machines, theaters, haunted houses and nightclubs regularly use dry ice to create dense fog effects.

Because dry ice is extremely cold, you must use special care when handling it. Tongs or gloves should always be used, since direct skin contact with dry ice can easily cause frostbite.

It’s also important never to use dry ice in a small, enclosed space. Carbon dioxide is denser than oxygen, so when dry ice begins the process of sublimation, the carbon dioxide gas it creates will push away oxygen. In a small, enclosed space, this could result in suffocation.

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    • That sounds like a really “COOL” restaurant, Destiny! What kind of dessert was it? Because dry ice can be extremely dangerous if not handled properly (you should always wear gloves and use tongs to handle dry ice and it should NEVER be eaten), we hope the dry ice that the restaurant used was only for decoration or for a special effect! Thanks for visiting Wonderopolis today and for your awesome comment! :-)

  1. Happy Birthday Destiny-what a great text to self connection with the dry ice and your birthday. I remember when I was in school we used dry ice while reading poetry to create smoke coming out of a black cauldron around Halloween. It was so much fun!

    • Thanks for sharing such a great memory from when you were younger, Maria! Sounds like you had a teacher that inspired Wonder in you just like you inspire it in your own students today! :-)

  2. Ok, That was the COOLEST thing I have ever seen. I thought that dry ice was just ice that was dry, and that when the cold ice out of the freezer sticks to your hands, it is dry ice. Now I really want to go to the store and try that experiment at home. I can now think of many different experiments besides the ones given at the top. Hmmm. I think that tomorrow’s wonder could be about 2012 and how people think that the world is going to end, maybe??

    • Hi, Meredith! We’re so excited that you liked this Wonder of the Day! Let us know how your experiments go, and PLEASE remember to have a grown-up help you with the dry ice! :-)

  3. I am sure you could do some wonderful experiments Meredith at your house. Imagine the predictions you could make with how long the dry ice would last or maybe write a story about a foggy night and use the dry ice as a back drop while reading the story to your family. Just wonder about the possibilities! Check your family email in the next few days I have some very exciting WONDER news that I am going to send to the class!!

    • You’re right about that, Lauren! We thought the bubble was going to POP and shoot the fog in all directions…but it was really neat how it floated down around the bowl! It almost looked spooky! Thanks for letting us know you liked this Wonder! :-)

    • That’s a GREAT question, Lauren! Wonderopolis is a place that exists in our imagination AND in the real world around us! It’s a place to ask questions (we LOVE wondering around here in case you couldn’t tell!), share, grow and learn! Every day, there is a new Wonder of the Day to explore together. We hope you invite your family and friends to learn right along with you…Wonderopolis is for everyone! We hope you have fun visiting Wonderopolis.org every day!

  4. the reason i got on here is my mom is a principal and since we are out of school and we have summer break my mom wanted me to see if this is something the kids at my school would like and i totally enjoy it and so next school year this is a thing my school will be on a lot.

    • We’re so glad you enjoy visiting Wonderopolis and learning new things from the Wonders of the Day, Lauren! We are also very excited that you are going to share Wonderopolis with teachers and other students at your school next year! You are a GREAT Wonder Friend! :-)

  5. This is a great article. It has great information. The detail about how much the dry ice expands in to co2 gas is great and not something you find everywhere. Great job. I think this will be very helpful.

    • Hello, Rashell! We hope you learned some new things about dry ice by exploring this Wonder of the Day®! Sometimes, if our Wonder Friends have a little trouble understanding something they read in one of the Wonders of the Day, they find it helpful to ask a parent or teacher to explain it better. We hope you have a WONDERful day! :-)

    • Great Wonders, FES Second Graders! We Wonder if you have ever received a package in the mail… but not just any package, perhaps it’s a package of ICE CREAM! YUM! In order to keep that ice cream nice and chilly, dry ice is often used. Dry ice doesn’t melt like regular ice, so it’s often used to transport things that need to stay cold. Dry ice can only be used for special purposes, as is can be dangerous if it’s not used correctly. Safety first, Wonder Friends! :)

    • Hi Jace! We learned in the wonder that it’s dry, but not really ice at all! Pretty cool and WONDERful stuff! Thanks so much for WONDERing with us! :)

  6. What does 1lb of dry convert to weight wise. For example 1 lb of dry ice equals. 75 tons of co2 gas. Just trying to visualize my carbon footprint.

    • That’s a great question, joe! We love that you made a connection to this WONDER. Thanks for visiting us at WONDERopolis today! :)

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Have you ever wondered…

  • Is dry ice really dry?
  • What is sublimation?
  • How is dry ice used?

Wonder Gallery

frozen carbon dioxide_shutterstock_41372605Vimeo Video

Try It Out

Still a bit foggy on the facts when it comes to dry ice? That’s cool. Check out the following fun activities with a friend or family member and you’ll pump up your science IQ in no time!

  • Have you ever noticed fog effects in television shows and movies? Isn’t it cool to know that those effects are usually created with dry ice? Search through your collection of movies and television shows — or just flip through the channels on your television randomly — to search for some good examples of fog effects. Isn’t it impressive how the sublimation of dry ice can mimic real fog, smoke and clouds?
  • Are you familiar with the three states of matter? To better understand the WONDER of how dry ice goes directly from a solid to a gas, do a few fun experiments at home with water. Pour a glass of water from the tap into a clear glass. You’re quite familiar with liquid water already. See what happens when you turn it into a solid by freezing it. Pour some liquid water into an ice cube tray and put it in the freezer. Check on it later after it’s frozen. Reverse the process by putting some ice cubes into a cup and letting them thaw on the kitchen counter. To experiment with water turning from a liquid into a gas, ask an adult to help you boil some water on the stove. Do you see that steam rising from the pot? That’s water vapor, the gaseous form of water!
  • Up for a challenge? Why not try some fun science experiments with dry ice? Grab a cooler and head to your local grocery store. If they don’t have dry ice, you might need to look online to find a local store that sells dry ice. Since dry ice is extremely cold, an adult needs to help with these experiments. Make sure everyone uses gloves or tongs to handle the dry ice. Never touch it with bare hands! Choose one of the fun experiments below, get your supplies together and prepare for some foggy fun!

Still Wondering

Check out this Cool Idea from Science NetLinks to see what happens to water and ice when a little salt gets thrown into the mix.


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