Dry ice offers the opportunity for lots of science fun with kids of all ages! There will be lots of ooohs and aaahs and giggles! But, there are some safety precautions to be aware of, so these all require adult supervision. This tutorial will give you several ideas on how to demo this for kids from preschool to grade school on up, whether in a science class, home school setting, birthday party, or just for a fun parent-kid activity.
How to get and store dry ice
You can get it at many grocery stores, or it may come with grocery deliveries or meal delivery services you use. Plan to get it as close in time as possible to when you plan to use it. In 24 hours, a ten pound block of dry ice can sublimate completely – change to gas and disappear. You don’t need a lot – a 4 x 4 inch square was plenty for us each time we’ve done this. Store it in an insulated foam container. Keep the container in a well-ventilated area. (For example, if you’re driving with it in your car, roll down the windows – it is off-gassing carbon dioxide which can cause rapid breathing, headaches, or worse.) For more info, read this wikihow on How to Buy Dry Ice or read info on Steve Spangler Science page.
Never touch dry ice with bare hands!!! It is very cold (-109°F) and can “burn” your skin. Use tongs or insulated gloves whenever handling it and treat it with as much respect as you would a hot frying pan. If you want to break apart some dry ice, always cover it with a towel first, so no shards can fly up at your face. (And use safety goggles, just in case.) Never put it inside a tightly sealed container. As the gas sublimates, pressure builds and the container could explode. Always use in well-ventilated areas. (See the wikihow or Steve Spangler articles cited above for more info.)
Experiments to Try
There are lots of activity ideas here. Do whichever ones inspire you. I’ll give you some of the scientific explanations below, so you can share them with your kids / students. But let the focus of all this be on the fun, and the “magic”, spend plenty of time playing and oohing and aahing before you feel like you need to “teach” anything.
Note: Whenever I say “a small piece” of ice, I’m talking the size of a regular ice cube or smaller.
- Why it’s called dry ice: Put a small piece of dry ice on one plate, and a regular ice cube on another plate. Leave it alone for 30 – 60 minutes, then notice that the dry ice plate is dry and empty. The regular ice plate has a small puddle of water. Explain that the ice was solid water, which turned to liquid water when it got warmer. If we heated it more, it would turn to gas water (steam.) Explain that dry ice (carbon dioxide) is different than many other substances. When dry ice gets warm, it sublimates instead of melting… instead of becoming a liquid then a gas, it goes directly from solid to gas and vanishes into thin air.
- Making fog: Take a container of warm water. Drop in a small piece of dry ice. Fog will form. (This isn’t smoke. It isn’t steam. It’s a combination of carbon dioxide gas from the dry ice, and tiny water droplets.)
- Blow up a balloon: Fill a bottle halfway with warm water, drop in a small piece of dry ice, and put a balloon on the mouth of the bottle. Watch the gas blow up the balloon. (Note: remove the balloon before it gets full enough to pop!) This demo is a nice clear illustration that gas is escaping.
- Floating bubbles: Fill a bowl with water, drop in a piece of dry ice. When a cloud of fog forms on the water, blow bubbles and let them land on the fog – they will float there. The dry ice fog is heavier (denser) than air, so it sinks down. But it’s less dense than water, so it floats on the water. The bubbles are heavier than air, but less dense than carbon dioxide fog, so they’ll float on the fog.
- Bubbles of fog: Fill a bowl with a little warm water. Stir in some dish detergent (or bubble solution). Drop in a piece of dry ice. A cloud of fog-filled bubbles will boil up out of the bowl. Kids love popping these bubbles and releasing a poof of “smoke.”
- Bubble prints. Once you have a bowl of foggy bubbles, drop some food coloring onto the bubbles. Then place paper carefully on top, and press down ever so gently. Peel it off carefully, and you’ll have bubble art. (See pictures on Science Kiddo.)
- Water droplets: Put dry ice in a tray, let kids drop water on it – the water beads up and rolls off. After you’ve done this for a while, use the tongs to flip the ice over. A layer of colored water is frozen along the bottom.
- The fountain: Test your water bottle or sippy cup… does water pass through the straw very easily? (You never want to put dry ice in a tightly sealed container because pressure will build up quickly and it can explode.) Put some water in the sippy cup or water bottle / drop in a small piece of dry ice and screw on the lid – the water will fountain up out of the cup. (See video at the top of this post.)
- Fountain of bubbles. Repeat that experiment, except add a little detergent or bubble solution to the water before you add the dry ice… here’s a video where we didn’t get the lid back on before all the bubbles started erupting.
- Fire. Put water in a container, add the dry ice to make some fog. Light a match or a candle – hold it in the fog. The fire will go out. Carbon dioxide is a fire suppressant – fire needs oxygen to burn.
These activities could be done in a States of Matter unit, or as a stand-alone activity.