Dry ice is extremely cold, plus it's also cool! There are lots of interesting experiments and projects you can try using dry ice. For example...
If you don't have dry ice, the first cool thing to do is to make some yourself!
One of the simplest, yet still coolest things to do with dry ice is to toss a chunk of it into a container of hot water. This causes the dry ice to sublimate (turn into vapor) more quickly, producing dry ice fog. This is a popular party effect. It's even more spectacular if you have a lot of dry ice and a lot of water, such as dry ice in a hot tub.
Place a piece of dry ice in a bowl or cup containing bubble solution. Wet a towel with bubble solution and pull it across the lip of the bowl, trapping the carbon dioxide into a giant bubble that resembles a crystal ball.
Freeze a soap bubble over a piece of dry ice. The bubble will appear to float in the air over the dry ice. You can pick the bubble up and examine it.
Inflate a Balloon with Dry IceSeal a small piece of dry ice inside a balloon. As the dry ice sublimates, the balloon will blow up. If you use too big a piece of dry ice, the balloon will pop!
Inflate a Glove with Dry IceSimilarly, you can put a piece of dry ice into a latex or other plastic glove and tie it closed. The dry ice will inflate the glove.
Simulate a Comet
You can use simple materials to simulate a comet. In a big plastic bowl, lined with a trash bag, mix together:
1 liter water 2 cups dirt 1 tablespoon starch (holds comet together, not found in real comets) 1 tablespoon syrup (comet organic component) 1 tablespoon vinegar (for amino acids) 1 tablespoon rubbing alcohol (like the methanol in real comets)
Put on gloves and add 5 pounds of roughly crushed dry ice. Feel free to add a little more water. Press together the ingredients in the plastic trash bag. You can dust your finished comet with dirt, since most comets are dark objects. Like a real comet, your model will shoot off jets of gas and will have a similar composition to the real deal. You can find more information at NASA's Jet Propulsion Lab
Sealing dry ice into a container will cause it to burst. The safest version of this is to place a small piece of dry ice into a plastic film canister or potato chip can with a pop lid.
While you can't eat dry ice, you can use it as a decoration for food. In this project, dry ice produces a volcanic eruption for a volcano cake.
Make a cool Halloween jack-o'-lantern that spews dry ice fog.