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	Dry Ice

For other activities, see the Activities Chapter.

Dry ice is a lot of fun, and can be very educational. A perfect combination!

Dry ice can be obtained from some stores that sell ice. Look them up in the yellow pages.

Dry ice is frozen carbon dioxide. Carbon dioxide makes up 0.03% of the Earth's atmosphere. We exhale it with every breath we take. Plants absorb it and use it in photosynthesis. It is also what makes soft drinks fizz. It is much colder that ice made from water. It is -109.3°F or -78.5°C. This makes it a little dangerous. It is so cold that it can burn your skin. Also, be careful that pieces don't fly into unprotected eyes.

Dry ice doesn't melt like water ice. Water ice goes from a solid to a liquid and then to a gas. Dry ice goes directly from a solid to a gas - a process known as sublimation. Dry ice is also more dense than water ice and sinks when placed in water.

The carbon dioxide gas is heavier than air.

Remember that carbon dioxide does not support life. It could be fatal to babies and pets.

Some things you might want to have on hand to experiment with dry ice are: insulated gloves, safety glasses, hammer, spoon, film canisters, 2-liter plastic bottle with rubber stoppers, cups, newspaper, warm water, balloons, candle with holder, lighter, needle and thread.

Some of the interesting properties that you will want to explore.

• Small chips with flat sides will slide on a cushion of carbon dioxide vapor.
• Place a spoon firmly on a piece and it will sing as the dry ice sublimates.
• Make a pop gun. Place one or more chips in a film canister or 2-liter plastic bottle with some warm water. As the dry ice sublimates, the vapor takes up more volume than the solid so pressure builds and the lid will pop off. Do not point it at anyone. Do not use a screw-on lid as the container may explode. This can also be shown by placing a piece of dry ice in a balloon (hold the opening of the balloon open with your fingers) and tying the end.
• Make a fire extinguisher. Place one or more chips in a cup with a little warm water. As the dry ice sublimates, the carbon dioxide gas builds up in the cup because it is heavier than the air. You can pour the carbon dioxide onto a lit candle to extinguish it.
• Make a witch's brew. Place a bunch of dry ice in a container full of warm water. It will bubble and make fog - just like in the movies. The fog is actually water vapor that condenses because of the cold carbon dioxide gas. The fog will flow over the edges of the container and down onto the table.
• Make a jet engine. Tie a loop in the thread about 4 inches in diameter. Using a needle, poke a hole near the top of a film canister. Make the hole at an angle. Make another hole on the opposite side of the film canister. Place a piece of dry ice in the film canister along with some warm water. Place the loop of thread on top of the film canister and then put on the lid. Hold by the thread. The expanding carbon dioxide vapor will be forced out the pinholes and make the film canister spin.

Other resources and with more exciting experiments:
dryiceInfo.com
The Saturday Scientist
Rock-It Science