Dry Ice Crystal Ball Bubble It's the world's coolest crystal ball. email to friend
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Great Halloween Science It's the world's coolest crystal ball. Create a soap film on the rim of the bucket and you'll have what appears to be a crystal ball filled with a cloud-like mixture of water vapor and carbon dioxide. When the giant bubble bursts, the cloud of "smoke" falls to the floor followed by an outburst of ooohs & ahhhs from your audience!

Materials

Large bucket with a smooth rim
Solution of dish soap and water
A piece of cloth 18 inches long, gloves, safety glasses
A few pieces of dry ice

Dry Ice - Grocery stores use dry ice to keep food cold during shipping. Some grocery stores and ice cream shops will sell dry ice to the public (especially around Halloween) for approximately $1 per pound. It's a good idea to take a beverage cooler with you along with a pair of gloves to protect your hands. If you are planning to perform a number of dry ice demonstrations, plan to purchase 5 to 10 pounds.

Experiment
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Select a bucket or container that has a smooth rim and is smaller than 12 inches in diameter. Cut a strip of cloth about 1 inch wide and 18 inches long. An old t-shirt works well. Soak the cloth in a solution of Dawn dish soap or use your favorite recipe for making bubble solution. Make sure that the cloth is completely soaked. Fill the bucket half full with water. Have tongs or gloves ready to transfer the dry ice to the bucket.

Place two or three pieces of dry ice into the water so that a good amount of fog is being produced. Remove the strip of cloth from the dish soap and carefully pull the strip across the rim. The goal is to create a soap film that covers the top. It also helps to have the rim wet before you start. This may take some practice until you get the technique mastered. Remember that a bubble's worst enemies are dirt, oil, and rough edges. Your patience will pay off in the long run. If you accidentally get soap in the bucket of water, you'll notice that zillions of bubbles filled with fog will start to emerge from the bucket. This, too, produces a great effect. Place a waterproof flashlight in the bucket along with the dry ice so that the light shines up through the fog. Draw the cloth across the rim to create the soap film lid and turn off the room lights. The crystal bubbles will emit an eerie glow and you'll be able to see the fog churning inside the transparent bubble walls. Take your bows as the class erupts in a chorus of ooohs & ahhhs!

Additional Info

Bob Becker presented this activity during a lecture at the National Hands- on Science Institute (www.nhosi.com) in Denver in 1997. Bob is a chemistry teacher from Kirkwood, Missouri, who constantly searches for new ways to turn students onto the wonders of science.