This week's experiment is about making dry ice crystal bubbles with a few household items and of course dry ice.
Here's How It Works:
When you drop a piece of dry ice in a bowl of water, the gas that you see is a combination of carbon dioxide and water vapor. So, the gas that you see is actually a cloud of tiny water droplets. The thin layer of soap film stretched across the rim of the bowl traps the expanding cloud to create a giant bubble. When the water gets colder than 50ºF, the dry ice stops making fog, but continues to sublimate and bubble. Just replace the cold water with warm water and you're back in business.
Here's How To Do It: Parental Supervision Advised.
- Mix 2 tablespoons (30 mL) of liquid dish soap with 1 tablespoon (15 mL) of water in a plastic cup.
- Cut a strip of cloth that is about 1" (25 mm) wide and 18" (46 cm) long.
- Soak the strip of cloth in the soapy solution you made in step two. Make sure the entire cloth is submerged in the solution.
- Find a bowl or bucket that has a smooth rim and is smaller than 12" (304 mm) in diameter. You don't need a clear bowl or bucket, but trust us, you'll want one.
- Fill the bowl half full with warm water.
- Using heavy gloves or tongs, transfer two or three pieces of dry ice into the warm water. You don't want too little or too much fog to be produced.
- Dip one or two fingers in the soap solution and run your fingers on the lip of the bowl. (Be careful not to get soap in the water, otherwise you'll end up doing another experiment.)
- Remove the strip of cloth from the soapy solution and run the cloth between your thumb and forefinger to remove excess soap.
- Stretch the cloth between your hands and slowly pull the soapy cloth across the rim of the bowl. The goal is to create a soap film that stretches across the entire bowl.
HINT: Getting the soap film to stretch across the rim of the bowl can take a little practice until you get the technique mastered. If all else fails, try cutting a new strip of cloth from a different type of fabric (try an old t-shirt) or change the soap solution by adding more water or more soap.
- Once you've made the soap film, it will start to expand and fill with the dry ice fog. Once it bulges out, it looks just like a crystal ball.
- When the giant bubble bursts, the cloud of "smoke" falls to the floor, followed by an outburst of ooohs & ahhhs!