Monday, May 6, 2013

Fun with dry ice

Let's face it, dry ice is fun. A super cold solid form of carbon dioxide, dry ice sublimates at room temperature, creating an eerie fog. Not only is dry ice great for science experiments, it's fun for parties too.

Luckily it's not that hard to get either. I have a local distributor called The Ice Factory, where I can drive right up and ask for a 30 lb. block any day of the week. You need to bring a cooler with you, or your frozen treasure won't last very long. A good pair of work gloves are needed to allow you to handle the stuff. I often ask to have it pelleted, for ease of use. But, as you'll see below, a big block of dry ice can be a lot of fun too.

So what do you do with your dry ice, once you've got it at home? I like to let kids explore the pellets alone first, observing the fog and talking about what's happening. Then we add warm water. The warmer the water, the more fog you get, because the difference in temperature affects the rate of sublimation. If you use a large clear container, kids can also see the bubbling as gas is generated. A little food coloring helps.

Then I like to add some dish soap. Suddenly everything changes, and big cloudy bubbles emerge from the container. Popping them releases the fog held inside. It's a ton of fun. Again add a bit of food coloring for added excitement.

Later, when all the dry ice is gone, the frothy, frozen soap will be left behind. It's lots of fun to play with too!

Remember how I said I like to get a big block of dry ice as well? If you use a power drill to add a wide hole to the top of the block and smaller ones to the sides, you can create a really amazing demonstration. You'll need magnesium ribbon as well.

Magnesium is a common alkaline earth metal. It's highly reactive and burns readily, producing a bright white light. Which is pretty cool all by itself, right?

When you place the magnesium ribbon in the dry ice and light it, things get dramatic. The burning magnesium can seal oxygen from the carbon dioxide in the dry ice, burning brightly without the need for other oxygen. In turn, the exothermic reaction speeds the sublimation of the dry ice, resulting in even more fog. The science is fun, but the visual is even better!

If you decide to try this at home, be sure to do it outdoors, or in a well ventilated area. And be sure to remove flammable items. This can get hot and bits of magnesium can be thrown off.

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