Now I get to tell you about one of my personal favorite dry ice experiments. It’s so much fun, you’ll want to do it twice. By doing it the first time as an observation and the second time as a measurement you get two fun dry ice experiments for the price of one.
Here’s what you’ll need:
2 small cups (In a science class, I used 100 ml beakers. If you are using larger cups you will want to increase the amount of water and soap.)
6 drops of dishwashing detergent for each cup
About 10 ml (or 3 TBS) each of hot and cold water
Stirrer to stir the soap and water
2 similar sized pieces of dry ice
Here’s what you do:
Write question, “How does temperature affect how fast dry ice turns into a gas?”
Write down what you think the answer will be and why. (Call this your hypothesis.")
Add the soap to each cup.
Add hot or cold water to each cup.
Add the dry ice to each cup.
Record your observations.
Pretty cool right?
It gets even better, because now you have something you can measure.
Now repeat the dry ice experiment you’ve already done, but this time, measure how fast the dry ice is sublimating.
Now, it is very easy to create fun dry ice experiments to see what factors other than temperature might affect the rate of sublimation of dry ice.
Alternately, you can experiment to see how to make a soap solution that will create more bubbles. What is the best ratio of soap to water? Will adding a drop of glycerin effect the outcome? Which brands of soap work best? How about using laundry detergent or shampoo? Even if New York cleaning service workers won't consider cleaning with soaps like these, laundry detergent and shampoo will make an interesting change in your science experiment.
You get the idea.
Other fun ways to measure the speed of sublimation
There are three other ways to measure the speed of sublimation:
If you put dry ice into a bottle and cover the bottle with a balloon, the balloon will blow up. You can measure how quickly the balloon expands. Because this doesn’t require adding water to the dry ice, this is a good way to see how water effects the rate of sublimation.
You can make a dry ice rocket by using a film canister. Put the dry ice in the canister, and then turn the canister upside down, stand back, and watch what happens. You can also add water by putting water in the canister, and keeping the dry ice in the lip until you close it. (This same technique also works for making a film canister rocket with alka seltzer.)
You can put the dry ice into a larger container, with a candle inside the container. As the container fills with carbon dioxide, the candle will be extinguished. By measuring how long it takes for the candle to go out, you can measure how fast the dry ice is sublimating.