Learning about sublimation: 5 easy dry ice experiments your kids will love.
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This summer my kids got a great introduction to sublimation through five easy experiments we conducting using dry ice, otherwise known as frozen carbon dioxide.
SAFETY NOTE: Dry ice should not be handled by children. Adults should always use insulated gloves, oven mitts, or tongs when handling dry ice to prevent frostbite or severe burns. Dry ice should also be handled in well ventilated areas, since it can lower oxygen levels (you’ll notice that all of our experiments took place outside). Visit this site for more dry ice safety information, and please use your own best judgement and common sense.
Learning About Sublimation with 5 Easy Dry Ice Experiments
Kids love seeing these five simple dry ice experiments! One of them is even edible. Remember, these are adult demonstration experiments – not something for kids to do on their own.
Dry Ice Experiment #1: Does Dry Ice Melt?
This first experiment is very simple! Put some dry ice on a tray or on the ground or even in a bag, and watch what happens. Most kids will predict that the ice will melt like any other ice, but dry ice evaporates! This is because dry ice sublimates – it moves directly from being a solid to a gas. This experiment is especially magical in a plastic bag, since you just end up with an empty bag (full of carbon dioxide, but you can’t see that with your eyes) at the end.
Dry Ice Experiment #2: What Happens When you Put Dry Ice in Water?
My kids LOVED this experiment! We filled our sand table (which we use as a sensory table) with water (cold or room temperature). I then added a few pieces of dry ice. Water is a much better heat conductor than air (think how much colder 60 degree water feels compared to 60 degree air), so the dry ice sublimates more quickly. As the frozen carbon dioxide turns into a gas, the gas bubbles up to the surface for a very fun visual effect!
Dry Ice Experiment #3: What Happens When You Put Dry Ice in a Toy Tea Kettle?
Take a toy tea kettle and add a little water and a small piece of dry ice. As the dry ice sublimates into a gas, you see “steam” coming out of the spout. The pressure may grow high enough to begin to life the head as well!
This experiment is a great demonstration of why you don’t want dry ice mixed with a liquid inside a sealed container unless you have a pressure safety valve to keep the pressure within safe levels (more on this later).
The cold water here is a a safety factor. Dry ice in hot water can sometimes create splashes of hot water and burns.
Dry Ice Experiment #4: What Happens When You Place a Container Full of Dry Ice Inside a Container of Water?
In this experiment, the coolness of the toy kettle causes little bits of ice to form in the plain water around the outside of the kettle. The bubbling of the frozen carbon dioxide prevents this same thing from happening on the inside of the kettle. You can see some of these bits of ice floating on the top of the photo below, taken after we dumped the water plus dry ice mixture from the kettle into the sensory table.
Dry Ice Experiment #5: What happens when you put dry ice in your drink?
Put a few small chunks into your drink, and watch what happens:
The carbon dioxide sublimates in the drink just as it did in the water. In the process, it leaves your drink very mildly carbonated.
SAFETY NOTE: This is safe to drink, so long as you make sure that there are no pieces of dry ice left in the drink. NEVER drink or eat solid dry ice.
You CAN make properly carbonated soda this way, but you need a seal with a pressure safety valve to prevent an explosion. Remember how the pressure of the dry ice in the toy kettle was strong enough to lift the lid? We didn’t have a safety valve AND I am not anywhere an expert on this so we didn’t try it. My kids and I also don’t like heavily carbonated drinks, so this was perfect for us.
Once you have finished these experiments, be sure to try making dry ice ice cream!