Dry Ice Smoke Ring Launcher – SICK Science
Here's how to shoot dry ice vapor rings acres the room using easy to find materials.
You may have heard us use terms like “kitchen science” or “kitchen chemistry” for our activities. That means you can use stuff that’s probably already in your kitchen to perform some really cool science. These Mini-Vapor Ring Launchers are no exception. Everything you need is likely right in your kitchen (and at a local supermarket for dry ice). You’ll be launching rings and putting out candles in no time!
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- Plastic cup(s), 16 oz (473 ml)
- Scissors (or utility knife)
- Heavy plastic bag (freezer type)
- Dry ice (small pieces)
- Water (warm)
- Large coin, 1" (25 mm) diameter
- Marking pen
- Rubber band(s) to fit top of the cup
- Safety goggles
- Adult supervision
Turn the cup over and trace the coin onto the bottom with the pen. Make the circle as close to the center of the cup as possible. Ask an adult for assistance with this part. Using the scissors or the utility knife, cut out the circle you traced on the bottom of the cup. Make the edges as smooth and round as possible.
Lay the plastic bag over the large, open end of the cup. Hold it tightly in place with the rubber bands.
Use the scissors to trim away excess plastic. Be sure to leave enough plastic around the opening to allow you to grab it and pull it snug.
Pour about 2 oz (60 ml) of warm (not hot) water into the cup through the hole you cut in the bottom.
Wear the heavy gloves and drop 1 or 2 pieces of dry ice (small enough to fit through the hole) into the cup. Wait couple of seconds and white vapor begins to belch from the hole!
Hold the cup with one hand so that the plastic wrap is facing you and the hole points away. Tilt the cup a little so the water stays puddled against the plastic. With your other hand or fingers, lightly tap the plastic layer. It may take a little bit of practice, but you’ll be shooting picture perfect vapor rings in no time. In fact, set up a candle across the table from you and shoot vapor rings to put it out. Test to see how far you can be from the candle and still put it out.
How Does It Work
The correct name for your air cannon is “vortex generator.” The ring of air that shoots out of the hole you cut into the cup is actually a flat, rolling vortex of air. A vortex is generated because the air leaving the cup at the center of the hole is traveling faster than the air leaving around the edge of the hole. That speed difference creates a swirling motion or vertical vortex that can be seen rolling through the air if a little vapor is blown out with it. Tapping the plastic on the cup creates the movement of air needed for a vortex to form and the tapered shape of the cup pushes the moving air together.
But where does the vapor come from? When you drop a piece of dry ice into warm water, the gas cloud you see is a combination of carbon dioxide (CO2) and water vapor. So, the gas you see is actually a cloud of tiny water droplets. In many ways, this activity demonstrates that air occupies space… and the flying vapor rings are an added bonus.
Take It Further
How is Dry Ice Made?
The first step in making dry ice is to compress carbon dioxide gas (CO2) until it liquefies while at the same time removing excess heat. The CO2 will liquefy at a pressure of approximately 870 pounds per square inch (4500 cmHg) at room temperature. Once liquid CO2 is formed, the CO2 is sent through an expansion valve and enters a pressure chamber. This pressure change causes the liquid to flash into a solid and causes the temperature to drop quickly. About 46% of the gas will freeze into “dry ice snow.” The rest of the CO2, about 54%, is released into the atmosphere or recovered to be used again. The dry ice snow is collected in a chamber where it is compressed into block, pellet, or rice-sized pieces using hydraulics. It’s complicated but really cool science – really cool.
Can you make your own dry ice? Sure, anything is possible, but it’s not practical (unless you have a huge tank of compressed CO2 sitting around and lots of extra time and equipment on your hands). For around $2 US a pound, it’s hard to beat the convenience of just purchasing it at the store.
NOTE: Whenever you use dry ice, always be aware of the rules for handling it safely.
- This is not a toy. It’s for demonstration purposes only.
- Use dry ice only with adult supervision.
- Dry ice must be handled using heavy gloves or tongs. It will cause severe burns if it comes in contact with bare or unprotected skin.
- Always wear safety goggles when handling dry ice. The debris and shards are extremely dangerous to your eyes. When tapping dry ice with a hammer, first cover it with a towel to keep the pieces in one place.
- Never put dry ice in your mouth.
- Never store dry ice in an airtight container. As the dry ice sublimates, gas pressure will build and the container will explode. Make sure your container is ventilated or has a loose-fitting lid.
- Do not store dry ice in your freezer. It will cause your freezer to become too cold and the freezer may shut off. On the other hand, if you lose power for an extended period, dry ice is a good way to keep things cold if you can get it.
- In the unlikely event of a dry ice burn, treat it the same as you would a heat burn. See a doctor if the skin blisters or comes off. Apply antibiotic ointment to prevent infection and bandage mild burns.
What is dry ice?
Dry ice is not frozen water – it’s frozen carbon dioxide (CO2). Unlike most solids, dry ice does not melt into a liquid as the temperature rises, but instead, changes directly into a gas. This process is called sublimation. The temperature of dry ice is –109.3°F (-78.5°C). Dry ice is particularly useful for keeping things cold because of its temperature. Dry ice does not last very long, however, so it’s important to purchase the dry ice you need for these science activities as close as possible to the time you need it. The best place to store dry ice is in a Styrofoam ice chest with a loose fitting lid that allows the CO2 to escape as the ice sublimates.
Some grocery stores and ice companies will sell dry ice to the public especially around Halloween. Dry ice is typically sold as flat, square slabs a few inches thick or as cylinders that are about three inches long and about a half-inch thick. Either size will work fine for these experiments.
Remember the science when purchasing dry ice. Dry ice in a grocery bag will vanish in about a day. The experts tell us that, depending on weather conditions, dry ice will sublimate at a rate of 5 to 10 pounds (2.3 to 4.5 kg) every 24 hours even in a typical Styrofoam chest. So, again, it’s best to purchase the dry ice as close to the time you need it as possible. Last minute shopping is necessary. If you are planning to perform a number of dry ice demonstrations or have a lot of people involved, purchase 5 to 10 pounds (2.3 to 4.5 kg). A little dry ice does go a long way in these activities.