This is a fun science project using Co2 or dry ice.
Co2 is maybe one of many most fascinating compounds in the world. Both in science, and everyday use. I recently published an article on using Co2 to freeze beer, which got me started on this article. Before you begin, you will need some basic knowledge about Co2:
- Co2 is about 1.5 times heavier than air.This is why you’ll see it swirling around on the ground at a rock concert
- Co2 can take on the form of solid, liquid, or gas.
- Co2 is EXTREMELY COLD (about -109 F or -78 C) and gloves must be worn to handle it.
- Co2 will produce great pressures: 850 to 900 psi @ 75 to 80 Degrees F
- Co2 in large volumes can (in a closed room) cause respiratory distress, and should be handled with adequate ventilation.
Now that we have some basic facts, here is what you will need:
- A 50 pound block of dry ice (a smaller block does not last as long)
- Several plastic containers ( 2 liter plastic bottles, plastic milk jugs, any PLASTIC container with a lid)
- A roll or two of Teflon tape.
- Safety glasses or goggles
The containers you choose for this project should ONLY BE PLASTIC, and should have tight fitting, screw on type caps. Once you have chosen your containers, you will need to Teflon tape the threads to make sure you have a tight seal. Tip: When applying Teflon tape wrap the threads of the container clockwise, no more than two complete wraps.
Now that you have your containers ready (You generally can’t reuse them), you will need some dry ice. Usually most compressed gas companies and some welding supply companies carry it. When transporting your dry ice DO NOT put it in a tight fitting cooler. And DO NOT put dry ice in your freezer (even at 32 degrees F Co2 is still about 300psi, and will most likely blow the door open – or off!) A block of dry ice will usually last a few hours in a thick wall Styrofoam cooler, provided it is not too hot outside. Unlike ice cubes, dry ice does not “melt;” it evaporates and gets smaller.
Now the fun part: Wearing gloves AND safety glasses, use a flat screwdriver or chisel to chip some pieces small enough to fit down the neck of your 2 liter plastic bottle. About 8 to 10 ounces of dry ice should be enough. Once you have the dry ice in the bottle, IMMEDIATELY screw the cap on (POINT IT AWAY FROM YOUR FACE).
Place the container outside in an open area (a large yard or field). Get back at least 20 feet and wait. You will see one of a few results. Either the cap will blow off straight up in their like a rocket, or the plastic bottle will expand sometimes twice its size. DO NOT get close to the container until it has exploded.
You can try some variations here, such as adding more dry ice, and a few ounces of water, however water speeds up the evaporation process, so you have less time to get out of the way.
You can also experiment with wide mouth plastic containers, as they are easier to put the dry ice in. Remember safety first, have fun.
This is only intended as a science project, and misuse is the sole responsibility of the user.
Some things of note: The cause of the pressure build up is the dry ice trying to change states from solid to gas, to liquid. If the dry ice were to be refrigerated to 32 degrees F, it would pressurize to 300psi. If the dry ice were exposed to heat above 75 to 80 degrees F, the pressure would start to increase to over 1000psi! The more heat, the more pressure.