Dry Ice Lab Kinetic theory and Phase Changes

Warning! Dry Ice, if kept in confined areas, may cause an explosive rupture of its container

Materials needed for all experiments Dry ice Film Canisters Blue Food coloring Karo Syrup Tongs Goggles Balloons Empty plastic water/soda bottles Straight pins Spoons

Storing and Transporting Dry Ice Dry ice continuously sublimates as heat enters it from its surroundings. The CO 2 gas that evolves must be vented from the container. Do not seal dry ice into a container except as detailed below, because an explosive bursting of the container can result. A Styrofoam (polystyrene foam) ice chest with a loose fitting lid makes a good container for transporting dry ice.

Handling Dry Ice Due to its extremely cold temperature (-78.5 o C, or o F), dry ice can cause damage to the skin if handled. Use tongs or insulating gloves when handling dry ice. It is also important when crushing or grinding the solid not to get any of the dust into your eyes. Wear protective goggles.

To make a bubbling “chemical “ mixture It's simple to create amazing effects using dry ice. At left is a plastic jar of water with blue food coloring and a piece of dry ice. The thick blue substance at the bottom is clear Kraft™ Karo Syrup™, which is denser than water, so it sinks to the bottom, encasing the dry ice. As the dry ice sublimates, [see below for definition of sublimation] it creates interesting, mysterious blue bubbles in the syrup and water, along with fog spilling out over the jar.

Popping film Cans A fun (and often wild) activity vividly demonstrates the sublimation process. Place a piece of dry ice into a plastic 35mm film container - the kind that has the snap - on cap. Then wait. The cap will pop off, and sometimes fly several meters. The clear Fuji brand containers shoot farther than the gray and black Kodak type. Warn anyone performing this experiment not to aim for anyone's eyes.

Question Why does the top fly off Sublimation of the dry ice Creates increased gas pressure

Blow up a balloon using dry ice! How could something as cold as dry ice blow up a balloon?

Why does it do this? Remember that dry ice expands as into carbon dioxide gas when it sublimates. This experiment shows you how that works.

What you need for this experiment: Balloons with openings large enough to fit a plastic bottle opening Empty plastic soft drink bottle Small pieces or large pellets of dry ice Tongs to hold the dry ice Two people

What to Do: 1.Blow up one of the balloons and tie it off. 2.Save the balloon for later. 3.Remove the lid of the plastic bottle. 4.Have one person hold the plastic bottle upright. 5.Using tongs and wearing insulated gloves, take a few small pieces of dry ice and put them into the plastic bottle. 6.Fit a balloon over the opening of the bottle. 7.Watch the balloon inflate with carbon dioxide as the dry ice sublimates. 8.To make the balloon inflate faster, shake the bottle gently. Remember how we said that air currents make dry ice sublimate more quickly into carbon dioxide? 9.When the balloon is fully inflated, remove it from the bottle and tie it off. 10.Go and get the first balloon that you blew up with your own breath. 11.Toss up both balloons into the air.

Notice how the balloon filled with carbon dioxide gas falls quickly to the ground? Why?

The answer That's because carbon dioxide is heavier than air.

Next Touch the air filled balloon with a piece of dry ice What do you think will happen?

Steps/Precautions Wearing insulated gloves and using tongs, pick up a piece of dry ice and touch it to the balloon that you blew up with air [not the one you filled with carbon dioxide]. What happens to the balloon?

Hero’s engine Using a push pin, or a straight pin held in pliers, poke two holes into opposite sides of a film can, near the bottom. The holes should be off - center, like pinwheel rockets. Tie a loop in a length of thread. The loop should fit loosely over the cap of the film can, so that when you loop it over the cap, and snap the cap onto the can, you can hold the can by the remaining length of thread. Place a small piece of dry ice into the can. Then quickly add some warm water, and close the lid, with the thread attached. Lift the can by the thread, and watch what happens.

Hero’s engine

Singing spoon Hold a warm spoon by its handle, and press it firmly against a chunk of dry ice. The spoon will scream loudly as the heat of the spoon causes the dry ice to instantly turn to gas where the two make contact. The pressure of this gas pushes the spoon away from the dry ice, and without contact, the dry ice stops sublimating. The spoon falls back into contact again, and the cycle repeats. This all happens so quickly that the spoon vibrates, causing the singing sound you hear.