The Carbon dioxide Leaky Faucet demonstration, developed by Robert Becker, illustrates the properties of dry ice and carbon dioxide gas. The apparatus is easy to construct. The directions below are for a short version designed to sit on the edge of a lecture bench. You may prefer to make yours a few feet taller and place it on the floor. You can read more about the demonstration in Becker's Twenty Demonstrations Guaranteed to Knock Your Socks Off!, published by Flinn Scientific Inc.
Materials
Three lengths of 3/4 inch PVC pipe (24", 12", and 4")
Two 3/4 inch PVC elbow connectors
One 2 inch length of plastic tubing (1" O.D.)
One 2-L plastic bottle
One ring stand and two clamps
One paper towel
One rubber band
Assemble the PVC pipes and elbows into a faucet shape. You may want to glue them together, but I've found they hold well enough without glue. The 1" O.D. plastic tubing will be used to connect the faucet to the plastic bottle.
Fold the paper towel into a band about two inches wide. Wrap the band around the mouth (short end) of the faucet and hold it in place with the rubber band. The paper towel should extend about 1/4 inch below the PVC pipe.
Using a knife or scissors, make a curved cut near the top of the bottle about three inches wide. This will create a flap for adding dry ice.
Assemble the faucet on the ring stand. It is easier to attach the plastic tube connector to the PVC pipe first, attach the plastic bottle next, and then clamp the faucet to the ring stand.
©2006 W.C. Deese. All Rights Reserved.