This easy demonstration shows students the approximate size of one mole of carbon dioxide gas and gives the opportunity for an irresistible pun.

Approximately 1/4 lb of dry ice
Triple beam balance (0.1 g accuracy)
Hammer to crush dry ice
Latex surgical glove
Towel to contain dry ice while crushing

This demonstration should follow a discussion of elementary gas laws in which the volume of one mole of gas has been introduced. It also serves to illustrate the idea of the mole as a measure of amount of substance.

Explain to your class that dry ice is frozen carbon dioxide gas and that when it "disappears" the solid is really turning to gas (subliming). Explain that the purpose of the demonstration is to show how much volume one mole of gas occupies.

Crush some dry ice by wrapping a piece in a towel and pounding it with a hammer. Weigh out one mole of the crushed dry ice (44 g) on the balance and carefully pour the coarse powder into the latex glove. Explain that the glove now contains one mole of carbon dioxide. Seal the open end of the glove by tying it in a knot or by twisting and tying with a wire. Set the glove containing the dry ice aside and allow the frozen gas to sublime while you discuss other topics. It will take 20-30 minutes before all the solid sublimes.

When all the solid has turned to gas, the glove should have inflated to roughly the size of a basketball. At this point you might calculate the expected volume of the gas by using the ideal gas law. Here is an excellent opportunity to ask the rhetorical question, "To what level of accuracy to we know the volume of the inflated glove?" The answer, of course, is to five digits.

The use of STP conditions in gas law calculations is becoming less common. The original purpose was quite practical, because gas volumes were often measured under these conditions in some types of work and it gave an intuitive feeling for the amount of gas with which one was working. It is the opinion of this author that STP conditions should be laid to rest in introductory courses; students confuse them with thermodynamic standard conditions (1 atm and 298 K) which have a much broader range of application.

The only imaginable hazards in this demonstration are the danger of frost bite from improper handling of dry ice or the possibility that you will do something stupid like hitting your thumb with the hammer while crushing the dry ice. Watch what you are doing! Use insulated gloves if you feel the need to hold the dry ice in your hands for extended periods of time. Extra dry ice can be allowed to evaporate in a well ventilated area. (The carbon dioxide inflated glove could be used for gas a density demonstration by comparison with a glove similarly inflated with air. The air filled glove will fall at a slower speed.)

None known. I once saw George Gilbert do this.

This demonstration can, of course, be carried out with a good sized balloon of the color of your choice.