2.  Dry ice is frozen Carbon Dioxide, or CO 2, which is a gas under standard temperature and pressure conditions. The atmosphere contains about.035% of this gas. CO 2 is a greenhouse gas, which means it absorbs light at infrared wavelengths.  An increase in the concentration of this gas would, some scientists believe, cause an increase in the atmosphere's average temperature. The high concentration of CO 2 in the atmosphere of the planet Venus is said to contribute to that planet's high average temperature.

3.  At normal atmospheric pressure on this planet, frozen CO 2 doesn't melt into a liquid, but rather evaporates directly into its gaseous form. Hence the name dry ice. This process is called sublimation.  1 pound of dry ice, when it "sublimes" (turns to gas) will produce 250 liters of gas at atmospheric pressure, enough to fill 125 2-liter bottles. That's a lot of gas!

4.  Dry ice is commonly available from ice dealers in two forms: flat square slabs a few inches thick and about eight inches on a side; or cylinders about half an inch in diameter and from a half to 2 ½ inches long. The price for ten pounds is around six dollars. If you buy less than this you will pay about a dollar per pound.

5.  Due to its extremely cold temperature (-78.5 o C, or -109.3 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.

6.  When you place dry ice into some warm or hot water, clouds of white fog are created. This white fog is not the CO 2 gas, but rather it is condensed water vapor, mixed in with the invisible CO 2. The extreme cold causes the water vapor to condense into clouds.  Do not allow anyone to lay down in this fog, or allow babies or pets into it, as CO 2 gas does not support life.

7.  This is the demonstration that we are going to do today in Mrs. Farner’s lab.  Search “Steve Spangler Science” on a search engine to find more dry ice experiments. Remember to heed all previous safety precautions.