When you buy dry ice, it will eventually evaporate. Dry ice is actually carbon dioxide that is frozen to below -110 degrees Fahrenheit. As the frozen carbon dioxide absorbs heat, it "sublimates" directly into carbon dioxide gas without ever becoming a liquid. This is what gives it the name "dry ice." Dry ice can last up to 36 hours if you keep it well insulated.
Purchase the dry ice as close as possible to the time you will need it.
Wrap the dry ice in newspapers, paper bags or towels if it does not already come in an insulated bag. Make sure you are wearing insulated gloves any time you touch dry ice. If you touch it with you bare hands, you will suffer frostbite and tissue damage.
Put the wrapped dry ice into an insulated container. The thicker the insulation, the longer the dry ice will last. A styrofoam container works best because it will not become brittle. If you use a plastic container, do not let the dry ice touch the plastic or the extreme cold can cause the plastic to break. Make sure the container has a loose seal, or the build-up of pressure from evaporation will burst the container.
Store the dry ice in a stand-alone freezer if available until you have to move it. Avoid storing dry ice in the freezer department of a refrigerator. The extreme cold will cause the thermostat to turn off the freezer, causing the refrigerator compartment to get warm.
Dispose of dry ice by setting it in a ventilated area and allowing it to evaporate. Do not put it in the sink or toilet - the extreme cold can crack your fixtures.
Do not store dry ice in an unventilated room. The carbon dioxide gas will replace the oxygen, and can cause asphyxiation. Also make sure your car is ventilated with fresh air when you are transporting dry ice inside the car.