What is dry ice and what are its uses?
Dry ice is the common name for the solidified (frozen) form of Carbon dioxide. It is so called because it does not melt into a liquid, but changes directly from solid to gaseous form when heated, in a process known as sublimation.
Because of its extremely cold temperature -780C, dry ice is very useful for refrigeration. Its main use is as a cooling agent. Being simple to use and easy to handle using insulated gloves, as well as non-toxic and completely dry, it is widely used as a refrigerant to ship frozen or medical products or to cool materials during production. Food-grade dry ice can also be put into beverages to cool them (but must not be eaten or swallowed).
Another important use of dry ice is for blast cleaning, an effective and environment-friendly way to clean industrial equipment. This method involves shooting pellets of dry ice from a jet nozzle on to the equipment or machinery to be cleaned. This effectively removes residues of materials such as ink, glue, oil, paint etc.
An interesting use of dry ice is in fog machines. When it is kept in water, sublimation ensues, creating dense clouds of smoke-like fog. This is very useful for dramatic effects in stage plays, dances etc. Hence fog machines containing dry ice are used in night clubs, theatres, film shooting sets and amusement parks.
Dry ice is also an excellent material to enliven science lessons and is commonly used in school projects to make a volcano, a cloud chamber etc.
