what is called dry carbon di oxide?

Answer 1

Dry ice.

Answer 2

Dry Ice of course

Dry ice

Dry ice is a genericized trademark for solid ("frozen") carbon dioxide. The term was coined in 1925 by Prest Air Devices, founded in Long Island City, New York in 1923.[1] The name refers to the fact that under normal atmospheric pressure, solid CO2 sublimates, or changes directly into a gas without passing through a "wet" liquid phase. As a general rule, dry ice will sublimate at a rate of five to ten pounds every 24 hours in a typical ice chest.

Dry ice is produced by compressing carbon dioxide gas to a liquid form, removing the heat produced by the compression (see Charles's law), and then letting the liquid carbon dioxide expand quickly. This expansion causes a drop in temperature so that some of the CO2 freezes into "snow", which is then compressed into pellets or blocks. The freezing point of CO2 is -109.3°F or -78.5°C.

Dry ice has many industrial uses, including


Dry ice used to cool drinks in Central Park.
(New York City, New York, U.S.)Cooling foodstuffs, biological samples, and other perishable items, particularly for shipment.
Producing "dry ice fog" for special effects. When dry ice is put into contact with water, the frozen carbon dioxide sublimates into a mixture of cold carbon dioxide gas and cold humid air. This causes condensation and the formation of fog; see fog machine. The use of warm water speeds up sublimation and leads to more vigorous production of fog.
Tiny pellets of dry ice (instead of sand) are shot at a surface to be cleaned. Dry ice is not as hard as sand, but it speeds processing by sublimating to a gas and does not produce nearly as much lung-damaging dust.
Increasing precipitation from existing clouds or decreasing cloud thickness by cloud seeding.[4]
Producing carbon dioxide gas as needed in such systems as the fuel tank inerting system in the B-47 aircraft.
Brass or other metallic bushings are buried in dry ice to shrink them so they will fit inside a machined hole. When the bushing warms back up, it expands and makes an extremely tight fit.
As a cooling supplement for overclocking a central processing unit, a graphics processing unit, or other types of hardware.
A rudimentary cloud chamber can be built using dry ice to supercool alcohol vapor.
Dry ice requires special precautions when handling. It is extremely cold, requiring proper insulating gloves to handle. It constantly produces carbon dioxide gas, so it cannot be stored in a sealed container as the pressure buildup will quickly cause the container to explode. The sublimated gas must be ventilated; otherwise, it may fill the enclosed space and create a suffocation hazard. Special care for ventilating vehicles is needed as well because of the small space. People who handle dry ice should also be aware that carbon dioxide is heavier than air and will sink to the floor. Some markets require those purchasing dry ice to be of 18 years of age or older.