At room temperature, carbon dioxide gas is pressurized to about 60? At 10 1325Pa, a part of the steam will be cooled to about -56℃, which will freeze into snowflake-volt solid carbon dioxide. The gasification heat of solid carbon dioxide is very high, which is 364.5 J/g at -60℃. During atmospheric gasification, the ambient temperature can be reduced to about -78℃ and no liquid will be produced, so it is called "dry ice". Ordinary dry ice is lumpy or granular.
Dry ice is mainly used as refrigerant. Dry ice is used as refrigerant in low temperature experiment, artificial rainfall, deburring of molded rubber parts and high-speed grinding. Dry ice can also be used as a quick-frozen preservative for food. In the laboratory, the mixture of dry ice and a volatile liquid (such as ether, acetone or chloroform) can form a low temperature bath of about -77℃.
Function of dry ice
Dry ice that can "call the wind and rain"
1958 it didn't rain for the governor of Liaoning province. The military aircraft of the People's Air Force sprinkled "dry ice" in the sky, and it rained in less than 20 minutes for four consecutive days.
What is dry ice? It is solid carbon dioxide. Under the conditions of pressure and cooling, carbon dioxide gas will become a colorless liquid, and then it will become a snowflake-like solid when the temperature drops. After compression, it will become dry ice, and it can be directly turned into gas at -78℃ under a standard atmospheric pressure.
Why does dry ice have the ability to "call the wind and call the rain"
As we all know, it doesn't rain, either the water vapor doesn't meet the condensation nucleus and can't form small water droplets, or the small water droplets have already condensed because the temperature is too high and have evaporated before falling to the ground. When the plane scatters dry ice in the air, the dry ice immediately evaporates and takes away a lot of heat from the clouds, cooling the clouds to -40℃. Each gram of dry ice can cause 654.38+000 billion small ice crystals, and the surrounding clouds meet small ice crystals.
Dry ice can do great things and small things.
When the train transports fresh fish, it guards beside the fresh fish and plays the role of refrigeration and antisepsis. Dry ice looks like ice and can be used as a preservative, which is much better than ice. When it melts, it won't turn into liquid like ice, but it will all vaporize, and Qian Zhou will be clean. The cooling temperature of dry ice is much lower than that of ice, and the carbon dioxide gas produced by gasification of dry ice can inhibit the reproduction and growth of bacteria.
Dry ice sometimes crouches in the greenhouse of crops, gradually releasing carbon dioxide gas, providing crops with raw materials for photosynthesis, promoting crops to blossom and bear fruit, and improving crop yield.
The work of dry ice is quiet, but sometimes it is vigorous and thrilling. In the coal mining industry, when explosives explode, dry ice immediately vaporizes, producing a large amount of carbon dioxide gas, which not only contributes to the explosion of explosives, but also prevents fire accidents. There are often some combustible gases in the coal seam, but because carbon dioxide, a gas that does not support combustion, isolates the air, it cannot burn.
What lovely dry ice, but don't touch it with your hands like ice. Because the temperature of dry ice is too low, hands will be frostbitten. Frostbite is as hot as burn, and the skin will fester in the future, so don't touch dry ice directly with your hands.