Dry ice is solid carbon dioxide. At normal temperature and pressure of 6079.8 kPa, carbon dioxide condenses into colorless liquid, and then rapidly evaporates at low pressure, and then condenses into dense ice-like solid matter. Its temperature is MINUS 78.5℃, which is dry ice. The cold storage capacity of dry ice is more than 1.5 times that of water ice. After absorbing heat, it sublimates into carbon dioxide gas, which has no residue, toxicity and odor, and has sterilization effect. Direct gasification without liquefaction after heating. Dry ice is the solid state of carbon dioxide. Because the temperature of dry ice is very low, the temperature is MINUS 78.5 degrees Celsius, so it is often used to keep objects in a frozen or low temperature state.

At room temperature, when the carbon dioxide gas is pressurized to about 10 1325Pa, a part of the steam will freeze into snowflake volt solid carbon dioxide when it is cooled to about -56℃. 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".