Dry ice is solid carbon dioxide, which is condensed into colorless liquid under the pressure of 6250.5498 kPa, and then rapidly solidified under low pressure. Once dry ice is placed at normal temperature and pressure, it will quickly absorb heat and sublimate into gas.

Carbon dioxide is invisible. After sublimation, it is not smoke, but fog. When carbon dioxide changes from solid to gas, it absorbs a lot of heat, which makes the temperature of the surrounding air drop rapidly, and the air temperature drops accordingly. Its solubility in water vapor becomes smaller, and the water vapor liquefies and releases heat, turning into small water droplets, which is fog.

This is the same as the "white fog" of popsicles in summer. It's all water droplets, not other gaseous substances. That is, we see white fog instead of white smoke.

The temperature of dry ice is much lower than that of water, so it is equivalent to heating dry ice, which absorbs heat and sublimates, reducing the temperature of water and even freezing it.

Extended data:

Use of dry ice

food service industry

1. Add dry ice to wine, cocktail or drink, it will be cool and delicious when drinking, and the cup will be filled with smoke, which is very pleasant.

2. Add dry ice when making ice cream, and the ice cream will not melt easily. Dry ice is especially suitable for cold storage and transportation of takeaway ice cream.

3. Adding dry ice to seafood dishes in star-rated hotels and restaurants can create a white smoke landscape and improve the level of banquets, such as making lobster sashimi.

4, lobster, crab, shark fin and other seafood frozen and refrigerated. Dry ice will not change water, and it is cleaner than water-cooled storage. Widely used in Europe, America, Japan and other countries.

Refrigerated transportation field

1, cryogenic refrigeration for medical use and cryogenic transportation of special drugs such as plasma and vaccines.

2. Long-distance and short-distance transportation of electronic cryogenic materials and precision components.

3. Fresh-keeping transportation of high-grade foods such as high-grade beef and mutton.

Entertainment field

Widely used in stage, theater, film and television, wedding, celebration, party and so on. There are countless special effects classic plays made of dry ice in China and even in the world.

Fire field

Dry ice is used to put out fires, such as some low-temperature fire extinguishers, but the application of dry ice in this respect is less, that is, the market level is low.

Common sublimation phenomenon:

The process of solid iodine directly changing into iodine vapor by heating is sublimation.

The gradual shrinking of mothballs is sublimation.

When ice is heated, it turns directly into steam, which is sublimation.

The bulb will turn black after a long time because the filament (tungsten) is sublimated by heat and the gas condenses when it touches the glass.

It is sublimation that dry ice becomes gaseous carbon dioxide when heated.

The fog seen on the stage is a small water droplet that absorbs heat by sublimation of dry ice and is liquefied by water vapor in the air when it is cold, which reduces the surrounding temperature.

Baidu encyclopedia-dry ice