What is dry ice? How is it prepared?

Dry ice is the solid form of carbon dioxide (CO2). It is called "dry ice" because it doesn't melt into a liquid form like regular ice; instead, it sublimates directly from a solid to a gas at temperatures above -78.5°C (-109.3°F) at standard atmospheric pressure. This sublimation process makes dry ice ideal for various applications, including cooling and freezing.

Dry ice is typically prepared by compressing and cooling gaseous carbon dioxide until it liquefies. Then, the pressure is released, causing the liquid carbon dioxide to rapidly expand and evaporate, leaving behind solid dry ice. This process is similar to how regular ice is formed, but instead of water vapor, carbon dioxide is used. The solid carbon dioxide is then formed into blocks, pellets, or other shapes for commercial use.