Dry ice is the solid form of carbon dioxide (CO2). Dry ice is 'dry' because, under normal atmospheric pressures, carbon dioxide doesn't exist as a liquid. A block of dry ice doesn't melt. It changes directly from a solid to a gas, a process that's known as sublimation.
Dry ice sublimates at −78.5 °C (−109.3 °F) at Earth atmospheric pressures. This extreme cold makes the solid dangerous to handle without protection due to burns caused by freezing (frostbite). While generally not very toxic, the outgassing from it can cause hypercapnia due to buildup in confined locations.
