急...點解固體的二氧化碳叫"乾冰"? 唔該

Dry ice is the genericized trademark[1] for solid carbon dioxide. It is commonly used as a versatile cooling agent.

Unlike water, which passes its solid point and becomes molten, dry ice sublimes, changing directly to a gas at atmospheric pressure. Its sublimation and deposition point is -78.5 °C (-109.3 °F). Its enthalpy of sublimation (ΔHsub) @ -78.5 °C (-109.3 °F) is 199.0 kJ/kg (245.5 BTU/lb). The low temperature and direct sublimation to a gas makes dry ice a very effective coolant, since it is colder than ice and leaves no moisture as it changes state.