The term sublimation is used to describe the conversion of a solid directly to a gas, without passing through the liquid state. This process is an endothermic process which means that it needs a supply of energy to happen. It happens at a temperature and pressure that is below the triple point of a substance. There are some substances that prefers sublimation rather than evaporation like arsenic and carbon. This is for the reason that the pressure for the triple point of these substances are very high and it would be difficult for them to be at the liquid state. The energy needed for sublimation to happen is calculated from the sum of enthalpy of vaporization and enthalpy of fusion.
