what is sublimation in chemistry

Sublimation is a physical change of state in which a substance transitions directly from the solid phase to the gas phase, without passing through an intermediate liquid phase). It is an endothermic process that occurs at temperatures and pressures below the substances triple point). Sublimation is a technique used by chemists to purify compounds. A solid is typically placed in a sublimation apparatus and heated under vacuum. Under this reduced pressure, the solid volatilizes and condenses as a purified compound on a cooled surface, leaving a non-volatile residue of impurities behind. Once heating ceases and the vacuum is removed, the purified compound may be collected from the cooling surface). Some examples of substances that sublime readily include iodine, dry ice, menthol, and camphor.