sublimation The transformation of a substance directly from the solid to the vapor state without its becoming liquid. All solids will sublime below their triple point (at which solid, liquid, and vapor are all in equilibrium), but in only a few cases – including dry ice, iodine, naphthalene, and sulfur – is this at a high enough temperature and rate to be useful for purification. Only those molecules with above-average energy are able to overcome the cohesive forces holding the liquid together and escape from the surface. Freeze-drying is by sublimation. Related categories • PHYSICAL CHEMISTRY • HEAT AND THERMODYNAMICS Also on this site: Encyclopedia of Alternative Energy & Sustainable Living Encyclopedia of History Transport Concepts & Designs (partner site) |