SUBLIMATION

Some solids can change to vapor state without melting when heated. We called it SUBLIMATION. When the vapor is cooled, the solid forms again. We often use sublimation to separate a mixture of two solids in which one sublimes, but the other does not. For example, iodine from a mixture of sand and iodine by sublimation. When heated, only iodine changes to vapor. The vapor changes back to solid on the side of the funnel.

An inverted test tube is placed over if too much vapor is escaping from funnel.

Substances which sublime include anhydrous aluminum chloride, iodine and benzoic acid, anhydrous iron (III) chloride and anhydrous aluminum chloride.