Evaporation
The escape of molecules from the surface of a liquid into the vapour phase below the boiling point.
Unit
kJ/mol
In depth
Only the fastest molecules at the surface have enough energy to escape, so evaporation removes the highest-energy molecules and cools the remaining liquid. Rate increases with temperature, surface area, air movement and low humidity, and decreases with stronger intermolecular forces.
Examples in the real world
Sweat cooling the skin; a puddle drying on a warm day; volatile solvents evaporating rapidly in a fume hood.