Investigation of the Phase Transition Kinetics Liquid ⇌ Vapour by a Pressure‐jump Relaxation Technique

The construction and performance of an apparatus for the kinetic study of mass transfer processes between gaseous and condensed phases is described. In this method, phase equilibrium is suddenly disturbed by the generation of a pressure jump in the gaseous phase after which the establishment of the new equilibrium state is followed by a sensitive pressure gauge. The application of the method to the kinetics of evaporation and condensation of liquids is described. For water at 20.0°C the evaporation coefficient is found to be α = 1.00 ± 0.03 7 and the condensation coefficient α c = 0.98 ± 0.06 7 . This is the first unambiguous proof that for resting water α = α c = 1.