Entropy of evaporation

The entropy of evaporation describes the change in the entropy of a liquid during transition into the gas phase . ${\displaystyle \Delta S_{V}}$

Pictet-Trouton's rule

The standard entropy of evaporation of liquids follows the Pictet-Trouton rule (after Raoul Pictet and Frederick Thomas Trouton ). Accordingly, the value of the standard entropy of evaporation for many non-polar liquids is in the vicinity of ≈ 88–90 J K ⁻¹ mol ⁻¹ . The reason here is the comparably large increase in “disorder” in the transition from liquid to gas. Strong deviations are mostly due to anomalously strongly interconnected molecules , so liquid water is stabilized by hydrogen bonds and structured more strongly (higher short-range order ), which results in a high standard entropy of evaporation . ${\displaystyle \Delta S_{V}=\Delta H_{V}/T_{S}}$

See also

• Enthalpy of fusion
• Entropy of fusion
• Entropy of condensation
• Phase change entropy

credentials

1. ↑ Compare Erich Meister: Basic Practical Course in Physical Chemistry: Theory and Experiments , 2nd Edition. Edition 2012, p. 35.