CHEM 123 Chapter Notes - Chapter 3: Triple Point, Supercooling, Phase Diagram

• School: UBC
• Department: Chemistry
• Course: CHEM 123
• Professor: Glenn Sammis

Document Summary

Intermolecular forces and some properties of liquids: surface tension. Surface tension ( ): the energy or work required to extend the surface of a liquid; in units of energy per unit area (j m-2) Surface tension decreases with increased temperature: as temperature/intensity of molecular motion increase, intermolecular forces become less effective = less work is required to extend the surface of a liquid. Liquid wets the surface: when drop of liquid spreads across a surface. Cohesive forces: intermolecular forces between like molecules, such as within a drop of liquid. Adhesive forces: intermolecular forces between unlike molecules, such as molecules of a liquid and of a surface with which it is in contact. When cohesive forces > adhesive, drop maintains shape; adhesive > cohesive, the energy for spreading the drop into a film is met through work done by the collapsing drop.