CHEM 120 Study Guide - Midterm Guide: Vaporization, Dynamic Equilibrium, Vapor Pressure

• School: McGill University
• Department: Chemistry
• Course: CHEM 120
• Professor: Ariel Fenster

Document Summary

Interior molecules have more neighbours to be attracted to with intermolecular forces than surface molecules. Increased attraction means a lower state of energy than the surface molecules. Therefore, there is a tendency for liquids to maintain the lowest surface area compared to volume. (spherical drops of rain) Spheres have the smallest surface area to volume ratio than any other geometric shape. To increase surface area means that interior molecules have to be moved to make surface molecules which means work is done. Steel needles remain suspended on the water because energy is required to spread the surface of the water overtop of the needle. The gain in potential energy is greater than can be offset by the loss of the potential energy by the needle falling under the force of gravity. Definition: energy or work required to increase the surface area of a liquid (represented by gamma) units: j/m^2.