PHC320H1 Lecture Notes - Lecture 9: Contact Angle, Surface Tension, Monolayer

• School: UTSG
• Department: Pharmaceutical Chemical Engineering and Applied Chemistry
• Course: PHC320H1
• Professor: Shirley Wu

Document Summary

Ym- mass of gas absorbed when the gas molecule is complete single layer. Assumptions made by languir: solid has a uniform surface, absorbed molecules do not interact, adsorbed molecules are localized at spefic active site, only a monolayer can be absorbed. Conttact angle: wettting is a phenomenon of the solid-liquid interface, if you add a drop of liquid to a solid, when it is spontaneously spread, it can be described as complete wetting. If you add a liquid to solid surface, and liquid forms globules, it can be described as incomplete wetting or no wetting. You define the spreading coefficient as the surface tension of old system and new system. When the surface tension of the old system is less than the new system, that means that the interfacial of the old system more stable. The liquid will form globule to mimimize surface area will old system. The critical surface tension depends on the type of solid.