Chem 1320 1st Edition Lecture 40Outline of Last Lecture I. Non- Bonding Outline of Current LectureI. Relationships between intermolecular forces and physical propertiesCurrent Lecture I. Relationships between intermolecular forces and physical properties: Melting point- strength of the intermolecular interaction- Increases so does the melting point- More kinetic energy is needed to overcome these forces **Boiling point- as the strength of the intermolecular interactions increases so does the boiling pointViscosity- how “syrupy” a liquid is and is a form of intermolecular friction. It is the resistance of a liquid to flow.- As the strength of intermolecular interactions increases so the viscositySurface tension- Water droplet in zero gravity forms a sphere shape that minimizes the flow of energy in the system- Changing the surface area has an associated energy - Changing the shape will damage the surface area and the energy of the systemCohesive forces > adhesive - The binding force between the molecules in the droplet are cohesive forces - The binding forces between the liquid molecules and the surface are adhesive forces Vapor Pressure:These notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.- Molecules at the surface are less bound and can obtain enough KE to escape escaped molecules can return to the liquid and be recaptured. The rate of escape is the rate of recapture. This is an equilibrium and there is a vapor pressure that is influenced by the intermolecular forces. - Connection with boiling points: as temperature increases particles will have more KE andmore molecules will escape. At the right temperature the particles in the solution will have enough KE to enter gas phase at any point in the solution. As the boiling point the vapor pressure equals the pressure of the surrounding
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