Chemistry- Intermolecular Forces

Intermolecular forces - Forces between 2 Different Molecules

3 Main Types of Intermolecular Forces

  • London Dispersion Forces - Only forces acting between non-polar molecules

  • Dipole-Dipole Forces- Attractions between polar molecules

  • Hydrogen Bonding/Bond - Bonded to N, O, F Unshared electron pair on adjacent

Phase Changes

Changing phases involves overcoming intermolecular forces.

Solid —→ Liquid: Melting

Liquid —→ Gas: Vaporization

Solid ——> Gas: Sublimation

Liquid —→ Solid: Freezing

Gas —→ Liquid: Condensation

Gas —→ Solid: Deposition

Phase Diagrams :

K = C + 273.15

Triple Point: All 3 phases co-exist in equilibrium

Above Critical point: Its in the supercritical point

Normal: One atmosphere of pressure

The Phase Diagram for water is different because the solid-liquid equilibrium line has a negative slope

Features of Phase Diagrams (M11Q1) – UW-Madison Chemistry 103/104 ...

Cohesion/Adhesion

  • Cohesion: forces of attraction between like molecules

  • Adhesion: forces of attraction between unlike molecules

Cohesive forces cause Surface Tension

Molar Heat Of Fusion: energy required to melt one mole of a substance

Molar Heat Of Vaporization: the amount of heat needed to vaporize one mole of a substance

Specific Heat Capacity: the amount of energy required to raise the temp. of a substance by 1 (C)