10.1 Intermolecular Forces
| INTERMOLECULAR FORCES | |
|---|---|
| Hydrogen Bonding | -a super strong dipole-dipole force -must have an F-H, O-H, or N-H bond as a pure liquid -must only have F, O, N to hydrogen bond with water (or other H-bond donor) |
| Dipole-Dipole Forces | -interaction between molecules having permanent dipole moments -the larger the dipole moment, the larger the force |
| London Dispersion Forces(van der Waals Forces) | -weak interactions due to a transient (temporary) dipole -all molecules have these but it is the only force present for nonpolar molecules -higher molecular weight, larger surface area, and greater polarizability result in higher London forces |
| Ion-Dipole Forces | -interaction between ions and polar molecules -present when ions are dissolved in polar liquids (such as NaCl in H2O) |
Higher Intermolecular Forces Result in:
↑ Higher Boiling Pts
↑ Higher Enthalpy of Vaporization
↑ Greater Viscosity
↑ Greater Surface Tension
↓ Lower Vapor Pressure
Indicate which has the greatest IMFs in each set.
CH3OH CH3OH
CH3F CH3F
CH4 CH3CH2CH2CH3
Adhesion – The attraction of a substance to other substances.
Cohesion – The attraction of a substance with itself.
Capillary Action – The movement of a fluid through a small diameter tube due to adhesion.