4:30pm, Hawking Auditorium, Mitchell Physics Building
van der Waals interactions or Force
In physical chemistry, the van der Waals force (or van
der Waals' interaction), named after Dutch scientist
Johannes Diderik van der Waals, is the sum of the
attractive or repulsive forces between molecules (or
between parts of the same molecule) other than those
due to covalent bonds, or the electrostatic interaction
of ions with one another, with neutral molecules, or
with charged molecules. The term includes:
force between two permanent dipoles (Keesom
force)
force between a permanent dipole and a
corresponding induced dipole (Debye force)
 force between two instantaneously induced dipoles
(London dispersion force).
It is also sometimes used loosely as a synonym for the
totality of intermolecular
forces.
Johannes Diderik van der Waals
Leiden, The Netherlands, 1837 -1923
Chemical Forces and Interactions
Ion-Ion
Dipole-Induced Dipole
Ion-Dipole
Instantaneous Dipole-Induced Dipole
(London Dispersion Forces)
Dipole-Dipole
Ion-Induced Dipole
Intermolecular Forces:
An Iconic graphic: Plots
of boiling points of EHx
vs. Molecular weights
Instantaneous dipole/Induced dipole
Vander Waal Forces of London type:
Depend on molecular volume
Hexafluorocyclohexane or 1,2,3,4,5,6 CH6F6.
Van der Waals radius (non-bonding distance)
Oxygen is more soluble in water than nitrogen is. Water in
equilibrium with air contains approximately 1 molecule of dissolved
O2 for every 2 molecules of N2, compared to an atmospheric ratio of
approximately 1:4. The solubility of oxygen in water is temperaturedependent, and about twice as much (14.6 mg·L−1) dissolves at 0
°C than at 20 °C (7.6 mg·L−1). At 25 °C and 1 standard
atmosphere (101.3 kPa) of air, freshwater contains about 6.04
milliliters (mL) of oxygen per liter, whereas seawater contains about
4.95 mL per liter. At 5 °C the solubility increases to 9.0 mL (50%
more than at 25 °C) per liter for water and 7.2 mL (45% more) per
liter for sea water.