Three Intermolecular Potential Models

Requires a Wolfram Notebook System
Interact on desktop, mobile and cloud with the free Wolfram Player or other Wolfram Language products.
This Demonstration considers three models for intermolecular potentials: square-well, Sutherland, and Lennard-Jones. Potentials for molecule (blue), molecule
(green), and an
mixture (orange) are shown. Use a slider to vary the binary interaction parameter
, which represents how non-ideal the mixture is (
for the ideal case). The attractive-strength ratio represents the relative well depths of
to
. The diameter ratio represents the relative sizes of the molecules. The relative width is the ratio of attractive diameter to the repulsive diameter.
Contributed by: Megan E. Maguire and Rachael L. Baumann (December 2013)
Additional contributions by: John L. Falconer and Nick Bongiardina
(University of Colorado Boulder, Department of Chemical and Biological Engineering)
Open content licensed under CC BY-NC-SA
Snapshots
Details
The square-well potential is:
The Sutherland potential is:
The Lennard–Jones potential is:
where is the intermolecular potential,
is the distance between the molecule centers,
is the molecular diameter,
is the depth of the potential well, and
is the well width for square-well potential.
The attractive strength parameter of the mixture is given by:
,
where is the binary interaction parameter, and
and
are the attractive strength parameters for molecules
and
.
A larger negative number for the binary interaction parameter represents stronger interactions between and
relative to those between
and
or
and
. Analogously, a smaller positive number represents weaker interactions.
The molecular diameter parameter for the mixture is:
,
where and
are the diameter parameters for molecules
and
.
A screencast video at [1] shows how to use this Demonstration.
Reference
[1] Three Intermolecular Potential Models. www.colorado.edu/learncheme/thermodynamics/ThreeIntermolecularPotentialModels.html.
Permanent Citation