Fugacities in an Ideal Binary Mixture

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This Demonstration shows how the fugacities of benzene () and toluene (
) change with temperature and molar composition at constant pressure. The liquid mixture is an ideal solution and the gas phase is ideal, so Raoult's law models vapor-liquid equilibrium. Use sliders to vary the temperature and overall mole fraction of benzene. Use buttons to view the temperature-composition diagram (
-
-
), the fugacity-temperature plot or both plots at once.
Contributed by: Garrison J. Vigil and Rachael L. Baumann (July 2015)
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 saturation pressures were calculated using the Antoine equation:
,
where represents either benzene or toluene (
or
),
is temperature (°C), and
,
and
are Antoine constants.
The fugacity of a component depends on temperature and molar composition.
In the liquid region:
,
where is the liquid mole fraction and both
and
have units of bar.
In the vapor region:
,
where is the vapor molar composition and
is the total pressure (bar).
When vapor and liquid are in equilibrium (VLE):
.
The screencast video at [1] explains how to use this Demonstration.
Reference
[1] Fugacities in an Ideal Binary Mixture [Video]. (Dec 1, 2016) www.colorado.edu/learncheme/thermodynamics/FugacitiesIdealBinaryMixture.xhtml.
Permanent Citation