WOLFRAM|DEMONSTRATIONS PROJECT

Peng-Robinson Equation of State for Mixtures

​
temperature (K)
391
n-butane liquid mole fraction
x
1
0.97
This Demonstration studies the vapor-liquid equilibrium for a binary mixture of
n
-butane(1) and
n
-octane(2) by plotting isotherms on a log pressure versus log volume graph. The isotherms are calculated using the Peng–Robinson equation of state for mixtures. Use the sliders to select the temperature and the mole fraction
x
1
of the liquid. The mole fraction of the vapor
y
1
and the equilibrium pressure are calculated from Raoult's law and are displayed in the upper-right corner along with
x
1
. The dashed black line connects the liquid mole fraction on the blue isotherm to the vapor mole fraction on the green isotherm.