T-x-y Diagram of Ideal Solution

Home -> Solved Problems -> Thermodynamics ->


From the following vapor pressure data, construct the temperature - composition diagram at 1 atm, for the system benzene-toluene, assuming ideal solution behavior.

Temperature oC

Vapor pressure, mm Hg

Benzene

Toluene

80

760

300

92

1078

432

100

1344

559

110.4

1748

760

Calculations:

Mole fraction in liquid phase (x) is given by,

x = (pt - pB)/(pA - pB)

The corresponding equilibrium mole fraction in vapor phase (y) is,

y = pAx/pt

Using these equations, for the various temperatures given, the following data for x and y are obtained, for the total pressure of 1 atm

T x y
80 1.000 1.000
92 0.508 0.720
100 0.256 0.453
110.4 0.000 0.000

From the above-calculated data, the following T-x-y diagram is drawn.