The following temperature/composition data were obtained for a mixture of octane (O) and methylbenzene (M) at 1.00 atm, where x is the mole fraction in the liquid and y is the mole fraction in the vapor at equilibrium.
Θ/ºC
110.9
112.0
114.0
115.8
117.3
119.0
121.1
123.0
xM
0.908
0.795
0.615
0.527
0.408
0.300
0.203
0.097
yM
0.923
0.836
0.698
0.624
0.527
0.410
0.297
0.164
The boiling points are 110.6 ºC and 125.6 ºC for M and O, respectively. Plot the temperature/composition diagram for the mixture. What is the composition of the vapor in equilibrium with the liquid of composition a) xM = 0.250 and b) xO = 0.250?