Chemistry - Liquid Solution Question with Solution | TestHub

Given: $n_A=1$, $n_B=3$

Mole fractions:

$X_A=\frac{1}{4}=0.25$, $X_B=\frac{3}{4}=0.75$

According to Raoult's Law:

$$P_{total}=X_A{P}_A^0+X_B{P}_B^0$$

$$P_{total}=0.25(100)+0.75(80)$$

$$P_{total}=25+60=85mmHg$$

For distillate vapor composition, use vapor phase mole fraction:

$$y_A=\frac{25}{85},y_B=\frac{60}{85}$$

$$P_{distillate}=100(0.294)+80(0.706)=85.88mmHg$$

Therefore, the total vapor pressure of the distillate is $85.88mmHg$.