Question

Consider an ideal vapour-liquid binary mixture, find the total pressure if the vapour pressure of A is 260 mmHg and the vapour pressure of B is 520 mmHg and the composition of A in mole fraction is 0.55.

(a) 177 mmHg

(b) 277 mmHg

(c) 377 mmHg

(d) 477 mmHg

The question was posed to me in a national level competition.

This question is from Distillation-Vapour Liquid Equilibria topic in portion Distillation of Mass Transfer

Answer 1

Right choice is (c) 377 mmHg

To explain: Total pressure = (vapour pressure of A * mole fraction) + vapour pressure of B*( 1- mole fraction) = 377 mmHg.