A liquid mixture of A and B is placed in a cylinder-and-piston arrangement. Thepiston is slowly pulled out isothermally so that the volume of the liquid decreases and that of the vapour increases. At the instant when the quantity of the liquid still remaining is negligibly small, the mole fraction of A in the vapour is 0.4. P_A^@=0.4 atm, P_B^@=1.2 atm at the temperature in question. Calculate the total pressure at which the liquid has almost evaporated. Assume ideal behaviour.

A liquid mixture of A and B is placed in a cylinder-and-piston arrange

1.	A liquid mixture of A and B is placed in a cylinder-and-piston arrangement. Thepiston is slowly pulled out isothermally so that the volume of the liquid decreases and that of the vapour increases. At the instant when the quantity of the liquid still remaining is negligibly small, the mole fraction of A in the vapour is 0.4. P_A^@=0.4 atm, P_B^@=1.2 atm at the temperature in question. Calculate the total pressure at which the liquid has almost evaporated. Assume ideal behaviour.
Answer» SOLUTION :0.667 ATM