Q.

The total pressure observed by mixing two liquids A and B is 350 mm Hg when their mole fractions are 0.7 and 0.3 respectively. The total pressure becomes 410 mm Hg if the mole fraction are changed to 0.2 and 0.8 respectively for A and B. The vapour pressure of pure A is ______ mm Hg. (Nearest integer) Consider the liquids and solutions behave ideally.                     [2023]


Ans.

(314)

XAPA0+XBPB0=Ps

0.7PA0+0.3PB0=350

and 0.2PA0+0.8PB0=410

 PA0=314 torr.