Question

The vapour pressures of A and B at 25°C are 90 mm Hg and 15 mm Hg respectively. If A and B are mixed such that the mole fraction of A in the mixture is 0.6, then the mole fraction of B in the vapour phase is X x 10^–1 . The value of x is ........ (Nearest integer)

Answer 1

Answer is (1)

Given PA° = 90 mm Hg, at 25°C 

PB° = 15 mm Hg

= (0.6 × 90) + (0.4 × 15) 

= 54 + 6 = 60 mm 

Now mol fraction of B in the vapour phase

therefore: x = 1