The vapour pressure of two pure liquids A and B that form an ideal solution, are 400 and 800 ~mm of Hg respectivelyat a temperature t^ C . The mole fraction of A in a solution of A and B whose boiling point is t^ C will be

Step-by-step solution

V.P. of solution at t^ C =760 ~mm [at b.p., V.P. of solution =atompheric pressure] Thus = P _ A ^ x _ A + P _ B ^ x _ B or P = P _ A ⁰ x _ A + P _ B ⁰ (1- x _ A ) [ x _ A + x _ B =1 ] or 760=400 X _ A +800 (1- X _ A )[ P =760 mmofHg ] or -800+760=-400 x_ A or -40=-400 x _ A or x_ A = 40 400 =0.1 Thus mole fraction in solution is 0.1