The vapour pressure of a pure liquid A is 70 torr at 27 ° C . It forms an ideal solution with another liquid B. The mole fraction of B is 0.2 and total vapour pressure of the solution in 84 torr at 27

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The vapour pressure of a pure liquid A is 70 torr at 27 ° C . It forms an ideal solution with another liquid B. The mole fraction of B is 0.2 and total vapour pressure of the solution in 84 torr at 27 ° C . The vapour pressure of pure liquid B at 27 ° C is

TestHub · Accepted Answer

According to Raoult's law, p = p A o . X A + p B o . X B Here p A o = 70 torr , X A = 1 - X B = 1 - 0.2 = 0.8 , p = 84 torr, X B = 0.2 and p B o = ? So 84 torr = 70 torr × 0.8+ p B o × 0.2 or p B o = 84 torr - 56 torr 0.2 = 140 torr .

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