At 300 K , the vapour pressure of a solution containing 1 mole of n -hexane and 3 moles of n -heptane is 550 mm of Hg . At the same temperature, if one more mole of n -heptane is added to this solution, the vapour pressure of the solution increases by 10 mm of Hg . What is the vapour pressure in mmHg of n - heptane in its pure state______?

Step-by-step solution

P total = P ∘ hexane .   X hexane + P ∘ heptane . X heptane 550 = P ∘ hexane × 1 4 + P ∘ heptane × 3 4 .. ( i ) After mixing 1 mole n-heptane 560 = P ∘ hexane × 1 5 + P ∘ heptane × 4 5 ..... ( ii ) On solving eq. (i) and (ii) P ∘ heptane = 600   mm of Hg