Question

What is the vapour pressure of pure liquid a at 27 degree celsius is it forms an ideal solution with another liquid be the vapour pressure and mole fraction of fluid liquid be at 27 degree celsius is 142 and 0.2 respectively the total vapour pressure of the solution is 84 at 27° Celsius

Answer 1

Let P1 be vapour pressure liquid.=?
P2 be vapour pressure 2nd liquid=142
P_sol be vapour pressure of solution.=84
X_1,X₂ are mole fractions of liquid 1 and 2 respectively.
Given X2=0.2
∴ X₁=1-0.2=0.8
we have, P_solution = Σ(P_componentX_component) (for solution with more than 1 volatile components.Total vapour pressure is the sum of individual components.)

∴ =P1X₁+P2X2
P1=(P_sol-P2X2)/X_{1
=(84-142*0.2)/0.8
=69.5}