Q. Vapour pressure of pure A = 100 torr, moles = 2; vapour pressure of pure B=80 torr, moles = 3. Total vapour pressure of the mixture is
A) 440 torr
B) 460 torr
C) 180 torr
D) 88 torr
Explanation
(d)
$P_{total} = P_{A}^{\circ}X_{A} + P_{B}^{\circ}X_{B}$
where , P = vapour pressure
X = mole fraction
Total moles of A and B = 5
Mole fraction of compound A= $\frac{2}{5}$
Mole fraction of compound B= $\frac{3}{5}$
then$,\ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ P_{total}\ = \ 100\ \times \frac{2}{5} + 80 \times \frac{3}{5}\ \$
= 88 torr
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.