Question

For an ideal binary liquid solution with $P_A^0>P_B^0$ which relation between $X_A$ (mole fraction of A in liquid phase) and $Y_A$ (mole fraction of A in vapour phase) is correct, $X_B$ and $Y_B$ are mole fraction of B in liquid and vapour phase respectively:

• A. $X_A=Y_A$
• B. $X_A>Y_A$
• C. $\frac{X_A}{X_B}<\frac{Y_A}{Y_B}$
• D. $X_A,Y_A,X_B$ and $Y_B$ cannot be correlated

Answer 1

The correct option is C $\frac{X_A}{X_B}<\frac{Y_A}{Y_B}$

$P_A^{\prime }=P_A^0\cdot X_A=P_M\cdot Y_A$

$P_B^{\prime }=P_B^0\cdot X_B=P_M\cdot Y_B$

$\therefore \frac{P_A^0}{P_B^0}\cdot \frac{X_A}{X_B}=\frac{Y_A}{Y_B}$

$\because \frac{P_A^0}{P_B^0}>1\therefore \frac{X_A}{X_B}<\frac{Y_A}{Y_B}$

Hence, the correct option is $C$