Question

For an ideal binary liquid solution with $p_{A}^{\circ} >\,p_{B}^{\circ} \,x_{A}$ and $y_{A}$ represent the mole fraction of A in liquid phase and vapour phase respectively whereas $x_{B}$ and $y_{B}$ represent the mole fraction of B in liquid phase and vapour phase respectively. Therefore which of the following relation is correct?

• A. $x_{A} = y_{A}$
• B. $x_{A} >\, y_{A}$
• C. $\frac{x_{A}}{x_{B}} < \frac{y_{A}}{y_{B}}$
• D. $\frac{x_{A}}{x_{B}} > \frac{y_{A}}{y_{B}}$

Answer 1

Answer: (C)

$P'_{A} =P^{\circ}_{A}\,x_{A}=p_{\text{sol}} \times y_{A}$
$P'_{B}=P^{\circ}\, _{B}x_{B}=p_{\text{sol}} \times y_{B}$
$\therefore \frac{Y_{A}}{Y_{B}}=\frac{P_{A}^{\circ}}{P^{\circ}_{B}}\times\frac{X_{A}}{X_{B}}$
Since $P_{A}^{\circ} >\,P_{B}^{\circ}$
$\therefore \frac{Y_{A}}{Y_{B}}>\,\frac{X_{A}}{X_{B}}$