Question

An ideal solution was obtained by mixing methanol and ethanol. If the partial vapour pressure of methanol and ethanol are $2.619K{P}_a$ and $4.556K{P}_a$ respectively, then the composition of vapour (in terms of mole fraction) will be:

• A. 0.635 MeOH, 0.365 EtOH
• B. 0.365 MeOH, 0.635 EtOH
• C. 0.574 MeOH, 0.326 EtOH
• D. 0.173 MeOH, 0.827 EtOH

Answer 1

Answer: (B)

0.365 MeOH, 0.635 EtOH

for ideal
$\frac{P_A}{X_A}=\frac{P_B}{x_B}$

$\frac{P_A}{P_B}=\frac{2\cdot 619}{4\cdot 556}=0\cdot 5746$
So option check

[A] $\frac{X_A}{X_B}=\frac{0\cdot 635}{0\cdot 365}=1\cdot 73$

[B] $\frac{X_A}{X_B}=\frac{0\cdot 365}{0\cdot 635}=0\cdot 5748$

[C] $\frac{X_A}{X_B}=\frac{0\cdot 574}{0\cdot 326}=1\cdot 76$

[D] $\frac{X_A}{X_B}=\frac{0\cdot 173}{0\cdot 827}=0\cdot 209$

Hence, the correct option is $B$