The vapor liquid equilibrium relation for an ideal binary system is given by

y*${_A}$ = $\frac{\alpha{_A}{_B}x{_A}}{1 + ({\alpha}{_A}{_B} – 1)x{_A}}$

Here x${_A}$ and y*${_A}$ are the mole fractions of species A in the liquid and vapor, respectively. The relative volatility (${\alpha}{_A}{_B}$) is greater than unity.

The liquid mole fraction x${_A}$ at which the maximum difference between the equilibrium vapor mole fraction and liquid mole fraction occurs is

1. $\frac{1}{(1+\sqrt{{\alpha}_{AB}})}$
2. $\frac{0.75}{(1+\sqrt{{\alpha}_{AB}})}$
3. $\frac{0.5}{(\sqrt{{\alpha}_{AB}+1)}}$
4. $\frac{0.75}{(\sqrt{{\alpha}_{AB}+1})}$