Question

A liquid mixture of benzene ($B$) and toluene ($T$) contains 1 mole each of $B$ and $T$.

$P_T^o=4.274kN{m}^{-2}$ and $P_B^o=13.734kN{m}^{-2}$.

If the pressure is reduced further, pressure (in $kN{m}^{-2}$) (write only integer part) at which the last trace of liquid does disappear is__________.

Answer 1

$\frac{1}{P_{Total}}=\frac{X_B}{P_B^o}+\frac{X_T}{P_T^o}$
$\frac{1}{P_{Total}}=\frac{1}{2\times 13.734kN{m}^{-2}}+\frac{1}{2\times 4.274kN{m}^{-2}}$
$\frac{2}{P_{Total}}=\frac{1}{13.734kN{m}^{-2}}+\frac{1}{4.274kN{m}^{-2}}$
$\frac{2}{P_{Total}}=\frac{13.734kN{m}^{-2}+4.274kN{m}^{-2}}{13.734kN{m}^{-2}\times 4.274kN{m}^{-2}}$
$\frac{2}{P_{Total}}=\frac{0.3068}{kN{m}^{-2}}$
$P_{Total}=6.519kN{m}^{-2}$