Question

The mole fraction of ethanol in water is \(0.08\). Its molality is
(A) \(6.32 \mathrm{~mol} \mathrm{~kg}^{-1}\)
(B) \(4.83 \mathrm{~mol} \mathrm{~kg}^{-1}\)
(C) \(3.82 \mathrm{~mol} \mathrm{~kg}^{-1}\)
(D) \(2.84 \mathrm{~mol} \mathrm{~kg}^{-1}\)

Answer 1

Ans(B)

\begin{aligned}
: \text { Molality } &=\frac{\mathrm{X}_{\mathrm{EtOH}}}{\mathrm{x}_{\mathrm{H}_{2} \mathrm{O}}} \times \frac{1000}{\mathrm{MW}_{\text {solvent }}} \\
&=\frac{0.08}{0.92} \times \frac{1000}{18} \\
&=4.83 \mathrm{~mol} \mathrm{~kg}^{-1}
\end{aligned}