Chemistry - Concentration Terms Question with Solution | TestHub

100 g ethanol solution contains 95 g of ethanol$\left({\mathrm{C}}_2{\mathrm{H}}_5\mathrm{O}\mathrm{H}\right)$. Therefore, the mass of water is (100 – 5) g = 5 g.
So mole fraction of ethanol
${\mathrm{X}}_{{\mathrm{C}}_2{\mathrm{H}}_5\mathrm{O}\mathrm{H}}=\frac{\mathrm{n}{\mathrm{C}}_2{\mathrm{H}}_5\mathrm{O}\mathrm{H}}{{\mathrm{n}}_{{\mathrm{C}}_2{\mathrm{H}}_5\mathrm{O}\mathrm{H}}+\mathrm{n}{\mathrm{H}}_2\mathrm{O}}$
$=\frac{95/46}{(95/46)+(5/18)}$
$=\frac{2.065}{2.065+0.2778}=0.881$