Search any question & find its solution
Question:
Answered & Verified by Expert
The mole fraction of ethanol in water is $0.08$. Its molality is
Options:
Solution:
1814 Upvotes
Verified Answer
The correct answer is:
$4.83 \mathrm{~mol} \mathrm{~kg}^{-1}$
Hint:
$\begin{aligned} \text { Molality } &=\frac{\mathrm{x}_{\mathrm{EtOH}}}{\mathrm{x}_{\mathrm{H}_{2} \mathrm{O}}} \times \frac{1000}{\mathrm{MW}_{\text {solvent }}} \\ &=\frac{0.08}{0.92} \times \frac{1000}{18} \\ &=4.83 \mathrm{~mol} \mathrm{~kg}^{-1} \end{aligned}$
$\begin{aligned} \text { Molality } &=\frac{\mathrm{x}_{\mathrm{EtOH}}}{\mathrm{x}_{\mathrm{H}_{2} \mathrm{O}}} \times \frac{1000}{\mathrm{MW}_{\text {solvent }}} \\ &=\frac{0.08}{0.92} \times \frac{1000}{18} \\ &=4.83 \mathrm{~mol} \mathrm{~kg}^{-1} \end{aligned}$
Looking for more such questions to practice?
Download the MARKS App - The ultimate prep app for IIT JEE & NEET with chapter-wise PYQs, revision notes, formula sheets, custom tests & much more.