Question

The mole fraction of ethanol in water is 0.08. Its molality is:

• A. $6.32molk{g}^{-1}$
• B. $4.83molk{g}^{-1}$
• C. $3.82molk{g}^{-1}$
• D. $2.84molk{g}^{-1}$

Answer 1

The correct option is B $4.83molk{g}^{-1}$

Given, mole fraction of ethanol is 0.08
$\therefore$ mole fraction of water $=1-0.08=0.92$
Again, 0.92 mol of water $=\frac{0.92\times 18}{1000}=0.0165Kg$

So, the molality of the solution is $\frac{0.08}{0.0165}=4.848mol/kg$