Question

The mass of ice separated out on cooling a solution containing 50 g ethylene glycol in 200g water to $-{9.3}^{o}C$ is:

$[K_f$ for $H_{2}O=1.86$ K molality${}^{-1}]$

• A. $38.71$ g
• B. $61.29$ g
• C. $138.71$ g
• D. $161.29$ g

Answer 1

The correct option is A $38.71$ g

The mass of ice is $38.71g$

$\Delta T=\frac{1000\times K_f\times w}{m\times W}$

$9.3=\frac{1000\times 1.86\times 50}{62\times W}$

$\therefore W_{water}=161.29g$

The total mass of the solution is $200g$

$\therefore$ Ice separated $=200-161.29=38.71g$

Hence, the correct option is $\text{A}$