The mass of ice that will separate out on cooling a solution containing 50 g of ethylene glycol in 3 — Solutions and Colligative Properties Chemistry Question

💡 Solution & Explanation

At $-6.0^\circ\text{C}$, $\Delta T_f = 6.0$. Required molality of the remaining liquid solution is $m = \Delta T_f / K_f = 6.0 / 1.86 \approx 3.2258 \text{ m}$. Moles of ethylene glycol ($M=62$) $= 50 \text{ g} / 62 \text{ g/mol} = 0.80645 \text{ mol}$. Mass of liquid water required to maintain this molality is $W = n / m = 0.80645 / 3.2258 = 0.250 \text{ kg} = 250 \text{ g}$. The initial mass of water was 375 g, so the mass of ice separated out is $375 \text{ g} - 250 \text{ g} = 125 \text{ g}$. Therefore, correct answer is 0125.