‹ Back to the paper
Answer the following.
What mass of ethylene glycol must be added to of water to lower the freezing point of water from to…
What mass of ethylene glycol must be added to $5\cdot50\text{ kg}$ of water to lower the freezing point of water from $0^\circ\text{C}$ to $-10\cdot0^\circ\text{C}$?
($K_f$ for water $= 1\cdot86^\circ\text{C kg mol}^{-1}$, molecular weight of ethylene glycol $= 62\cdot0\text{ g mol}^{-1}$)
Answer
Answer
Official answer keyFormula used: Depression of freezing point: dTf = i*Kf*m with Kf = 1.86 K kg mol^-1, M2 = 62 g mol^-1, w1 = 5500 g, dTf = 10 K, so w2 = 1833 g
$w = \dfrac{M_2\,\Delta T_f\,W}{1000\,K_f} = \dfrac{62\times10\times5500}{1000\times1.86} = 1833\ \mathrm{g}$
Final answer: 1833 g
From ISC 2026 Specimen Chemistry Paper 1, question 20(ii).