$62 g$ of ethylene glycol (molar mass $62 g mo l^{- 1}$ ) is dissolved in $500 g$ of water ( $K_{f} = 1.86 K kg mo l^{- 1}$ ). The solution is cooled slowly to $- 7.44^{\circ} C$ and equilibrium is reached with pure ice separating (assume the freezing point law holds at all concentrations). Find the mass of ice that has separated, in grams (nearest integer).

Numerical answer type, answer in g, tolerance 1.

Answer: 250 g

- 7.44^{\circ} C

the liquid must have

Δ T_{f} = 7.44 K

, so

m = 7.44/1.86 = 4.0 mol k g^{- 1}

. All

1.0 mol

of glycol stays in solution, so water remaining

= 1.0/4.0 = 0.250 kg

(250 g). Ice formed

= 500 - 250 = 250 g