How many grams of ethylene glycol (molar mass $62 g mo l^{- 1}$ ) must be dissolved in $1.00 kg$ of water so that the solution freezes at $- 10. 0^{\circ} C$ ? Use $K_{f} = 1.86 K kg mo l^{- 1}$ , and give the answer to the nearest integer.

Numerical answer type, answer in g, tolerance 1.

Answer: 333 g

Δ T_{f} = 10.0 K = K_{f} m

, so

m = 10.0/1.86 = 5.376 mol k g^{- 1}

. For

1.00 kg

of water this is

5.376

mol, i.e.

5.376 \times 62 = 333.3 \approx 333 g