A $0.050 mol k g^{- 1}$ aqueous solution of $K X_{2} SO X_{4}$ freezes at $- 0.25 5^{\circ} C$ . Using $K_{f} = 1.86 K kg mo l^{- 1}$ , determine the experimental van't Hoff factor $i$ (defined by $Δ T_{f} = i K_{f} m$ ) to two decimal places.

Numerical answer type, tolerance 0.01.

Answer: 2.74

Δ T_{f} = 0.255 K

and

K_{f} m = 1.86 \times 0.050 = 0.0930 K

. Hence

i = 0.255/0.0930 = 2.7419 \approx 2.74