A 0.50 m aqueous solution of a salt AB2 (giving three ions per formula unit, i = 1 + 2alpha) freezes at -1.395 degC. Take K_f = 1.86 K kg mol^-1. Find the degree of dissociation alpha (two decimal places).

JEE Main levelNumerical answerDifficulty 2 of 3so100

A $0.50 m$ aqueous solution of a salt $AB X_{2}$ (giving three ions per formula unit, $i = 1 + 2 α$ ) freezes at $- 1.395^{\circ} C$ . Take $K_{f} = 1.86 K kg mo l^{- 1}$ . Find the degree of dissociation $α$ (two decimal places).

Numerical answer type, tolerance 0.01.

i = Δ T_{f} / (K_{f} m) = 1.395/ (1.86 \times 0.50) = 1.50

. From

i = 1 + 2 α

α = (1.50 - 1) /2 = 0.25