A 0.050 M solution of the chloride BCl of a weak base BOH has pH 5.45 at 298 K. Using K_h = [H+]^2/c (valid for small hydrolysis), find K_b of BOH and report it in units of 10^-5, to two decimal places. Take K_w = 1.0x10^-14.

JEE Advanced levelNumerical answerDifficulty 3 of 3ia016

A 0.050 M solution of the chloride $BCl$ of a weak base $BOH$ has pH 5.45 at 298 K. Using $K_{h} = [H X^{+}]^{2} / c$ (valid for small hydrolysis), find $K_{b}$ of $BOH$ and report it in units of $1 0^{- 5}$ , to two decimal places. Take $K_{w} = 1.0 \times 1 0^{- 14}$ .

Numerical answer type, answer in x 10^-5, tolerance 0.03.

[H X^{+}] = 1 0^{- 5.45} = 3.548 e - 06

K_{h} = [H X^{+}]^{2} / c = 2.518 e - 10

K_{b} = K_{w} / K_{h} = 3.972 e - 05 = 3.97 \times 1 0^{- 5}