The salt BA is formed from a weak acid HA (K_a = 2.0x10^-5) and a weak base BOH (K_b = 1.6x10^-5). Use K_h = K_w/(K_a K_b) and h = sqrtK_h (valid when h ll 1). Find the percentage hydrolysis of the salt in water, to two decimal places.

JEE Main levelNumerical answerDifficulty 2 of 3ia011

The salt $BA$ is formed from a weak acid HA ( $K_{a} = 2.0 \times 1 0^{- 5}$ ) and a weak base $BOH$ ( $K_{b} = 1.6 \times 1 0^{- 5}$ ). Use $K_{h} = K_{w} / (K_{a} K_{b})$ and $h = K_{h}$ (valid when $h ≪ 1$ ). Find the percentage hydrolysis of the salt in water, to two decimal places.

Numerical answer type, answer in %, tolerance 0.01.

K_{h} = 1 0^{- 14} / (2.0 \times 1 0^{- 5} \times 1.6 \times 1 0^{- 5}) = 3.125 e - 05

h = K_{h} = 0.00559

, which is independent of concentration. Percentage hydrolysis

= 0.56%