Question

The ${pK}_a$ of a weak acid, HA, is 4.80. The ${pK}_b$ of a weak base, BOH, is 4.78. What is the pH of an aqueous solution of the corresponding slat BA?

Answer 1

As per the salt hydrolysis formula,

For the salt of weak acid and weak base like $C{H}_{3}COONa$

$K_h=\frac{K_w}{K_a\times K_b}$

$h=\sqrt{\frac{K_w}{K_a\times K_b}}$

$pH=\frac{1}{2}[p{K}_w+p{K}_a–p{K}_b]$

$pH=\frac{1}{2}[14+4.80+4.78]$

$pH=\mathrm{7.01.}$