Question

The pH of 0.02M weak monobasic acid is 2.52. What is it's degree of dissociation and dissociation constant?

Answer 1

$HX\rightleftharpoons H^{+}+X^{-}$

Given,

$pH=2.52$

$\Rightarrow \left[H^{+}\right]={10}^{-2.52}=3\times {10}^{-3}$

$\alpha =\frac{\left[H^{+}\right]}{C}=\frac{3\times {10}^{-3}}{0.02}=0.151$

$K_c=\frac{C{\alpha }^2}{1-\alpha }$

$\Rightarrow K_c=\frac{0.02\times {0.151}^2}{1-0.151}=5.37\times {10}^{-4}$