Ncert Exercises & Solutions

7.50 The degree of ionization of a 0.1M bromoacetic acid solution is 0.132. Calculate the pH of the solution and the pKa of bromoacetic acid.

Degree of ionization, α = 0.132

Concentration, c = 0.1 M

Thus, the concentration of $H_{3} O$ + = c.α

= 0.1 × 0.132

= 0.0132

$pH = - \log [H^{+}] = - \log (0.0132) = 1.879 = 1.88 Now, K_{a} = {Ca}^{2} = 0.1 \times {(0.132)}^{2} K_{a} = . 0017 {pK}_{a} = 2.75$