Ncert Exercises & Solutions

7.51 The degree of ionization of a 0.1 M bromoacetic acid solution is 0.132. Calculate the pH of the solution and the $p K_{a}$ of bromacetic acid.

Degree of ionization, a=0.132

Concentration, c=0.1 M

Thus, the concentration of

$H_{3} O^{+}$ =c.a

$= 0.1 \times 0.132$

$= 0.0132$

$p H = - \log [H^{+}]$

$= - \log (0.0132)$

$= - 1.879 : 1.88$
Now,

$K_{a} = C a^{2}$

$= 0.1 \times {(0.132)}^{2}$

$K_{a} = 0.0017$

$p K_{a} = 2.75$