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