0.025 M CH3COOH is dissociated 9.5%. Hence the pH of the solution is :

0.025 M CH3COOH is dissociated 9.5%. Hence the pH of the solution is :(a) 2.6244 (b) 3.128 (c) 2.988 (d) 2.267

Answer»

Correct Option is : (a) 2.6244

\(CH_3COOH\) is a weak acid.

Ka = \(\frac{C \alpha \times C \alpha}{C(1 - \alpha)}\)

Ka = \(\frac{C \alpha}{(1 - \alpha)}\) ..... \(\alpha << 1\)

\(\implies Ka = C \alpha^2\)

\([H^+] = C \alpha\) ..... [\(\alpha = \frac{9.5}{100}\)]

\([H^+] = 0.025 \times 0.095\)

\([H^+] = 0.002375\)

\(\therefore \ pH = -log [H^+]\)

\(pH = -log [0.002375]\)

\(pH = 2.6244\)

Option : (a) 2.6244