Question

In a solution containing `0.02M CH_(3)COOH` and `0.01M C_(6)H_(5)COOH`. If `K_(CH_(3)COOH)` and `K_(C_(6)H_(5)COOH)` are `1.8xx10^(-5) and 6.4xx10^(-5)` respectively, then calculate the pH of solution.

Answer 1

Correct Answer - 3
`CH_(3)COOH hArr CH_(3)COO^(-)+H^(+)`
`C_(6)H_(5)COOH hArr C_(6)H_(5)COO^(-)+H^(+)`
`[H^(+)]= sqrt(K_(a_(1)).C_(1)+K_(a_(2)).C_(2))`
`= sqrt(1.8xx10^(-5)xx0.02+6.4xx10^(-5)xx0.01)`
`1xx10^(-3)` , `implies pH=3`