Question

The dissociation constant of weak acid is $2\times {10}^{-2}$. The pH of solution obtained by titrating $0.12$ M, $50$ ml solution of weak acid with $0.06$ M, $50$ ml $NaOH$ is :

Answer 1

$HA+NaOH\to NaA+H_{2}O$.
$0.12\times 500.06\times 50$ 0 0
= 6 mmole =3mmoles
$finally303$

$\Rightarrow HA\rightleftharpoons H^{+}+A^{-}Ka=\frac{2}{100}=\frac{1}{50}$
$\frac{3}{1000}-xx\frac{3}{1000}+x$

$\Rightarrow \frac{1}{50}=\frac{(3/1000+x)x}{(3/1000-x)}$
$x=\frac{1}{100}$
$pH=2$
$AM=2\times 10=20$.