Chemical And Ionic Equilibrium Result Question 52
52. The dissociation constant of a substituted benzoic acid at $25^{\circ} \mathrm{C}$ is $1.0 \times 10^{-4}$. The $\mathrm{pH}$ of $0.01 \mathrm{M}$ solution of its sodium salt is
(2009)
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Answer:
Correct Answer: 52. $( 8 )$
Solution:
- The hydrolysis reaction is
$ \begin{gathered} A^{-}+\mathrm{H}_2 \mathrm{O} \rightleftharpoons A \mathrm{H}+\mathrm{OH}^{-} \\ K_h=\frac{K_w}{K_a}=10^{-10} \\ {\left[\mathrm{OH}^{-}\right]=\sqrt{K_h C}=10^{-6}} \\ \mathrm{pOH}=6 \text { and } \mathrm{pH}=8 \end{gathered} $
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