JEE Advanced 2009Paper 2
- Exam
- JEE Advanced
- Year
- 2009
- Paper
- Paper 2
- Subject
- Chemistry
- Chapter
- Ionic Equilibrium
JEE Advanced 2009 · Paper 2 · Chemistry · Ionic Equilibrium
The dissociation constant of a substituted benzoic acid at 25^ C is...
The dissociation constant of a substituted benzoic acid at is . The of solution of its sodium salt is
Correct answer
8
Step-by-step solution
\text{ The hydrolysis reaction of conjugate base of acid is }
\begin{gathered} A^{-}(a q)+ \mathrm{H} }_{2} \mathrm{O} \longrightarrow \mathrm{HO}^{-}+\mathrm{HA}\\
K_h=\frac{K_w}{K_a}=\frac{10^{-14}}{10^{-4}}=10^{-10}
\end{gathered}
Since, degree of hydrolysis is negligible;
\left[\mathrm{OH}^{-}\right]=\sqrt{K_h C}=10^{-6} \cdotp[\mathrm{OH}]=6