Question

The dissociation constants for aniline, acetic acid and ionic product of water at $25^{\circ }C$ are $3.83\times 10^{-10},1.75$ $\times 10^{-5}$ and $1.008\times 10^{-14}$ respectively. The degree of hydrolysis of aniline acetate in a decinormal solution is

• A. $0.56\%$
• B. $55\%$
• C. $5.6\%$
• D. $2.75\%$

Answer 1

Answer: (B)

Let the concentration of salt be $C$ mol $li{t}^{-1}$
$K_h=\frac{\left[C_6{H}_{5}N{H}_2\right]\left[C{H}_{3}COOH\right]}{\left[C_6{C}_{5}N{H}_3^{+}\right]\left[C{H}_{3}CO{O}^{-}\right]}$
$=\frac{C^2{h}^2}{C^2(1-h)(1-h)}=\frac{h^2}{(1-h{)}^2}$
$\sqrt{K_h}=\frac{h}{(1-h)}$
Or $\left(\frac{h}{1-h}\right)=\sqrt{K_h}=\sqrt{\frac{K_w}{K_a\cdot K_b}}$
$=\sqrt{\frac{1.008\times 10^{-14}}{1.75\times 10^{-5}\times 3.83\times 10^{-10}}}$
$=\sqrt{\frac{1.008\times 10}{1.75\times 3.83}}=\sqrt{\frac{10.08}{6.7025}}=\sqrt{1.5039}$
$\left(\frac{h}{1-h}\right)=1.23$
or $h=0.55$
$h=0.55$
or $55\%$