Question

The chloride salt of a certain weak monoacidic organic base is hydrolysed to an extent of $3$% in its $0.1M$ solution at ${25}^{o}C$. Given that the ionic product of water is ${10}^{-14}$ at this temperature, what is the dissociation constant of the base?

• A. $\approx 1\times {10}^{-10}$
• B. $\approx 1\times {10}^{-9}$
• C. $\approx 3.33\times {10}^{-9}$
• D. $\approx 3.33\times {10}^{-10}$

Answer 1

Answer: (A)

$\approx 1\times {10}^{-10}$

$h=0.03$, $C=0.1M$ , $K_w={10}^{-14}$

We know, $K_a=C{h}^2$

$\frac{K_w}{K_b}=C{h}^2\Rightarrow \frac{{10}^{-14}}{K_b}=\left(0.1\right)(0.03{)}^2\Rightarrow \frac{{10}^{-9}}{9}\approx 1\times {10}^{-10}$