Question

A weak monobasic acid has undergone dissociation to the extent of $2\%$ when the concentration is 0.01M at 250C. Calculate the dissociation constant of the acid.

• A.
• B.
• C.
• D.

Answer 1

The correct option is C

$\begin{array}{c}HA\rightleftharpoons H^{+}+A^{-}\\ c(1-\alpha )c\alpha c\alpha \\ 0.01(1.0-0.02)0.01\times 0.020.01\times 0.02\end{array}{K}_B=\frac{c^2{\alpha }^2}{c(1-\alpha )}=\frac{c{\alpha }^2}{1-\alpha }=\frac{0.01\times (0.02{)}^2}{1-0.02}=4.08\times {10}^{-6}$