Question

The dissociation constant of a acetic acid at ${25}^{\circ }C$ is $1.0\times {10}^{-4}$. The pH of $0.01M$ solution of its sodium salt is

• A. 6
• B. 7
• C. 8
• D. 9

Answer 1

The correct option is C 8

Given $K_a={10}^{-4}$
$\therefore p{K}_a=4$
Concentration of the solution is $C=0.01M$
For a salt of weak acid and strong base,
$\therefore pH=7+\frac{1}{2}p{K}_a+\frac{1}{2}\text{log C}=7+\frac{1}{2}\left(4\right)+\frac{1}{2}(-2)=8$