Question

The $pH$ of solution containing $0.10\, M$ sodium acetate and $0.03\, M$ acetic acid is $\left( pK _{a} \text { for } CH _{3} COOH =4.57\right)$

• A. 4.09
• B. 6.09
• C. 5.09
• D. 7.09

Answer 1

Answer: (C)

5.09

Answer 2

According to Henderson's equation, $p H=p_{K a}+\log \frac{[\text { salt }]}{[\text { acid }]}$ $CH _{3} COOH + NaOH \rightarrow CH _{3} COONa + H _{2} O$ Putting the values, we get: $p H=4.57+\log \frac{0.10}{0.03}$ $\Rightarrow p H=5.09$