Question

Calculate pH of a solution of given mixture (0.1 mole ${CH}_{3}COOH+0.2mole{CH}_{3}COONa$) in 100 ml 0f mixture. $K=2\times {10}^{-5}$

• A. 4.6
• B. 5
• C. 6.6
• D. 7.6

Answer 1

The correct option is B 5

acid $=0.1mol$

base $=0.2mol$

$\therefore$ for buffer,

$pH=pKa+\log \frac{\left[base\right]}{\left[acid\right]}$

$=5-\log 2+\log \frac{0.2/v}{0.1/v}$

$=5-\log 2+\log 2$

$=5$

$\therefore pH=5$