Question

$20\, mL$ of $0.2\, M \,NaOH$ is added to $50\, mL$ of $0.2\, M$ acetic acid. The pH of this solution after mixing is $(Ka = 1.8 \times 10^{-5})$

• A. 4.5
• B. 2.3
• C. 3.8
• D. 4

Answer 1

Answer: (A)

4.5

Answer 2

${NaOH + CH3COOH -> CH3COONa + H2O}$
$pH =-\log \left(1.8 \times 10^{-5}\right)+\log \frac{4 / 70}{6 / 70}$
$=4.56$