Question

$p{K}_a$ values of acetic acid is 4.75. If the buffer solution contains $0.125\text{M}$ acetic acid and $0.25\text{M}$ sodium acetate. The $pH$ of buffer solution is:

• A. 5.05
• B. 5.5
• C. 4.9
• D. 5.75

Answer 1

The correct option is A 5.05

$pH=p{K}_a+\text{log}\frac{\text{[Salt]}}{\text{[Acid]}}$
$=4.75+\text{log}\left(\frac{0.25}{0.125}\right)=5.05$