1. Tardigrade
  2. Question
  3. Chemistry
  4. A buffer solution is prepared by mixing 10 mL of 1.0 M acetic acid and 20 mL of 0.5 M sodium acetate acid and then diluted to 100 mL with distilled water. If the pKa of CH3COOH is 4.76, what is the pH of the buffer solution prepared ?

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Q. A buffer solution is prepared by mixing 10 mL of 1.0 M acetic acid and 20 mL of 0.5 M sodium acetate acid and then diluted to 100 mL with distilled water. If the $pK_a$ of $CH_3COOH$ is 4.76, what is the pH of the buffer solution prepared ?

Equilibrium

Solution:

The expression for the $pH$ of the acidic buffer solution is as given below.
$pH = pK _{ a }+\log \frac{[\text { Salt }]}{[\text { Acid }]}$
$pK _{ a }=4.76$
[Salt] $=\frac{20 \times 0.5}{100}=0.1 M$
[Acid] $=\frac{10 \times 1}{100}=0.1 M$
Substitute values in the above equation.
$pH =4.76+\log \frac{0.1}{0.1}=4.76$