Question

Calculate the pH of a solution that is 0.291 M acetic acid and 0.123 M sodium acetate. The Ka of acetic acid is 1.76×10^–5 at 25°C. What is the pH of this mixture at 0°C?

Answer 1

Answer:

The answer is "4.37."

Explanation:

at $0^{\circ} C\ Ka = 1.76 \times 10^{-5}$

$\to pKa = - \log \ Ka$

            $= - \log \ 1.76 \times 10^{-5}\\\\ = 4.75$

$pH = pKa + \log \frac{[sodium \ acetate]}{[acetic \ acid]}$

      $= 4.75 + \log \frac{[0.123]}{[0.291]}\\\\= 4.75+ \lg(0.422680412)\\\\=4.75-0.373987878\\\\=4.37601212\\\\=4.37$