The dissociation constant of acetic is x × 10 – 5 . When 25 mL of 0 . 2 M CH 3 COONa solution is mixed with 25 mL of 0 . 02 M CH 3 COOH solution, the pH of the resultant solution is found to be equal

Question

The dissociation constant of acetic is x × 10 – 5 . When 25 mL of 0 . 2 M CH 3 COONa solution is mixed with 25 mL of 0 . 02 M CH 3 COOH solution, the pH of the resultant solution is found to be equal to 5 . The value of x is _______.

TestHub · Accepted Answer

The Henderson equation for the given acidic buffer can be written as

$pH = pKa + \log \frac{[salt]}{[weak acid]}$

$5 = pKa + \log \frac{25 \times 0.2}{25 \times 0.02} \Rightarrow pKa = 4 \Rightarrow Ka = 10^{- 4} = 10 \times 10^{- 5}$

Hence, the value of $x$ is $10$ .

Chemistry - Ionic Equilibrium Question with Solution | TestHub

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