The dissociation constant of acetic is x × 10 ^ – 5 . When 25mLof0...

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

$pH = pKa + log\dfrac{\left[salt\right]}{\left[weakacid\right]}$

$5 = pKa + log\dfrac{25 \times 0 . 2}{25 \times 0 . 02} ⇒ pKa = 4 ⇒ Ka = {10}^{- 4} = 10 \times {10}^{- 5}$

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