Based on Henderson - Hasselbach equation, we have
pH = pka + log [tex] \frac{[Acid]}{\text{[conjugate base]}} [/tex]
Given: pH = 5.28 and [Acid] = 0.05 m,
∴ pKa = 5.28 - log (0.05) = 6.58
∴ Ka = 2.624 X [tex] 10^{-7} [/tex]
Thus, ionization constant of boric acid is 2.624 X [tex] 10^{-7} [/tex]
