The acid ionization constant of is . What is the basic dissociation constant of ? — Ionic Equilibrium Chemistry Question

💡 Solution & Explanation

The acid ionization of $\text{Zn}^{2+}$ acts via $\text{Zn}^{2+} + \text{H}_2\text{O} \rightleftharpoons \text{Zn(OH)}^+ + \text{H}^+$, with $K_a = 2.0 \times 10^{-10}$. The conjugate base is $\text{Zn(OH)}^+$. For a conjugate acid-base pair in water, $K_a \times K_b = K_w = 1.0 \times 10^{-14}$. Thus, the basic dissociation constant $K_b = K_w / K_a = 1.0 \times 10^{-14} / (2.0 \times 10^{-10}) = 0.5 \times 10^{-4} = 5 \times 10^{-5}$. Therefore, correct answer is A.