For a typical conjugate acid-base pair represented as and , which of the following exact algebraic i — Ionic Equilibrium Chemistry Question

💡 Solution & Explanation

The relationship between dissociation constants of a conjugate pair is $K_a \cdot K_b = K_w$. At $25^\circ C$, $K_w = 10^{-14}$, thus $pK_a + pK_b = 14$. The base dissociation expression for $A^-$ is indeed $A^- + H_2O \rightleftharpoons HA + OH^-$, yielding $K_b = \frac{[HA][OH^-]}{[A^-]}$. Finally, a stronger acid means a higher $K_a$, which mathematically forces a lower $pK_a$. Since $pK_a + pK_b = 14$, a lower $pK_a$ strictly results in a higher $pK_b$ (weaker conjugate base).