When an aqueous solution of a weak monoprotic acid is titrated against a strong base, what mathemati — Ionic Equilibrium Chemistry Question

💡 Solution & Explanation

At the half-neutralization point, exactly half of the weak acid $HA$ has been converted into its conjugate base $A^-$. Therefore, the concentration of the formed salt equals the concentration of the unreacted weak acid ($[Salt] = [Acid]$). According to the Henderson-Hasselbalch equation, $pH = pK_a + \log\frac{[Salt]}{[Acid]}$, which simplifies directly to $pH = pK_a + \log(1) = pK_a$.