When visually examining the titration curve of a solution titrated with a solution, which of the fol — Ionic Equilibrium Chemistry Question

💡 Solution & Explanation

The titration of $Na_2CO_3$ with $HCl$ involves a diprotic base. It accepts protons in two separate stages: first to form $NaHCO_3$, and second to form $H_2CO_3$. Visually, the titration curve will display two distinct flat buffer regions (one for $CO_3^{2-}/HCO_3^-$ and one for $HCO_3^-/H_2CO_3$), separated by two distinct vertical equivalence point drops. The first equivalence point corresponds to the formation of $NaHCO_3$, which is an amphiprotic salt with a pH $\approx (pK_{a1}+pK_{a2})/2 \approx 8.3$, not 7.0.