A chemist plots a titration curve tracing the pH of a solution as is continuously added to of . Visu — Ionic Equilibrium Chemistry Question
Question
A chemist plots a titration curve tracing the pH of a solution as $0.1 \text{ M } HCl$ is continuously added to $50 \text{ mL}$ of $0.1 \text{ M } NH_4OH$. Visually, the curve begins at a high pH, displays a buffer region, and then plummets vertically. Where will the sharp, vertical equivalence point visual drop be centered on the pH axis?
💡 Solution & Explanation
The visual titration curve of a weak base ($NH_4OH$) against a strong acid ($HCl$) starts high (basic), gradually drops through a basic buffer region ($NH_4OH/NH_4^+$), and undergoes a sharp, steep visual drop at the equivalence point. Because the resulting salt ($NH_4Cl$) undergoes cationic hydrolysis, the solution at the exact equivalence point is acidic. Therefore, the vertical drop is centered in the acidic region (typically around pH 5).