Which of the following graph truly represents the titration of solution against solution? — Electrochemistry Chemistry Question

💡 Solution & Explanation

\textbf{Conductometric Titration of HCl vs NaOH} \textbf{Initial solution:} HCl (strong acid, fully dissociated) - High conductance due to H$^+$ ions ($\lambda^\circ_m(\text{H}^+) \approx 350\ \text{S cm}^2\text{mol}^{-1}$) \textbf{During titration (before equivalence point):} As NaOH is added: \[ \text{H}^+ + \text{OH}^- \rightarrow \text{H}_2\text{O} \] The highly mobile H$^+$ ions ($\lambda \approx 350$) are replaced by much less mobile Na$^+$ ions ($\lambda \approx 50$). \textbf{Result: Conductance decreases sharply.} \textbf{At equivalence point:} Solution contains only NaCl. Minimum conductance. \textbf{After equivalence point:} Excess NaOH is added. OH$^-$ ions ($\lambda^\circ \approx 200$) are added to solution. \textbf{Result: Conductance rises steeply.} \textbf{Shape of graph:} A clear \textbf{V-shaped curve} — falling before the equivalence point and rising sharply after. The \textit{equivalence point} is located at the \textbf{minimum (vertex)} of the V. \textbf{Answer:} Select the graph showing a \textbf{V-shape} with the minimum exactly at the equivalence point.