Step 1: What is conductometric titration?
Conductometric titration measures the electrical conductance of a solution as a titrant is added. Conductance depends on the concentration and mobility of ions in the solution. As the titration proceeds, ion composition changes, and so does the conductance.
Step 2: How is the endpoint detected?
The endpoint is identified by plotting conductance against volume of titrant added. There is a sharp change in conductance at the equivalence point, forming a V-shape or a distinct break in the graph. This break is the endpoint.
Step 3: Why not the other options?
Colour change is used in indicator-based titrations. pH jump is the basis of potentiometric titration. Potential difference is measured in potentiometric methods, not conductometric ones.
Step 4: Advantage of conductometric titration.
It can be used with coloured or turbid solutions where visual colour indicators would fail. The endpoint is precise and objective.
Step 5: Confirm.
The endpoint in conductometric titration is detected by a sharp change in conductance of the solution at the equivalence point.
Answer: Option (2) — Sharp change in conductance