Step 1: Understanding the Concept:
Conductance in solution depends on the number and mobility of the ions present. Different ions carry current at different rates, and OH- and H+ are unusually fast movers compared to most other ions because they conduct partly by a proton-hopping mechanism through water.
Step 2: Key Formula or Approach:
Track the ionic composition of the solution through the titration. Before neutralization, acetic acid is only weakly ionized, so conductance starts low. Adding NaOH converts it to sodium acetate, a fully ionized salt of moderate conductance. Once all the acid is consumed, any extra NaOH added does not react with anything, since there is no more acid left.
Step 3: Detailed Explanation:
At the exact neutralization point, the solution contains only sodium acetate and water; both Na+ and acetate ions are present, but with only moderate ionic mobility. Adding more NaOH after this point introduces extra Na+ and, more importantly, extra OH-, and hydroxide ions are among the most mobile ions in aqueous solution. This means every extra drop of NaOH beyond the equivalence point adds ions that conduct especially well, so the conductance climbs sharply rather than leveling off or falling.
Step 4: Final Answer:
Beyond complete neutralization, adding more NaOH increases the conductance, because the highly mobile hydroxide ion is now present in excess.