Chemistry - Electrochemistry Question with Solution | TestHub
Which of the following plots will obtained for a conductmetric titration of stong acid against a weak base-
Options:
Answer:
Solution:
1. Initial stage (before equivalence point): A strong acid (e.g., HCl) has high conductivity due to H⁺ ions. As a weak base (e.g., NH₄OH) is added, H⁺ ions react to form water and a salt (e.g., NH₄Cl).
The highly mobile H⁺ ions are replaced by less mobile NH₄⁺ ions, leading to a decrease in conductivity.
2. Equivalence point: At the equivalence point, most of the strong acid has reacted. The solution contains the salt of a strong acid and a weak base (e.g., NH₄Cl) and water. The conductivity is at its minimum.
3. After equivalence point: Adding excess weak base (NH₄OH) beyond the equivalence point causes a slight increase in conductivity. This is because NH₄OH is a weak electrolyte and dissociates only slightly:
The increase in ions is minimal compared to the initial decrease or the increase seen with a strong base.
Therefore, the plot shows an initial sharp decrease, followed by a relatively flat or slightly increasing region after the equivalence point. This corresponds to option C.
