which of the following plots will obtained for a conductometric titration of strong acid against a weak base?

Options

A. (a)
B. (b)
C. (c)
D. (d)

Answer

To determine the plot obtained for a conductometric titration of a strong acid against a weak base, we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Components**:
- We are titrating a strong acid (e.g., HCl) with a weak base (e.g., NH4OH).
- Strong acids completely dissociate in solution, providing a high concentration of H⁺ ions.
- Weak bases partially dissociate, leading to a lower concentration of OH⁻ ions.

2. **Initial Conductance**:
- At the start (when the volume of the weak base is zero), the solution contains only H⁺ ions from the strong acid.
- The conductance is high due to the presence of these highly mobile H⁺ ions.

3. **Adding the Weak Base**:
- As we begin to add the weak base, the OH⁻ ions will react with the H⁺ ions to form water.
- This reaction reduces the concentration of H⁺ ions, leading to a decrease in conductance.

4. **Equivalence Point**:
- At the equivalence point, all H⁺ ions have reacted with OH⁻ ions.
- The conductance reaches its minimum because the solution now contains only the salt formed and water, which has lower conductivity compared to the initial acid solution.

5. **Post-Equivalence**:
- After the equivalence point, as we continue to add more weak base, the concentration of OH⁻ ions begins to increase.
- However, since the weak base only partially dissociates, the increase in conductance will be gradual and will eventually level off, resulting in a nearly constant conductance after a certain volume of the weak base has been added.

6. **Final Plot**:
- The plot will start high (due to H⁺ ions), decrease to a minimum at the equivalence point, and then level off as more weak base is added.

### Conclusion:
The correct plot for the conductometric titration of a strong acid against a weak base will show:
- High conductance at zero volume of the base.
- A decrease in conductance as the base is added, reaching a minimum at the equivalence point.
- A gradual increase in conductance that levels off after the equivalence point.

Thus, the correct answer is **Plot C**.