When a concentrated solution of an electrolyte is diluted

Options

A. its specific conductance increases
B. its equivalent conductivity decreases
C. its specific conductivity decreases and equivalent conductivity increases
D. Both specific and equivalent conductivity increases

Answer

To solve the question regarding the effects of diluting a concentrated solution of an electrolyte, we will analyze the concepts of specific conductance and equivalent conductance step by step.

### Step-by-Step Solution:

1. **Understanding Specific Conductance (κ)**:
- Specific conductance (κ) is a measure of a solution's ability to conduct electricity. It is defined as the conductance (G) of a solution multiplied by the cell constant (L/A), where L is the distance between the electrodes and A is the area of the electrodes.
- The formula for specific conductance is:
\[ κ = \frac{G \cdot L}{A} \]

2. **Effect of Dilution on Specific Conductance**:
- When a concentrated solution is diluted, the volume of the solution increases. This increase in volume leads to an increase in the area of the electrodes that are dipped into the solution (A).
- Since specific conductance is inversely proportional to the area (A), an increase in area will result in a decrease in specific conductance (κ).
- Therefore, we conclude that:
\[ \text{Specific conductance decreases.} \]

3. **Understanding Equivalent Conductance (λ)**:
- Equivalent conductance (λ) is defined as the specific conductance multiplied by a factor that accounts for the dilution of the solution, specifically the normality (N).
- The formula for equivalent conductance is:
\[ λ = \frac{κ \cdot 1000}{N} \]
- Here, normality (N) is related to the concentration of the solution.

4. **Effect of Dilution on Equivalent Conductance**:
- As the solution is diluted, the volume increases, which causes the normality (N) to decrease (since normality is inversely proportional to volume).
- With a decrease in normality (N), and since κ decreases, we need to analyze the relationship:
- If κ decreases and N decreases, the effect on λ depends on the relative changes in κ and N.
- Since N decreases more significantly than κ, the overall effect is that equivalent conductance (λ) increases.
- Therefore, we conclude that:
\[ \text{Equivalent conductance increases.} \]

5. **Final Conclusion**:
- From the analysis, we find that:
- Specific conductance decreases.
- Equivalent conductance increases.
- Thus, the correct answer to the question is that specific conductivity decreases and equivalent conductivity increases.

### Final Answer:
Specific conductivity decreases and equivalent conductivity increases.

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