Question

As the solution of a strong electrolyte is diluted the following phenomenon is observed:

• A. The specific conductance decrease and equivalent conductance increases
• B. The specific conductance increases and equivalent conductance decreases
• C. Both specific conductance and equivalent conductance increase
• D. Both specific conductance and equivalent conductance decrease

Answer 1

The Correct Option is A

To understand the behavior of specific conductance and equivalent conductance when a strong electrolyte solution is diluted, let's delve into the concepts of conductance in solutions:

Concept Explanation

• Specific Conductance (K): It is the measure of a solution's ability to conduct electricity. It is defined as the conductance of a solution in a one-centimeter cube. Specific conductance is dependent on the concentration of ions in the solution. More ions result in higher specific conductance. Therefore, as a solution is diluted and the number of ions per unit volume decreases, the specific conductance decreases.
• Equivalent Conductance (Λ_eq): This is the conductance of all the ions produced by dissolving one equivalent of an electrolyte in a solution. Equivalent conductance accounts for the increase in volume available per ion upon dilution, which enhances the ions' mobility. As dilution increases, the number of ions per unit volume decreases, but each ion moves more freely, leading to an increase in equivalent conductance.

Explanation of the Observations

Upon dilution, the concentration of ions per unit volume decreases, leading to the following observations:

1. The Specific Conductance decreases because there are fewer ions available to conduct electricity in a given volume.
2. The Equivalent Conductance increases because the ions have more space (due to the larger volume) to move freely, increasing their mobility and thus the overall conductance per equivalent of electrolyte.

These explanations align with Kohlrausch's Law, which states that at infinite dilution, the equivalent conductance of an electrolyte is the sum of the equivalent conductances of its isolated ions.

Conclusion

Based on these principles, the correct answer to the question is: The specific conductance decreases and equivalent conductance increases.