Q. For strong electrolyte Λ_m increases slowly with dilution and can be represented by the equation

Λ_m = Λ^°_m − Ac^1/2

Molar conductivity values of the solutions of strong electrolyte AB at 18°C are given below :

The value of constant A based on the above data [in S cm² mol⁻¹ /(mol/L)^1/2] unit is ________.

Correct Answer: 4

Explanation

For a strong electrolyte, the molar conductivity follows the relation:

Λ_m = Λ^°_m − A√c

Using two given data points:

For c = 0.04 mol L⁻¹, √c = 0.2 and Λ_m = 96.1

For c = 0.25 mol L⁻¹, √c = 0.5 and Λ_m = 94.9

Difference in molar conductivity:

96.1 − 94.9 = 1.2

Difference in √c:

0.5 − 0.2 = 0.3

Hence, the value of constant A is:

A = 1.2 / 0.3 = 4

Therefore, the value of constant A is 4.

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