Target Exam

CUET

Subject

Chemistry

Chapter

Physical: Electro Chemistry

Question:

Select the relation which correctly relates the variation of $Λ_m$ with concentration for strong electrolytes.

Options:

$Λ_m=Λ_m-Ac$

$Λ_m=Λ_m-Ac^{\frac{1}{2}}$

$Λ_m=Λ_m+Ac^{\frac{1}{2}}$

$Λ_m=Λ_m-Ac^{\frac{3}{2}}$

Correct Answer:

$Λ_m=Λ_m-Ac^{\frac{1}{2}}$

Explanation:

The correct answer is Option (2) → $Λ_m=Λ_m-Ac^{\frac{1}{2}}$

The variation of molar conductivity ($\Lambda_m$) with concentration ($c$) for strong electrolytes is correctly described by the Debye-Hückel-Onsager equation (often referred to in this context as the Kohlrausch equation).

The correct relation is:

☀ $\Lambda_m = \Lambda_m^\circ - Ac^{1/2}$

Explanation of the Terms

This equation shows a linear relationship between molar conductivity and the square root of the concentration:

  • $\Lambda_m$: Molar conductivity at a specific concentration $c$.
  • $\Lambda_m^\circ$: Limiting molar conductivity (molar conductivity at infinite dilution, where $c \to 0$).
  • $A$: A constant that depends on the type of electrolyte, the nature of the solvent, and the temperature.
  • $c^{1/2}$: The square root of the molar concentration ($\sqrt{c}$).