Study Guides/Chemistry/Molar Conductivity Formula
Study Guide · Chemistry

Molar Conductivity Formula in Electrochemistry

In Class 12 Physical Chemistry (Electrochemistry), we study how solutions conduct electricity. An important concept here is Molar Conductivity, which measures the conducting power of all the ions produced by dissolving exactly one mole of an electrolyte in a solution.

Question (Click to Flip)

What is the formula for molar conductivity?

Answer

The formula for molar conductivity is Λm = (κ × 1000) / C, where κ is the specific conductivity and C is the molar concentration of the solution.

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Key Facts

Symbol: Λm (Lambda m).

Formula: Λm = (κ × 1000) / C.

Unit: S cm² mol⁻¹ (Siemens centimeter squared per mole).

Concept: The conducting power of 1 mole of dissolved electrolyte.

The Molar Conductivity Formula

Molar conductivity is represented by the Greek symbol Λm (Lambda m). The mathematical formula is:

Λm = (κ × 1000) / C

Where:

  • Λm: Molar Conductivity (usually expressed in S cm² mol⁻¹).
  • κ (Kappa): Specific Conductivity of the solution (expressed in S cm⁻¹).
  • C: Molarity or Concentration of the solution (expressed in mol L⁻¹).

Understanding the Relationship

  • Why multiply by 1000?: This is a unit conversion factor used because conductivity is measured in cm⁻¹, but molarity is measured in Liters. Multiplying by 1000 converts liters into cm³.
  • Effect of Dilution: Interestingly, as you dilute a solution (decrease its concentration 'C'), its Molar Conductivity (Λm) increases. This is because adding more water gives the ions more freedom to move, and for weak electrolytes, it increases the degree of dissociation.

Questions and Answers

What is the formula for molar conductivity?+

The formula for molar conductivity is Λm = (κ × 1000) / C, where κ is the specific conductivity and C is the molar concentration of the solution.

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