For weak electrolytes, the degree of dissociation (α) is calculated using the formula:

α = Λ_m / Λ⁰_m

Where:

• Λ_m: Observed molar conductivity at given concentration
• Λ⁰_m: Limiting molar conductivity (at infinite dilution)

Limiting Molar Conductivity

For a monobasic acid:

Λ⁰_m = Λ⁰₊ + Λ⁰₋

Given:

• Λ⁰₊ = 349.6 S·cm²·mol⁻¹ (for H⁺)
• Λ⁰₋ = 50.4 S·cm²·mol⁻¹ (for A⁻)

Total:

Λ⁰_m = 349.6 + 50.4 = 400.0 S·cm²·mol⁻¹

Observed Molar Conductivity

At concentration 0.050 M:

Λ_m = 90 S·cm²·mol⁻¹

Calculation of Degree of Dissociation

α = 90 / 400 = 0.225

Therefore, the degree of dissociation (α) is 0.225.