Question

If the molar conductivity (Λ_m) of a 0.050 mol L⁻¹ solution of a monobasic weak acid is 90 S cm² mol⁻¹, its extent (degree) of dissociation will be ______.

[Assume `Λ_+^°` = 349.6 S cm² mol⁻¹ and `Λ_-^°` = 50.4 S cm² mol⁻¹.]

विकल्प

• 0.115

• 0.125

• 0.225

• 0.215

Answer 1

If the molar conductivity (Λ_m) of a 0.050 mol L⁻¹ solution of a monobasic weak acid is 90 S cm² mol⁻¹, its extent (degree) of dissociation will be 0.225.

Explanation:

Given: Molar conductivity (Λ_m) = 90 S cm² mol⁻¹

Limiting molar conductivity of cation `(Λ_+^°)` = 349.6 S cm² mol⁻¹

Limiting molar conductivity of anion `(Λ_-^°)` = 50.4 S cm² mol⁻¹

Concentration (c) = 0.050 mol L⁻¹

`Λ_m^° = Λ_+^° + Λ_-^°`

= 349.6 + 50.4

= 400 S cm² mol⁻¹

Degree of Dissociation (α) =`(Λ_m)/(Λ_m^°)`

= `90/400`

= 0.225