NEET2021ChemistryElectrochemistryActual
The molar conductivity of 0 . 007   M acetic acid is 20   S   cm 2   mol - 1 . What is the dissociation constant of acetic acid? Choose the correct option. λ H + ∘ = 350   S   cm 2   mol - 1 λ CH 3 COO - ∘ = 50   S   cm 2   mol - 1
Options
- A1 . 75 × 10 - 4   mol   L - 1
- B2 . 50 × 10 - 4   mol   L - 1
- C1 . 75 × 10 - 5   mol   L - 1
- D2 . 50 × 10 - 5   mol   L - 1
Correct answer
C. 1 . 75 × 10 - 5   mol   L - 1
Step-by-step solution
λ CH 3 COOH ∘ = λ CH 3 COO - ∘ + λ H + ∘ λ CH 3 COO - ∘ = 350 + 50 = 400   S   cm 2   mol - 1 λ CH 3 COOH = 20 Scm 2   mol - 1 given α = λ CH 3 COOH λ CH 3 COOH ∘ = 20 400 = 5 × 10 - 2 K a = cα 2 = 0 . 007 × 5 × 10 - 2 2 = 1 . 75 × 10 - 5   molL - 1