NTA Abhyas JEE Main2020ChemistryIonic EquilibriumPractice
The equilibrium constant for : CN - + CH 3 COOH ⇌ HCN + CH 3 COO - is : ( G i v e n p K b f o r C N - = 4.69 a n d p K b f o r C H 3 C O O - = 2.25 )
Options
- A3.7 × 1 0 4
- B2.8 × 1 0 - 5
- C1.97 × 1 0 4
- D0.5 × 1 0 - 5
Correct answer
A. 3.7 × 1 0 4
Step-by-step solution
K eq. = HCN CH 3 COO - CN - CH 3 COOH ; K CH 3 COOH = CH 3 COO - H + CH 3 COOH ; K HCN = H + CN - HCN pK b   of   CN − = 4.69   ∴ pK HCN = 9.31   ;   K HCN = 4.9   × 10 − 10 pK CH 3 COOH = 4.75 ; K CH 3 COOH = 1.77 × 1 0 - 5 ∴ K eq. = K CH 3 COOH K HCN = 1.77 × 1 0 - 5 4.9 × 1 0 - 1 0 = 3.7 × 1 0 4