Question

pK_b of CH₃COO^– ion is 9.26. pH of a solution when 0.01 M CH₃COOH is neutralized 50% and at equivalent point using 0.01 M NaOH are respectively:

(a) 4.63, 8.22 

(b) 4.74, 8.22

(c) 2.37, 4.11 

(d) 4.74, 8.37

Answer 1

Correct option: (b) 4.74, 8.22

Explanation: 

At 50% neutralization,

[CH₃COOH] = [CH₃COONa]

pH = pK_a = 4.74

(pK_a = 14 – pK_b)

At complete neutralization CH₃COONa solution is alkaline due to hydrolysis and conc. is halved due to dilution by equal volume of NaOH