Question

Which of the following buffer pairs would do the best at resisting pH change at a pH of 5?

Select one:

a. H₂PO₄⁻ and HPO₄⁻²

b. CH₃COOH and CH₃COO⁻

c. NH₄⁺ and NH₃

d. There is not enough information to tell.

Answer 1

Answer : b.) CH₃COOH and CH₃COO⁻

Explanation :

the pKa value for CH3COOH is = 4.74 .

H2PO4- pKa = 7.20

NH4+ pKa = 9.26

here for good buffer pH range should be : pH = +/- pKa

so 4.74 to 5.74 it can act as buffer to resist the pH change.