3. Given the following list of acids and their pKa's:

Acid Formula pKa
hydroflouric acid
HF
3.40
acetic acid
HC2H3O
4.74
hypochlorous acid
HOCl
7.46
hydrocyanic acid
HCN
9.21

Which of the following acid-base conjugate pairs would you choose if you wanted a buffer at pH = 8.30?

a) HF - F-
b) HC2H3O - C2H3-
c) HOCl - OCl-
d) HCN - CN-