The acid dissociation constant, K, for acetic acid is 1.8x10^-5.

pK = -log(K) = -log(1.8x10^-5) = 4.7

To make a buffer that has a pH of 4.7 what how should [OAc^-] compare to [HOAc]?

[OAc^-] >[HOAc] [OAc^-]=[HOAc] [OAc^-]<[HOAc]