So from this equation we see that if this is true, only then will the PH equal to the PKA. So once again, from this previous graph, we basically describe the Titration curve for the buffer system in which we have acetic acid as that acid and acetate ion as the conjugate base. Now, the PKA value of acetic acid is 4.75. And notice that when the PH of the solution is 4.75, which is the same as the PKA, the curve has the flattest slope, and the flattest slope corresponds to the region with the least change in PH. So what do we conclude from this discussion? Well, basically, buffer functions best at PH values that correspond to the PKA of that asset that we're using in the first place.