Answer Happy

I am trying to understand the reactions of amines and their pKa dealing with the pH level when react with water. my question is, if the product of the reaction has a pKa of 4 for instance, and the pH level is a 4, this would be equal, 50%-50% ratio, if the pH is at a 5, its less acidic, less protanated. I'm trying to understand that the concept works for any pKa level?