Knowing actual pKa values (examples in the video below) will help in solving acid-base problems quickly. Again, trends are helpful but actual numbers will help us quantify equilibrium constants in individual steps to see if a reaction pathway (mechanism) stands a chance of actually happening. While pKa values are explained by a combination of factors (polarity, anion stability), it is convenient to have a set of numbers that include all of this background for use as a quick tool in problem solving. A more exhaustive list of pKa values will be needed later when we contemplate deprotonating weaker acids such as alkynes and amines.