Acids and Bases - Buffers

Question

Buffer Systems Operate In A Roughly 2.0 PH Unit Range, Centered Around What Value? (Hint: Think Henderson-Hasselbalch Equation.)

Answer 1

The Henderson-Hasselbalch equation is:

pH = pK + log [conjugate base]/ [acid]

If the concentration of the acid is equal to the concentration of the conjugate base, the pH is equal to the pK value. If the base to acid ratio is 10:1, the pH would be pK + 1. If the acid to base ratio is 10:1, the pH would be pK - 1. The range of pH values would then be 2 (pK +1 to pK -1).