Chemistry
How Buffer Capacity Varies with pH and Concentration
Quick fact
A buffer has maximum capacity when its pH equals its pKa, and the capacity decreases by 50% for every unit of pH away from the pKa. Also, doubling the total concentration of the buffer components doubles the buffer capacity.
Why this is interesting
Why does a tiny amount of acid completely change the pH of water, but barely affect a buffer? And why does the same buffer suddenly lose its power after a certain point?