A good buffer generally contains relatively equal concentrations of weak acid and conjugate base. If you wanted to buffer a solution at pH = 4.00 or pH = 10.00, how would you decide which weak acid– conjugate base or weak base–conjugate acid pair to use? The second characteristic of a good buffer is good buffering capacity. What is the capacity of a buffer? How do the following buffers differ in capacity? How do they differ in pH?

0.01 M acetic acid/0.01 M sodium acetate

0.1 M acetic acid/0.1 M sodium acetate

1.0 M acetic acid/1.0 M sodium acetate