Buffer capacity of solutions of strong acids.

A strong acid solution can act as a buffer at low pH values. The buffer capacity, β, can be calculated using the following equation:

According to the above equation, the  buffer capacity increases as the hydronium ion concentration increases (pH decreases) in solution. The following table and figure show how buffer capacity of a strong acid changes with pH.

As seen from the table and figure above, the buffer capacity has a relatively large value at lower pH and it gets close to zero at pH values above 3.