The first point to be noted is that if AH and A– are present in equal quantities, pH = pKa. Secondly,
when the pH of the solution is in the range pKa ± 1, relatively large changes in αAH or αA– correspond to
small changes in pH. To put this another way, the solution can tolerate quite large changes in its
composition whilst the pH is maintained almost constant. When this situation exists the solution is said
to be buffered and the solution is known as a buffer solution.
Buffers and pH Control
It is often necessary to control the pH of a solution in circumstances where hydrogen ions are being
generated or absorbed. The buffer solution