pH is a measure of
the concentration of H+ [H3O+] ions in a solution. Only the concentration of H+ and
OH- molecules
determine the pH. When the concentration of H+ and OH- ions are equal, the solution is said
to be neutral. If there are more H+ than OH- molecules the solution is acidic, and
if there are more OH- than H+ molecules, the solution is basic.
Buffer
A buffer
solution is one which resists
changes in pH when small
quantities of an acid or an alkali are added to it. An acidic buffer solution is simply one which has a pH less
than 7. Acidic buffer solutions are commonly made from a weak acid and
one of its salts - often a sodium salt.
To be able to add a strong acid or base to a solution
without causing a large change in the pH, we need to create a buffer solution.
A buffer solution contains both a weak acid (HA) and its conjugate base (A-).
A buffer solution (more precisely, pH buffer or hydrogen
ion buffer)
is an aqueous
solution consisting
of a mixture of a weak
acid and
its conjugate
base, or vice versa. Its pH changes very little when a small
amount of strong
acid or base is
added to it. Buffer solutions are used as a means of keeping pH at a nearly
constant value in a wide variety of chemical applications. In nature there are
many systems that use buffering for pH regulation. For example, the bicarbonate buffering system is used to regulate the pH of blood.
