Buffers

• Buffers are aqueous solution of mixture of weak acids and their conjugate bases which resist changes in pH when small amounts of acid or base are added.

Handerson Hasselbalch equation

It can be expressed as

Ka = [H⁺] [A^–] / [HA] —–i)

Or, [H⁺] = Ka [HA]/ [A^–]—— ii)

Taking -log on both sides, we get

-log[H⁺] = -logKa – log [HA]/[A^–] —iii)

Substituting -log[H⁺] with pH and -logKa with pK, we have

pH = pK + log[A^–] / [HA] — iv)

Equation (iv) represent the Handerson-Hasselbalch equation.