BUFFER SOLUTIONS

The solutions which resist charge in pH on dilution or with addition of small amounts of acid or alkali are called buffer solutions.

 e.g. CH3COOH + CH3COONa

H2CO3 + HCl

Acidic Buffer: Weak acid and its salt with strong base are known as acidic buffer pH < 7.

e.g CH3COOH and CH3COONa, H2CO3 and HCl

Basic Buffer: Weak base and its salt with strong acid are known as basic buffer. pH > 7

e.g. NH4Cl and NH4OH

  • pOH of a basic buffer = pKb +  log ([salt]/[acid])
  • pH of a basic buffer = pKa – log ([salt]/[acid])