Buffer solutions resist changes in pH when small amounts of acid or base are added. The Henderson-Hasselbalch equation relates pH to the ratio of conjugate base to acid.

Key Formulas:

• pH = pKa + log₁₀([A^-]/[HA])
• Buffer Capacity ≈ 2.303 × C_total × ( [A^-][HA] / ([A^-] + [HA]) )

Units:

• Concentration: mol/L (M), mM, μM, nM
• Amount: mmol, μmol, mol

Applications:

• Biological systems (blood, cells)
• Laboratory and industrial processes
• Pharmaceuticals and food chemistry