Page 72 - Pharmaceutical_Analytical_Chemistry_1_Theoretical_Notes_Level_1

Mansoura National University
Pharm D-Clinical Pharmacy Program Level 1 Pharm. Anal. Chem. 1 (PC 101)

CH 3COOH  CH 3COO + H
+
-
+
• If more H is added to this solution, it simply shifts the equilibrium to the
left, absorbing H , so the [H ] remains unchanged.
+
+
+
-
• If H is removed (e.g. by adding OH ) then the equilibrium shifts to the right,
+
releasing H to keep the pH constant.

How a Buffer Works

Basic Buffers

• Ex: mixture of ammonia and ammonium chloride.

+ -
NH + H O  NH + OH
3 2 4
+ -
NH Cl → NH + Cl
4 4

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