Pharmacy Study Material

Free pharmacy material Complexometry INTRODUCTION Werner first observed that each atom is surrounded by the maximum number of small which is collectively called as complex. The technique involves the titrating the metal ions with complexing agent which is commonly known as the ligands. The formed coloured complex is used to detect the end point of the titration. PRINCIPLE The main principle is the reaction between the ligand and the metal ion to form a complex. The metal ion acts as Lewis acid and the ligand acts as Lewis base which is the complexing agent: M +2 + Ln (MLn) +2  Examples: Ag + + 2CN − Ag(CN) 2 − Cu +2 + 4NH 3 Cu(NH 3 ) 4 +2 Metal ion + chelating agent or complexing agent metal ligand complex or ligands THEORY Initially the metal ions are solvated that is, they are dissolved in the appropriate solvent and then these solvent ions are replaced by the ions or other solvent molecules to form the complex. The replacing ...