This paper describes rapid and simple spectrophotometric methods for the determination of the stiochiometries and stability constants of cadmium (II) and titanium (IV) complexes of 8- hydroxyquinoline. The methods are based on the formation of complexes of cadmium (II) and titanium (IV) ions with 8-hydroxyquinoline to form light coloured water soluble products at pH 1 and 6 respectively. The products are stable and have wavelength of maximum absorption at 320 nm for Cd(II) and 360 nm for Ti(IV) while the reagent blank showed a negligible absorbance at 220 nm. The 8- hydroxyquinoline has a wavelength of absorption at 280 nm. The composition of the Cd(II) and Ti(IV) complexes with 8-hydroxyquinoline were studied by Job’s continuous variation and Yoe-Jones molar ratio method which revealed 1:2 metal-ligand ratio for the Cd (II) and Ti (IV) complexes . The stability constants and free energies of the complexes for Cd (II) and Ti (IV) were 2.76 X105 and 6.83 X 106 L. mole-1 .cm-1 and – 4.24 and -4.76 kJ/mol respectively.
The negative values of free energies of both complexes show that the reactions were spontaneous, feasible and irreversible. The results obtained are in good agreement with the certified values obtained by previous researchers on similar complexes.