| Abstract: | The complex formation of lead with Bromopyragallol Red has been studied spectrophotometrically in an attempt to establish composition, stability, thermodynamic parameters and optimum condition for determining small amounts of lead. The blue complex of lead had λmax at 630 nm (against a reagent blank). The composition as determined by different methods is 1:1 at pH 5.5±0.1. The mean value of log K, free energy (ΔG), the heat content (ΔH) and entropy change (ΔS) of the complex are found to be 6.28, ?10.46 kcal/mole and 6.31 e. u. respectively at 25°C. The molecular extinction coefficient and Sendall's sensitivity is 5000 and 0.0140 μg of lead/cm2. The effect of diverse ions was examined with eighteen cations and ten anions, in the determination of lead. |
