Spectrophotometric Determination of the Stability Constants of Co(II) and DPKBH (DI-2-Pyridyl Ketone Benzoylhydrazone) |
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| Authors: | M. V. Rossi M. E. V. Suárez-Iha M. R. Hoffmann |
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| Affiliation: | 1. Instituto de Química- B2S- Universidade de S?o Paulo , Cx. Postal 26077 S?o Paulo SP, Brasil , 05599-970;2. Environmental Engineering Science, W. M. Keck Laboratories , California Institute of Technology , Pasadena, California, 91125 |
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| Abstract: | Abstract In order to have more information about the thermodynamic properties of the complexes formed by Cobalt(II) and DPKBH (di-2-pyridyl ketone benzoylhydrazone) and for the development of speciation methods for cobalt, the respective stepwise formation constants were determined in ethanolic solution 50% (V/V), at pH 5.3 and 25.0°C. The spectrophotometric method of corresponding solutions was used and the following overall formation constants were obtained: β1 = 5.305 × 106 M?1 and β2 = 8.476 × 1010 M?2. The molar absorptivities of the 1:1 (ε1) and 1:2 (ε2) complexes (Co(II):DPKBH) were determined to be 4.475 × 10 and 2.994 × 10 (M?1cm?1), respectively. The calculated distribution diagram shows the percentage of the species at equilibrium as a function of the free DPKBH concentration. |
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| Keywords: | Stability Constants Cobalt Di-2-pyridil ketone benzoylhydrazone DPKBH |
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