Kinetic Study of the Reduction of Bromate Ion by Tris(1,10-Phenanthroline)Iron(II) and Aquoiron(II) Ions — Implication for the Bromate-Gallic Acid Oscillating Reaction |
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Authors: | Jing-Jer Jwo Eng-Fen Chang |
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Abstract: | The kinetics of the bromate oxidation of tris(1,10-phenanthroline)iron(II) (Fe(phen)32+) and aquoiron(II) (Fe2+ (aq)) have been studied in aqueous sulfuric acid solutions at μ = 1.0M and with Fe(II) complexes in great excess. The rate laws for both reactions generally can be described as -d [Fe(II)]/6dt = d[Br?]/dt = k[Fe(II)] [BrO?3] for [H+]0 = 0.428–1.00M. For [BrO?3]0 = 1.00 × 10?4M. [Fe2+]0 = (0.724–1.45)x 10?2 M, and [H+]0 = 1.00M, k = 3.34 ± 0.37 M?1s?1 at 25°. For [BrO?3]0 = (1.00–1.50) × 10?4M, [Fe2+]0 = 7.24 × 10?3M ([phen]0 = 0.0353M), and [H+]0 = 1.00M, k = (4.40 ± 0.16) × 10?2 M?1s?1 at 25°. Kinetic results suggest that the BrO?3-Fe2+ reaction proceeds by an inner-sphere mechanism while the BrO?3-Fe(phen)32+ reaction by a dissociative mechanism. The implication of these results for the bromate-gallic acid and other bromate oscillators is also presented. |
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Keywords: | Bromate oxidation tris(1,10-phenanthroline)-iron(II) and aquoiron(II) ions |
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