Kinetics of the Formation of the Blue Complex CrO(O2)2 Formed by Dichromate and H2O2 in Acid Solutions. A Stopped-Flow Investigation Using Rapid-Scan UV-VIS Detection |
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| Authors: | Günter Grampp Stephan Landgraf Tomasz Wesierski Beata Jankowska Ewa Kalisz Dana-Maria Sabou Boryana Mladenova |
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| Institution: | (1) Graz University of Technology, Institute of Physical and Theoretical Chemistry, A-8010 Graz, Austria, AT;(2) A. Mickiewicz University, Faculty of Chemistry, Dept. of Physical Chemistry, Poznan, Poland, PL;(3) “Babes-Bolyai” University Cluj-Napoca, Faculty of Chemistry, Dept. of Physical Chemistry, Cluj, Romania, RO;(4) Bulgarian Academy of Science, Institute of Catalysis, EPR-Laboratory, Sofia, Bulgaria, BG |
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| Abstract: | Summary. The kinetics of the CrO(O2)2 formation by H2O2 and Cr2O7
2− in aqueous acidic media was measured at 293 ± 2 K in a pH range between 2.5 and 3.3. Using the stopped-flow method with rapid scan UV-VIS detection, the rate law of the formation
of CrO(O2)2 was determined. For the media HClO4, HNO3 and CH3COOH, the reaction order in the Cr2O7
2− concentration was found to be 0.5. For H2O2] as well as for H+], the reaction was first order in all acids used. In HCl and H2SO4 media the reaction was first order in Cr2O7
2−. At T = 293 ± 2 K the rate constant for the formation of Cr(O)(O2)2 was found to be (7.3 ± 1.9) · 102 M−3/2 s−1 in HClO4.
Corresponding author. E-mail: grampp@ptc.tu-graz.ac.at
Received January 30, 2002; accepted (revised) June 5, 2002 |
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| Keywords: | , ,Chemical kinetics, Stopped-flow technique, Cr(O)(O2)2 complex, Reaction order |
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