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(Referência obtida automaticamente do Web of Science, por meio da informação sobre o financiamento pela FAPESP e o número do processo correspondente, incluída na publicação pelos autores.)

Time Evolution of the Activation Energy in a Batch Chemical Oscillator

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Autor(es):
Nogueira, Paulo A. [1] ; Oliveira, Hyria C. L. [1] ; Varela, Hamilton [1]
Número total de Autores: 3
Afiliação do(s) autor(es):
[1] Univ Sao Paulo, Inst Quim Sao Carlos, BR-13560970 Sao Carlos, SP - Brazil
Número total de Afiliações: 1
Tipo de documento: Artigo Científico
Fonte: Journal of Physical Chemistry A; v. 112, n. 48, p. 12412-12415, DEC 4 2008.
Citações Web of Science: 10
Resumo

The batch-operated bromate/phosphate/acetone/dual catalyst system was studied at four temperatures between 5 and 35 degrees C. The dynamics was simultaneously followed by potential measurements with platinum and bromide selective electrodes, and spectroscopically at two different wavelengths. By simultaneously recording these four time series it was possible to characterize the dynamics of the sequential oscillations that evolve in time. The existence of three sequential oscillatory patterns at each temperature allowed estimating the activation energies in each case. Along with the activation energy of the induction period, it was possible to trace the time evolution of the overall activation energy at four different stages as the reaction proceeds. The study was carried out for two different sets of initial concentrations and it was observed that the overall activation energy increases as reactants turn into products. This finding was propounded as a result of the decrease in the driving force, or the system's affinity, of the catalytic oxidative bromination of acetone with acidic bromate, as the closed system evolves toward the thermodynamic equilibrium. (AU)

Processo FAPESP: 04/04528-0 - Auto-organização dinâmica na interface sólido-líquido
Beneficiário:Hamilton Brandão Varela de Albuquerque
Linha de fomento: Auxílio à Pesquisa - Apoio a Jovens Pesquisadores