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Química Nova

Print version ISSN 0100-4042

Abstract

TOKORO, Gustavo; OLIVEIRA, Hyrla C. L.  and  VARELA, Hamilton. Complex Dynamics in the bromate/hypophosphite/acetone/manganese and ferroin system. Quím. Nova [online]. 2007, vol.30, n.8, pp. 1930-1937. ISSN 0100-4042.  http://dx.doi.org/10.1590/S0100-40422007000800026.

New chemical systems have been recently designed for the study of complex phenomena such as oscillatory dynamics in the temporal domain and spatiotemporal pattern formation. Systems derived from oscillators based on the chemistry of bromate are the most extensively studied, with the celebrated Belousov-Zhabotinsky (BZ) reaction being the most popular example. Problems such as the formation of bubbles (CO2) and solid precipitate in the course of the reaction and the occurrence of simply short-lived oscillations under batch conditions are very common and, in some cases, compromise the use of some of these systems. It is investigated in this paper the dynamic behavior of the bromate/hypophosphite/acetone/dual catalyst system, which has been sugested as an interesting alternative to circumvent those inconvenients. In this work, manganese and ferroin are employed as catalysts and the complete system (BrO3-/H2PO2 -/acetone/Mn(II)-ferroin) is studied under batch conditions. Temporal symmetry breaking was studied in a reactor under agitation by means of simultaneous records of the potential changes of platinum and Ag/AgBr electrodes, both measured versus a reversible hydrogen electrode. Additionally, spatio-temporal formation of target patterns and spiral waves were obtained when the oscillating mixture was placed in a quasi two-dimensional reactor.

Keywords : oscillations; chemical kinetics; pattern formation.

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