The kinetics of oscillating reactions. Laboratory experiment for physical chemistry

Dynamical regime of resorcinol based Belousov–Zhabotinsky chemical oscillator in the presence or absence of some hydrophobic antioxidants in aqueous–organic mixed media

“…[11][12][13]15 From the available knowledge on these reactions, it follows that the system must be far from thermodynamic equilibrium i.e., DG must be large and negative, which entails using a well stirred continuous-ow reactor (CSTR), 14,[16][17][18] and that one or more autocatalytic or cross-catalytic steps must take place between two steps of the reaction mechanism. 19 Although some oscillating reactions have been used for analytical purposes, particularly the Ce 4+ -catalyzed reaction between malonic acid and KBrO 3 , known as BZ reaction, 20,21 analytical determinations based on a closed system including the analyte involve labour-intensive procedures that entail re-starting the oscillating system before each new determination. This accounts for the little interest aroused so far by this type of reaction for analytical purposes.…”

Critical ReviewApproaching the use of oscillating reactions for analytical monitoring

“…The fluctuations are reflected in colour changes (if the oscillating species exhibit different colours), pH changes (variations in the H + or OH 2 concentration in the medium), redox potential changes, etc. For a chemical reaction to be the source of an autooscillating system, at least the following requirements must be met: 8 (a) the system should be far from thermodynamic equilibrium, i.e., its Gibbs free energy difference (DG) should be large and negative; (b) there should be at least one autocatalytic step or, alternatively, cross-catalysis between two steps of the reaction mechanism; and (c) the system should possess at least two steady states under the initial conditions.…”

“…A detailed description of these and related aspects including limit cycles, bifurcation point, monostability, bistability, Fourier power spectra and Lyapounov exponents is beyond the scope of this review; interested readers are referred to pertinent books [3][4][5] and papers. 7,8 The first paper that considered the use of regular chemical oscillations for analytical monitoring was published by Tikhonova et al 13 in 1978. Since then, little additional research into the analytical potential of oscillating chemical reactions has been carried out.…”

Application of Oscillating Reaction-based Determinations to the Analysis of Real Samples

“…[11][12][13][14][15] From available knowledge on these reactions, it follows that the system must be far from thermodynamic equilibrium (i.e., for DG must be large and negative), which entails using a well stirred continuous-flow reactor (CSTR), [16][17][18] and that one or more autocatalytic or cross-catalytic steps must take place between two steps of the reaction mechanism. 19 Although some oscillating reactions have been used for analytical purposes, particularly the Ce IV -catalysed reaction between malonic acid and KBrO 3 (BZ reaction), 20,21 analytical determinations based on a closed system including the analyte involve labour-intensive procedures that entail re-starting the oscillating system before each new determination. This accounts for the little interest aroused so far by this type of reaction for analytical purposes.…”