Belousov-Zhabotinskii mixture

Another form of behaviour exhibited by a number of chemical reactions, including the Belousov-Zhabotinskii system, is that of excitability. This concerns a mixture which is prepared under conditions outside the oscillatory range. The system sits at the stationary state, which is stable. Infinitesimal perturbations decay back to the stationary state, perhaps in- a damped oscillatory manner. The effect of finite, but possibly still quite small, perturbations can, however, be markedly different. The system ultimately returns to the same state, but only after a large excursion, resembling a single oscillatory pulse. Excitable B-Z systems are well known for this propensity for supporting spiral waves (see chapter 1). 

We have investigated the transitions among the types of oscillations which occur with the Belousov-Zhabotinskii reaction in a CSTR. There is a sequence of well-defined, reproducible oscillatory states with variations of the residence time [5]. Similar transitions can also occur with variation of some other parameter such as temperature or feed concentration. Most of the oscillations are periodic but chaotic behavior has been observed in three reproducible bands. The chaos is an irregular mixture of the periodic oscillations which bound it e.g., between periodic two peak oscillations and periodic three peak oscillations, chaotic behavior can occur which is an irregular mixture of two and three peaks. More recently Roux, Turner et. al. 

B-Z reaction (Belousov-Zhabotinskii reaction) A chemical reaction that shows a periodic colour change between magenta and blue with a period of about one minute, it occurs with a mixture of sulphuric acid, potassium bromatefV), cerium sulphate, and... 

Belousov-Zhabotinskii reaction (B-Z reaction) An oscillating chemical reaction in which there are periodic oscillations in the color of a mixture of sulfuric acid, potassium bromate, cerium (or iron) sulfate, and propanedioic acid. The period of oscillation is about one minute. The color changes are caused by repeated oxidations and reductions of cerium (or iron) ions. The reaction was first observed by the Russian chemist B. P. Belousov in the case of cerium and modified to iron by A. M. Zhabotinskii in 1963. The mechanism of the B-Z reaction is highly complicated and involves a large number of individual steps. 

---