BelousovZhabotinskyReaktionssystemen

The Belousov–Zhabotinsky reaction, often abbreviated as the BZ reaction, is a class of oscillating chemical reactions that produce periodic changes in color and composition in a closed solution. It is a classic example of non-equilibrium thermodynamics and chemical self-organization, demonstrating sustained temporal oscillations rather than a simple creeping toward equilibrium.

History and discovery: The reaction was first observed by Boris Belousov in the 1950s, who reported cyclical behavior in a reaction mixture that appeared to be straightforward. His findings were initially met with skepticism. Anatol Zhabotinsky later conducted influential experiments in the 1960s that confirmed the oscillatory behavior and helped bring wider attention to the phenomenon, turning it into a foundational example in the study of dynamic chemical systems.

Mechanism and typical composition: A standard BZ reaction uses an acidic aqueous solution containing malonic acid, an oxidizing agent such as potassium bromate, and a metal ion catalyst or colorimetric indicator such as ferroin or cerium(IV). The system undergoes a network of coupled redox reactions that create feedback loops, leading to regular cycles of oxidation and reduction. The color of the solution often shifts in a periodic manner, reflecting changes in the oxidation state of the catalyst or indicator. A simplified mathematical description of the essential kinetics is given by the Oregonator model, developed by Field, Körös, and Noyes in 1972.

Significance: The Belousov–Zhabotinsky reaction is a foundational example in the study of nonlinear chemical dynamics, pattern formation, and reaction-diffusion systems. It has inspired extensive research into chemical waves, temporal oscillations, and spatiotemporal patterns observed in gels and thin films.