Oxidation-reduction reactions {Belousov-Zhabotinskii reaction} {Belosov-Zhabotinski reaction} (B-Z reaction) (BZ reaction) using sodium bromate, malonic acid, sulfuric acid, and cerium ions, and involving twenty-one reaction steps, can produce spatial patterns in dishes, after delays.
As shown by ferroin indicator, cerium-ion catalysts change oxidation state, blue and magenta, or do not change oxidation state, yellow and clear, to make concentric circles or spirals. Concentrations oscillate with period {limit cycle, concentration}.
feedback
Oscillation happens only far from chemical equilibrium and requires feedback.
diffusion
Spatial patterns require diffusion.
chemical patterns
Non-linear multiple-reaction kinetics and feedback, through diffusion or direct chemical addition, can form temporal and spatial patterns far from equilibrium. Patterns require flows and feedback. Reaction far from equilibrium between high-concentration species typically affects low-concentration catalytic compound, which can have two different oxidation states or shift easily between acid and base. Reaction rates oscillate.
Chemical-pattern formation depends on dissipative structure theory. Turing [1952: The Chemical Basis of Morphogenesis] invented chemical and biological spatial-pattern-formation theory. Belousov and Zhabotinskii [1958, 1964] discovered oscillating chemical reaction, and Noyes [1972] analyzed mechanism {oregonator model}.
Continuous-flow stirred-tank reactor (CSTR) studies oscillating systems over time. Continuous-flow unstirred reactor (CFUR) studies oscillating systems over space.
Physical Sciences>Chemistry>Organic>Chemical Reaction
5-Chemistry-Organic-Chemical Reaction
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Date Modified: 2022.0224