The Briggs-Rauscher reaction is a colourless solution that becomes amber then suddenly turns blue-black. The blue-black will fade to colourless, and the cycle will repeat several times with a period which initially lasts a few seconds but gradually lengthens. After a few minutes the solution will remain blue-black that liberates iodine vapors.
The reaction can occur via two differ processes. A radical process and a non radical process. Which of these two processes dominates is determined by the concentration of iodide ions in the solution. When iodide ion concentration s low the radical process dominates. when its high the non radical process is the dominant. Basically each of the processes of produces conditions favorable to the other, and, therefore, the reaction oscillates between the two.
“How it Begins” Kevin MacLeod (incompetech.com)
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