Oscillating Reactions: The Briggs-Rauscher
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by Super User, 8 years ago
NOTE: The yellow color of solution A was solved almost instantly by Bill Smathers. The iodate was likely contaminated with iodide. In acid, the lead to the production of I2, which gave the solution a yellow color. Upon addition of B, the I2 was sequestered by malonic acid!
The Briggs-Rauscher oscillating reaction is one of the very few oscillating reactions that we know of.
Throughout the reaction, the concentration of iodide (I-) goes up and down, and this causes a swap between 2 processes. The the concentration is high, the process that consumes iodide is favored. When it is low, the process that produces it is favored. This causes a constant fluctuation of iodide.
As the iodide increases, it forms I2 which is yellow, then the I2 eventually combines with I- to form I3. This complexes with starch and forms a blue-black complex. The iodide producing process is then shutdown and the process that consumes it takes over. The iodide concentration drops, the I3-starch complex falls apart and the color dissipates. The I2 is sequestered by malonic acid and the solution reverts to colorless.
The [i-] continues to fall until the other process then takes over. Iodide is produced again and the cycle repeats itself.
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The Briggs-Rauscher oscillating reaction is one of the very few oscillating reactions that we know of.
Throughout the reaction, the concentration of iodide (I-) goes up and down, and this causes a swap between 2 processes. The the concentration is high, the process that consumes iodide is favored. When it is low, the process that produces it is favored. This causes a constant fluctuation of iodide.
As the iodide increases, it forms I2 which is yellow, then the I2 eventually combines with I- to form I3. This complexes with starch and forms a blue-black complex. The iodide producing process is then shutdown and the process that consumes it takes over. The iodide concentration drops, the I3-starch complex falls apart and the color dissipates. The I2 is sequestered by malonic acid and the solution reverts to colorless.
The [i-] continues to fall until the other process then takes over. Iodide is produced again and the cycle repeats itself.
------------------------------------------
Nile Red Shop: https://www.nilered.ca
Patreon: https://goo.gl/3h353G
Facebook: https://goo.gl/uyxvJV
Twitter: https://goo.gl/uCmnV4
Personal Instagram: https://goo.gl/EdBq4b
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Super User uploaded a new media, Oscillating Reactions: The Briggs-Rauscher
8 years ago
