The Briggs-Rauscher Reaction as a Model of a Chemical Clock

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Formal Metadata

Title
The Briggs-Rauscher Reaction as a Model of a Chemical Clock
Alternative Title
Die Briggs-Rauscher-Reaktion als Modell einer chemischen Uhr
Author
Hock, Bertold
Bolze, Alfred
Contributors
Trude Hard (Redaktion)
Horst Wittmann (Kamera und Schnitt)
License
CC Attribution - NonCommercial - NoDerivatives 3.0 Germany:
You are free to use, copy, distribute and transmit the work or content in unchanged form for any legal and non-commercial purpose as long as the work is attributed to the author in the manner specified by the author or licensor.
DOI
IWF Signature
C 1495
Publisher
IWF (Göttingen)
Release Date
1983
Language
English
Producer
IWF
Production Year
1980

Technical Metadata

IWF Technical Data
Film, 16 mm, LT, 45 m ; F, 4 min

Content Metadata

Subject Area
Abstract
Chemical oscillation reactions are made visible by the periodic appearance and disappearance of an iodine-starch complex. The oscillation is based on autocatalytic reactions, in which intermediary compounds are oxidized and reduced in rhythmic sequence. The total reaction is driven by the decarboxylation of malonic acid. With time-lapse.
Keywords
Briggs-Rauscher reaction
chemical clock
model reaction
oscillation reaction
synergetics
cell biology
Computer animation
Computer animation
To initiate a Briggs-Rauscher reaction, first make up three solutions. Solution A contains hydrogen peroxide. B is a solution of potassium iodate and perchlorid acid. Solution C contains malonic acid, manganes sulphate and soluble starch.
As soon as the reactants mix, the chemical reaction begins. The colourless solution turns golden brown; then it changes to deep blue - and indication of the formation of a starch -iodine complex. In the further course of the reaction, the blue colour disappears, the solution becomes colourless, and the cycle is repeated again. During the reaction, individual reactants are used up; bubbles of gas are produced: CO 2 is released. The concentrations of the reactants change periodically.
When the experiment is repeated speeded up eight times, the oscillations are more clearly apparent.
Towards the end, the reaction velocity decreases. Finally, the solution remains blue.
The third experiment at doubled speed. The oscillations are due to autocatalytic reactions. The intermediate compounds produced periodically change their state of oxidation. Iodine is alternately produced and used up. The periodical occurrence of a substance - for example, the liberation of iodine - determines the time pulse of the oscillation. This forms base of our chemical clock.
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AV-Portal 3.9.1 (0da88e96ae8dbbf323d1005dc12c7aa41dfc5a31)