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Home Dissipative Structures Briggs-Rauscher Reaction

Briggs-Rauscher Reaction

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The Briggs-Rauscher Reaction is an oscillating chemical reaction.  It is driven by the oxidation of malonic acid to iodine-malate. Free iodine is visualized by starch (blue-black iodine-starch complex).

Approx. sum reaction (very, very simplified):
IO3− + 2H2O2 + CH2(COOH)2 + H+ → ICH(COOH)2 + 2O2 + 3H2O

Here is a working procedure to make the reaction:

NO WARRENTY, DO ALL THE REACTIONS AT YOUR OWN RISK AND WITH EXPERIENCED SUPERVISORS !

Materials

(1) 4 Erlenmeyer flasks

(2) magnetic stirrer

Chemicals

KIO3, H2SO4, malonic acid, manganese sulfate monohydrate (MnSO4 . H2O), hydrogen peroxide (H2O2 ), water (H2O)

Procedure

(1) Prepare to following three solutions in separate flasks:

Warning !!! H2SO4 (conc.) is very caustic ! Never put water in sulfuric acid - it immediately boils ! Always water first, then the acid !

Wear eye protection, gloves  and lab-coats ! Do the reaction only at your own risk.

A: KIO3 (4.3g) + H2O (80ml)

+ H2SO4 (conc., 0.45ml, stirring)

+ H2O (20ml => ad 100ml)

B: malonic acid (1.56 g)

+ Mn(II)SO4*H2O (0.34g)

+ H2O (80ml)

+ Starch (ca. 0.4g)

Warning !!! H2O2 is a strong oxidant - protect your skin it hurts terrible, if it drops onto your skin. Wear eye-protection and gloves !

C: H2O2 (30%, 40ml) + H2O ad 100ml

(2) Mix A + B and stirr for 1 min,

(3) then add C

The YouTube (R) video above shows, how the reaction should look like.


This reaction was used as a demonstration reaction at the FLinT course "Assembling Minimal Living Systems" at the University of Southern Denmark SDU ( Course supervisor: Martin Hanczyc, PhD) .

Experimentator: Mark Doerr, PhD