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
