"Chemical pendulum" experiment
The Belousov-Zhabotinsky reaction
This stunning chemical experiment is a modification of one of the most complex chemical reactions, the Belousov-Zhabotinsky reaction.
Reagents and equipment:
- concentrated sulfuric acid;
- solution of cerium(IV) sulfate (10.6 g in 1 liter);
- solution of malonic acid and potassium bromide (32 g of malonic acid + 7 g of potassium bromide in 1 liter);
- solution of potassium bromate (38 g in 1 liter);
- saturated solution of ferroin;
- magnetic mixer.
Pour the solution of potassium bromate into the beaker, then the solution of malonic acid and potassium bromide, and then add the solution of cerium(IV) sulfate and concentrated sulfuric acid. Then the saturated solution of ferroin.
The Belousov-Zhabotinsky reaction is one of the most popular reactions in science. It has been carried out by scientists in different fields, such as chemistry, physics, mathematics and biology. Numerous doctoral dissertations have been written about it, but the full mechanism has yet to be fully explained. The most detailed mechanism today is a set of 80 elementary reactions.
The solution changes color because different colors overlap, for example the bromine released has a reddish-brown color, and the ferroin solution containing bivalent iron is red, and when it oxidizes to a trivalent state it turns blue. Ce⁺⁴ ions have a yellowish-orange color, while Ce⁺³ ions are colorless. As all of these oxidation-reduction reactions take place in the same vessel, this incredible change of color takes place.
Wear protective gloves and glasses. Observe safety rules when working with concentrated acids.
Warning! Only under professional supervision.