B12 Oscillating Reaction with Potentiometric Data

Description
The classic Belousov-Zhabotinsky reaction, which is a cerium catalyzed oxidation of malonic acid by bromate ions, is run in the presence of the redox indicator, ferroin. The mixture changes from green to blue to violet and finally red at 1 to 2 minute intervals. As the yellow cerium(IV) concentration increases, the redox potential increases, and blue Fe(II) ferroin is oxidized to the red Fe(III) form. Note bubbles of CO₂ product accumulating on the electrode. A cyclic potential change of 200 mv is recorded with a platinum electrode. Since the reaction is very complex, the reference may be checked for additional equations and information.

Equation
2 BrO₃^- + 12 H⁺ + 10 Ce³⁺--> Br₂ + 6 H₂O + 10 Ce⁴⁺(yellow)

Br₂ + malonic acid --> BrCH(CO₂H)₂ + Br^- + H⁺

BrCH(CO₂H)₂ + 4 Ce⁴⁺ + 2 H₂O --> HCO₂H + 2 CO₂ + Br^- + 5H⁺ + 4 Ce³⁺

Reference
B. Z. Shakhashiri, "Chemical Demonstrations", Vol. 2, The University of Wisconsin Press, Madison ,Wisconsin, (1985) pp.240,257.