Briggs-Rauscher reaction - 'The Oscillating Clock'

The Briggs-Rauscher reaction, also known as 'the oscillating clock', is one of the most common demonstrations of a chemical oscillator reaction. The reaction begins when three colorless solutions are mixed together. The color of the resulting mixture will oscillate between clear, amber, and deep blue for about 3-5 minutes. The solution ends up as a blue-black mixture.


Solution A:
Add 43 g potassium iodate (KIO3) to ~800 mL distilled water. Stir in 4.5 mL sulfuric acid (H2SO4). Continue stirring until the potassium iodate is dissolved. Dilute to 1 L.

Solution B:
Add 15.6 g malonic acid (HOOCCH2COOH) and 3.4 g manganese sulfate monohydrate (MnSO4 . H2O) to ~800 mL distilled water. Add 4 g of vitex starch. Stir until dissolved. Dilute to 1 L.

Solution C:
Dilute 400 mL of 30% hydrogen peroxide (H2O2) to 1 L.


1. Pour 300 mL each of solutions A and B into a large beaker.
2. Turn on the stirring plate. Adjust the speed to produce a large vortex.
3. Add 300 mL of solution C into the beaker. Be sure to add solution C after mixing solutions A + B or else the demonstration will not work. Enjoy!


Wear safety goggles and gloves and perform the demonstration in a well-ventilated room, preferably under a ventilation hood. Use care when preparing the solutions, as the chemicals include strong irritants and oxidizing agents.