Two-color chemiluminescent clock reaction

After mixing two liquids, at first, a weak red glow appears, and then the solution foams and emits a blue glow.

Scientific name: Hydrogen peroxide reacts with pyrogallol, formaldehyde and luminol.


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Wear eye protection and lab gloves. This experiment should be performed in a fume hood.

Avoid contact of hydrogen peroxide, sodium hydroxide and pyrogallol with skin. Pyrogallol can be absorbed through the skin.

Avoid inhaling the formaldehyde vapours

Always follow general safety recommendations. Please note that conducting chemistry experiments you must comply with the relevant legal procedures in your country.

Reaction formula

2CH2O + 3H2O2 → CH2(OH)OO(OH)CH2 + 1O2 +2H2O

C8H7N3O2 + 2OH- + O2 → C8H5NO42- + 2 H2O + N2

Step-by-step instruction

WARNING! This experiment is dangerous! You should NOT perform this at home. ONLY carry out this experiment, if you are a trained chemist, and you understand local safety and legal requirements, which are required to perform such experiments

  1. Mix 40 ml of water and 0.8 g of sodium hydroxide in a 250-ml beaker.
  2. Add 5 mg of luminol, 25 g of potassium carbonate and 1 g of pyrogallol into the beaker. Stir to dissolve.
  3. Add 10 ml of about 40% formaldehyde.
  4. Pour the resulting solution into a 1-l beaker.
  5. Add 30 ml of 30% hydrogen peroxide into the mixture. It is better to do this in a dark room.

Scientific background

There are two oxidation reactions in this experiment. The first reaction is known as Trautz-Schorigin reaction. It is the oxidation of formaldehyde by alkaline hydrogen peroxide in the presence of pyrogallol. Singlet molecular oxygen is produced in this reaction, and it converts to triplet oxygen with a weak emission of red light. This reaction is strongly exothermic, and the solution temperature may increase to 90 °C.

The second reaction is the oxidation of luminol, in which blue glow is emitted. Full detailed reactions are very complicated, and there are only simplified reactions in this description.


Published on 13 April 2015

  • Fire
  • Heating with fire
  • Explosion
  • Poisoned gas
  • Organic
  • Electricity
  • Solution
  • Oxidation reduction
  • Color change
  • Precipitate
  • Gassing
  • Catalyst