Chemical demonstration

The serpent

A great demonstration of the action of an inorganic catalyst on the rate of a chemical reaction is the "Serpent".



The ingredients for the serpent demonstration.

To conduct this activity you will need a:

- pneumatic trough

- Potassium iodide crystals

- 33% hydrogen peroxide

- Dishwashing liquid

- Green food dye.

- 100ml measuring cylinder

Place 20ml of hydrogen peroxide solution in the measuring cylinder. Add detergent (about 6 ml) and a few drops of green food dye. Place the measuring cylinder in the trough and add a small spatula full of KI crystals.


The demonstration shows vividly the increase in the rate of the reaction represented by the equation


2H2O2(aq) => 2H2O(g) + O2(g)
Look at the reaction. Is this reaction exothermic or endothermic?
Do the products contain more energy than the reactants?