Academic Chemistry
Class Notes
9/2/2015
Catalytic Decomposition of Hydrogen Peroxide Demonstration
This demonstration evolves a lot of heat as shown by the steam coming off
the foam as it is produced. The reaction, therefore, is exothermic.
The action of a catalyst is demonstrated. The catalyst is the I- (aq) ion that
speeds up the decomposition of the hydrogen peroxide.
The decomposition of hydrogen peroxide produces steam and oxygen gas.
The oxygen gas and water vapor cause the dishwashing liquid to foam.
Chemical Equation
KI
H2O2(aq)  H2O(l) + O2(g) + ∆
Thermite Reaction
The Hindenburg video we viewed in class discussed the thermite
reaction. The following chemical equation describes the thermite
reaction:
Fe2O3(s) + Al(s)  Al2O3(s) + Fe(l) + ∆
The reaction has been used in welding, the preparation of metals from their
oxides, and the production of incendiary devices. The process is initiated by
heat but then becomes self-sustaining. The reaction can proceed in the
absence of oxygen since it provides its own oxygen.
The large amount of energy released by the reaction is sufficient to raise the
temperature of the products above the melting point of iron producing
molten iron. Underwater welding is possible since the iron can remain red
hot under water.
Source: Shakhashiri, B.Z. Chemical Demonstrations: A Handbook for
Teachers of Chemistry