While hydrogen peroxide is relatively stable at room temperature, numerous substances act as catalysts of their decomposition, among others: transition metals, alkali, and metal oxides. The light of day also favors the decomposition of hydrogen peroxide, so it must be kept in opaque containers.
Hydrogen peroxide decomposition catalyzed by potassium iodide is shown in the following experiment. In addition, a small amount of soap has been added to make the evolution of oxygen more evident. The reaction of imbalance that occurs is:
H2O2 - > H2O + 1/2 O2
The Frost of oxygen diagram shows that hydrogen peroxide is thermodynamically unstable, and that is above the line that connects the species with 0 and - 2 oxidation States (dioxygen, and water) in which decomposes the hydrogen peroxide. This process is known as disproportion.
Frost diagram of the oxygen in acidic solution.
Department of Inorganic Chemistry
Universidad de Alicante Carretera de San Vicente del Raspeig s/n 03690 San Vicente del Raspeig Alicante (Spain)