Observations on Manganese Dioxide As a Catalyst in the Decomposition of Hydrogen Peroxide: A Safer Demonstration

Concerns have surfaced regarding the safety of several online demonstrations on the decomposition of H2O2. In the demonstrations, a H2O2 decomposition reaction happens rapidly followed by a plume of condensed water vapor shooting out of the flask. A modified protocol with improved safety considerations is described for the decomposition of H2O2 demonstration. In these demonstrations, 44 mu m and 10 mu m size particles of MnO2 are compared in catalyzing the decomposition of 30% H2O2 in a 1 L plastic bottle. The use of 44 mu m particle size MnO2 slowed the reaction significantly relative to 10 mu m particle size MnO2. The experimental procedure developed using 44 mu m particle size MnO2 is reliable and has been tested dozens of times over the past ten years. Critical parameters were identified to ensure the success of the demonstration without compromising the safety of the demonstrator and the audience. This demonstration can easily be conducted in a large well-ventilated classroom and affords an excellent presentation for teaching students about rates of chemical reactions and several topics related to catalysis.