This Demonstration shows the catalytic decomposition of hydrogen peroxide.
100mL of 30% hydrogen peroxide is pour into a flask that is wrapped in aluminum foil. A small packet of 2 grams of manganesse dioxide MnO2 is wedged between the rubber stopper and the rim of the glass. When opened the packet releases and the reaction starts.
*****Important Note- There must be hole in the rubber stopper (use a 1 hole or two holed rubber stopper) incase the MnO2 reacts prematurely with the H2O2. It is not a sealed container and will not explode.