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biological nitrification,

This is an eye-catching demonstration producing large quantities of condensed water vapor which will shoot out of the flask up to the ceiling. Initially after addition of the manganese dioxide, you will see a small amount of condensed water vapor start to form inside the flask. After about a minute the intensity of the formation increases and the flask heats up until finally a cloud of condensed water vapor shoots out of the flask 20 to 30 feet toward the ceiling. During the demonstration, the reaction is so exothermic that the bottle shrinks in size. You should keep an empty 2L bottle on the side so that your audience can compare the two flasks after the reaction. Here is what happens: MnO2 catalyzes the breakdown of the H2O2 to H2O and O2 gas. As the bottle heats up in this exothermic reaction, the water condenses out as vapor, and the oxygen gas generated in the reaction forces it out of the bottle creating the cloud of condensed water vapor. This is a great demonstration to illustrate the effect of the breakdown of H2O2 to H2O and O2: Manganese dioxide catalyzes the decomposition of hydrogen peroxide to oxygen and water. Since manganese dioxide is a catalyst, it is not consumed in the reaction. Normally the activation energy for this uncatalyzed reaction is around 75 KJ/mole (Moelwyn-Hughes). With the addition of the synthesized catalyst, MnO2, we can actually lower this activation energy down to about 58 KJ/mole (Moelwyn-Hughes) and that speeds up the decomposition by 1073 times at 200C. The calculations using the Arrhenius equation: k = A e – [Ea/RT] where Ea = activation energy in Joules/mole, R = universal gas constant 8.3145 Joules/K-mole T = absolute temperature in Kelvin (K) and A = collision frequency factor k = A e -58,000/8.3145 x 293 catalyzed k = A e -75,000/8.3145 x 293 uncatalyzed k 17,000/8.3145 x 293 catalyzed / k uncatalyzed = e = 1073 The rate constant of the catalyzed v. uncatalyzed has increased by 1,073 times. Therefore, the rate of catalyzed is 1073 times the rate of the uncatalyzed.