Effect of Mno2 on the Decomposition of Hydrogen Peroxide

1436 Words Sep 19th, 2008 6 Pages
Chemistry Catalyst Report

I am trying to investigate the effect of the mass of magnesium dioxide used on the speed of the reaction of 2H2O2(aq)  2H2O(l) + O2(g). I hypothesize that the speed of the reaction is proportional to the rate of decomposition.

Independent Variable
The mass of MnO2 used

Dependent Variable
The rate of decomposition through the amount of mass lost

Controlled Variables
Environment of the experiment Stay in the same place to carry out the experiment and finish the experiment as fast as possible in case of a sudden change in some areas of the environment
Volume of H2O2 used Measure the volume using a measuring cylinder

Uncontrollable Variable
The temperature of the H2O2 cannot be controlled because the
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After adding the catalysts, the catalysts provide an alternative path for the particles to react. The average activation energy is lowered and now, more particles are able to react. This graph shows the before and after effect of adding a catalyst on the activation energy required for the reaction to start.

Through the results obtained, it is clear that the mass of catalyst used is proportional to the speed of the reaction. The higher the mass of catalyst used, the more particles of catalyst is in the solution, the more alternative paths of reacting is given to the particles, therefore the faster the reaction. It can thus be concluded theoretically and practically that the more mass of catalyst used, the faster the reaction rate.

Mass of catalyst(g) 0.1 0.2 0.3 0.4 0.5
Gradient of the graph -0.00498 -0.00519 -0.00184 -0.00476 -0.00838

I have graphed the results from the experiment. The above table shows the gradients I had derived from the graphs. All the results fit my hypothesis except for 0.3g and 0.4g. From the graph, it can be derived that even though the rate of reaction is proportional to the catalyst, it is not directly proportional.
Sources of Error

 Results from obtained from this lab experiment can never be accurate because of a few reasons. Firstly, catalysts and reaction are sped up by heat. The decomposition of hydrogen peroxide to water and oxygen is an exothermic reaction. This means that the decomposition reaction gives off