Effect of Mno2 on the Decomposition of Hydrogen Peroxide Essay Example

Catalysts are never used up. And because they are never used up, we are able to collect them back after the reaction, still as good as before without changing chemically.

Before adding the catalysts, only some particles have enough energy to react. It is represented by the green section. The rest of the particles that cannot pass the activation energy barrier is represented by the blue. 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.

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 heat. Because there is no way I could do all the experiment at the same time, the temperature of the

hydrogen peroxide changes every time I start the experiment. I have explained this more clearly in the section of uncontrollable variables.

Next, the beakers that the hydrogen peroxide was stored in were not washed clean and not washed by the lab technicians.This meant that the beakers were washed by the previous batch of students who used them and they might not have washed them properly. Because the students are also not provided with chemicals to wash the beaker such that it is clean of impurities, some of the beakers used may have been contaminated. When I was pouring the hydrogen peroxide into the conical flask using a funnel, because of liquid having a tension property, some of the hydrogen peroxide “stuck” on to the funnel. This meant that not all of the 50ml of hydrogen peroxide was poured in.

?Because it would be hard to measure 0. g of MnO2 in a conical flask, I measured it in a beaker. By putting it in a beaker, when I tried to pour it into the conical flask, some of the powder got stuck onto the beaker, due to static electricity.

Ways to improve

Have the lab technician clean the equipment with proper cleaning methods first, preventing contamination. Use freshly made hydrogen peroxide and use it for the experiment straight away or use the hydrogen peroxide for the experiment after a timed period of maybe 5 minutes, this way all the hydrogen peroxide used from the fresh source is always decomposed to that same level.

Use a conical flask with a larger neck or use a big beaker, this way I would not have had to use a beaker because the reaction

is not very violent, the liquid from the spewing bubbles would not burst out of the beaker if it was big enough. Because the masses of MnO2 was small, I could have measured the mass of the MnO2 on another spatula. If the MnO2 still stuck to the spatula due to static electricity, even less MnO2 would be stuck to the spatula because the surface area of which the MnO2 is exposed to is smaller.