Effect of Mno2 on the Decomposition of Hydrogen Peroxide

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Chemistry Catalyst Report

Aim
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 experimentStay 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 usedMeasure the volume using a measuring cylinder

Uncontrollable Variable
The temperature of the H2O2 cannot be controlled because the process, which I am trying to speed up through adding catalysts, is an exothermic reaction, meaning that heat is given off in the process. Because it gives off heat, the temperature cannot be controlled and this would affect my results, as there would be more than one dependent variable. I was only allowed H2O2 from the same source, which means no fresh source of H2O2 at a controlled temperature. I could not wait for the H2O2 to decompose to a certain temperature because that would take too long. I could not use the catalysts to help the H2O2 to decompose to that temperature for the experiment to start because it would be difficult to gage when to take out the catalyst and catalysts are unable to be used up.

Equipment
Top pan balance
H2O2 – 300ml
MnO2 –5g
50ml Beakers - 10
Conical flasks - 5
Spatula
Cotton Wool
Measuring cylinder

Diagram

Method
1.Gather the equipment and set it up like in the diagram above. 2.Using a top pan balance, a beaker and a spatula, measure 0.1g, 0.2g, 0.3g, 0.4g and 0.5g of MnO2 and place them in different beakers. 3.Measure 50ml of H2O2 using a measuring cylinder and fill 5 beakers with 50ml of H2O2 each. 4.Place a new conical flask and enough cotton wool to cover the hole of the conical flask on the top pan balance. Hit the “TARE” button. 5.Pour in 50ml of H2O2

6.Record the mass shown
7.Pour in 0.1g of MnO2 and cover the hole of the conical flask with the cotton wool 8.The total weight of the solution would then be the mass recorded in step 5 plus the mass of the MnO2 in step 7 9.Start timing when the MnO2 is added.

10.Record the mass shown on the top pan balance every 5 seconds. This experiment is to run for only a minute. 11.form a results table
12.Repeat steps 4 to 10 with the different masses of MnO2 and with new cotton wool

 Mass of MnO2(g)0.10.20.30.40.5
Time(s)     
      
050.9551.0250.6648.7248.16
550.9451.0150.6548.748.15
1050.945150.6248.6848.12
1550.945150.6348.6748.09
2050.9450.9950.5748.6548.06
2550.9350.9950.6148.6348.04
3050.9350.9850.6148.6148.00
3550.9350.9850.648.5847.97
4050.9350.9750.5948.5547.92
4550.9250.9650.5848.5247.89
5050.9250.9550.5748.4947.84
5550.9250.9450.5648.4647.78
60  50.9250.9350.5548.4347.72

Evaluation

Catalysts are substances, which help speed up chemical reactions. Reactions happen when the two reacting particles collide, but if the force of their collision is not above a certain level, the reaction would not happen. This minimum amount of energy required for the reaction to take place between the particles is called activation energy. Catalysts are useful because they provide an alternative surface for the particles to react, with a lower activation energy. The disadvantage of using a catalyst is that the reactions are not as energetic and thus the product is less. For this reaction, less oxygen would be produced. 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...
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