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DECOMPOSITON OF HYDROGEN PEROXIDE WITH HEAVY METAL CATALYSTS Aim: Various metal oxides will be added to the hydrogen peroxide and the production of oxygen of the reaction mixture will determine catalysis. The volume of oxygen evolved will be observed and recorded to measure the reaction rate and the reaction rates of the different metal oxides will be compared. Scientific Background: Catalysis is the process by which the activation energy is lowered to allow the reaction to occur at less extreme conditions, during the process the catalyst does not under go any overall change. The catalyst reduces the activation energy by using a chemical route with activation energy less then the route, which would otherwise be taken in the absence of the catalyst. During catalysis the reacting substance usually undergoes a change or changes in oxidation state, therefore the catalyst must also be able to change its oxidation state. The s & p block metals possess or exhibit only one oxidation state. The reason being that their oxidation state depends on the removal of electrons from their outermost shell. The further removal of electrons will result in the penetration of stable inner shells that are filled with electrons. This would require an excessive amount of energy. As a result of this, the catalysts are not able to enter their different oxidation states and this therefore does not allow them to successfully act like a catalyst. Transition metals can form ions, which have D orbitals, which are partially filled with electrons. D orbitals are the outer most shells and they can hold up to 10 electrons and they also have similar energy levels, which allows them to overlap within each other. It is this process which allows the transition metals to have various oxidation states. The orbital possess the same energy, which enables transition metal ions to enter their different oxidation states. This therefore allows them to act as catalysts. ...read more.


40 7 6.5 6.5 6.7 50 7.5 7 6.5 7.0 60 7.5 7 6.5 7.0 70 7.5 7 6.5 7.0 80 7.5 7 6.5 7.0 90 7.5 7 6.5 7.0 100 7.5 7 6.5 7.0 110 7.5 7 6.5 7.0 120 7.5 7 6.5 7.0 130 7.5 7 6.5 7.0 140 7.5 7 6.5 7.0 150 7.5 7 6.5 7.0 160 7.5 7 6.5 7.0 170 7.5 7 6.5 7.0 180 7.5 7 6.5 7.0 190 7.5 7 6.5 7.0 200 7.5 7 6.5 7.0 On the next page is a graph with a line of best fit representing the results in the last column above, which represents the average results. The following table shows the amount of oxygen evolved in a certain amount of time by the catalyst Al2O3. Time from start of exp. (s) Volume of oxygen produced by Al2O3 (cm3) Reading 1 Reading 2 Reading 3 Average 10 3 2 3 2.7 20 3 2 3 2.7 30 3 2.5 3.5 3.0 40 3.5 4 3.5 3.7 50 3.5 4 3.5 3.7 60 3.5 4.5 4 3.8 70 4 4.5 4 4.2 80 4 4.5 4 4.2 90 4 5 4 4.3 100 4 5 4 4.3 110 4.5 5.5 4 4.7 120 4.5 5.5 4.5 4.8 130 4.5 5.5 4.5 4.8 140 5 5.5 4.5 5.0 150 5 5.5 4.5 5.0 160 5 5.5 5 5.2 170 5 5.5 5 5.2 180 5 5.5 5 5.2 190 5 5.5 5 5.2 200 5 5.5 5 5.2 On the following page the graph for the results above has been included. Only the average results are shown. The following table shows how much gas is evolved from the catalyst Copper Oxide (CuO): Time from start of exp. (s) Volume of oxygen produced by CuO (cm3) Reading 1 Reading 2 Reading 3 Average 10 2 3 2 2.3 20 3 4 3 3.3 30 4 5 4 4.3 40 5 6 5 5.3 50 5.5 7 5.5 6.0 60 6 7.5 5.5 6.3 ...read more.


The apparatus allowed precise results to be collected. Evidence for this is that the difference between repeated readings is small and the amount of anomalous results is small thus the number of errors must be small. The plan and method that was used for this experiment can be said to be very good. The reason being that both fulfilled their intended tasks. Before the investigation, it was desired to find how different metal catalysts affect the rate of reaction and to draw conclusions, which did or did not cohere to the prediction made. This was achieved as it could be seen whether transition metal catalysts and metal catalysts had an affect on the rate of reaction. As in any investigation, errors were present despite the fact that prior to the investigation all such errors were minimised. Below the errors and problems encountered are discussed along with the improvements that could be made to avoid these problems: 1. The volume of gas on the syringe could have been misread which would lead to inaccuracy of results. This could be one reason for why some anomalous results would have appeared. This can be avoided by 2. The stopper was not being placed on the conical flask quick enough and so much gas was lost during this time. By the time the stopper was placed onto the conical flask, the reaction was coming to an end. To prevent further loss of gas in future experiments the following could be done: * Another individual could be asked to place the stopper on, however in this process some gas will still be lost. * A divider flask could be used which is a conical flask that is split into two sections. If the catalyst is placed in one section and the solution is another the divider flask will allow the reactants to be separate for long enough so that the stopper can be placed on. Once this has been done, the conical flask can be tipped over slightly to let the reactants mix. ...read more.

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