Analysis of the Iodine Clock Reaction

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Analysis and Interpretation Experiment 1 Aim 1 – How changing the concentration of I- ions affected the rate of reaction. This was the first reaction I conducted and I did this by keeping everything else constant whilst only changing the concentration of the potassium Iodide. At first I was due to keep the concentration of KI at 1M. However I found that the reaction was happening way to fast. As soon as I added the reactants together it would immediately turn dark blue. I then reduced it by a tenth-fold to 0.1M and I found the same problem. The reaction was finishing too quickly. I finally managed to get it to a suitable time by reducing it to 0.01M. The reason for this I concluded, was the collision theory. At the higher molarities of Potassium Iodide there were too many moles and therefore too many collisions were happening. Therefore the product was being made almost instantly. When I reduced the concentration of the reaction this meant there were less particles of iodide in the system so the reaction was happening slower. I also lowered the concentration of Hydrogen Peroxide 0.017M. I repeated each reaction several times and recorded three of the most valid results. The results were; Experiment | Test (s) | Conc. of KI (M) | Initial Rate (moldm-3) | | 1 | 2 | 3 | Mean | | | 1 | 78.4 | 75.1 | 77.6 | 77.0 | 0.01 | 0.01298139 | 2 | 104.3 | 108.0 | 104.1 | 105.5 | 0.008 | 9.481669x10-3 | 3 | 171.6 | 172.1 | 168.9 | 170.9 | 0.006 | 5.851375x10-3 | 4 | 210.4 | 214.3 | 216.7 | 213.8 | 0.004 | 4.677268x10-3 | 5 | 271.3 | 277.1 | 275.4 | 274.6 | 0.002 | 3.641661x10-3 | As can be seen in the results, as the concentration of KI increases so does the time taken for the reaction to be completed. This is because of the collision theory as I mentioned previously. From this the initial rate can be worked out as proportional to 1/t. However this is

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