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The aim of this investigation is to find out what affects the rate of reaction when a hydrogen peroxide solution is combined with yeast, potato, carrot or celery.

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Enzyme Coursework Aim The aim of this investigation is to find out what affects the rate of reaction when a hydrogen peroxide solution is combined with yeast, potato, carrot or celery. There are a number of potential variables available; I could change temperature, pH level, amount of yeast, potato, carrot or celery, type of yeast, potato, carrot or celery or concentration of hydrogen peroxide. After discussing with my group, we decided to use the concentration of hydrogen peroxide as the variable for our experiment. We decided against varying the temperature because we would need to get both the yeast and the hydrogen peroxide to an initial temperature, which would be difficult. To vary the pH level would also be difficult and would take a lot of time to get the right pH each time, so this was also decided against. Varying the type of yeast, potato, carrot or celery would not be possible, as only one type of yeast is available to us. Varying amount of yeast added to the hydrogen peroxide would be possible, but my group and I found that it would take up less time and be more straightforward if we were to vary the hydrogen peroxide concentration. ...read more.


I shall also wash my hands thoroughly if I happen to spill hydrogen peroxide on them and after each experiment in case I have spilt hydrogen peroxide on them. Results Concentration of hydrogen peroxide (%) Time (minutes) First experiment (oxygen given off cm�) Second experiment (oxygen given off cm�) Third experiment (oxygen given off cm�) Average (oxygen given off cm�) 100 1 18.7 17.5 18.2 18.1 2 23.5 22.4 25.5 23.8 3 25.3 24.0 29.2 26.2 75 1 12.4 10.1 11.3 11.3 2 15.5 13.2 14.7 14.5 3 17.6 15.8 17.6 17.0 50 1 5.5 6.5 5.7 5.9 2 7.0 7.7 7.1 7.3 3 8.1 9.0 8.5 8.5 25 1 2.5 2.6 2.3 2.5 2 3.7 3.7 3.6 3.7 3 4.8 4.8 4.9 4.8 10 1 1.0 0.5 1.1 0.9 2 1.5 1.2 1.3 1.3 3 2.0 2.2 2.4 2.2 Graph Conclusion From my preliminary work I found out that yeast gives off more oxygen than potato, carrot or celery when reacted with a 100% concentration of hydrogen peroxide solution. From the main experiment, however, I found out that my prediction was correct. I saw that the reaction for all the concentrations began more vigorously than when it was coming towards the end of the three minutes, as all the reactions slow down. ...read more.


There were no anomalous results in my group's experiment, proving that it was carried out accurately. However, if there were any results that I found to be inaccurate or anomalous, I would simply discard those results from my results table, and perform that particular experiment again. I think that the evidence that I have gained from this investigation is reliable as there were no anomalous results included and all of the experiments were carried out carefully and accurately. The evidence that I have gained helped me come to a firm conclusion that a high concentration of hydrogen peroxide gives off more oxygen than a low concentration. The graph clearly shows this trend of that the higher the concentration of hydrogen peroxide, the more oxygen is given off. To clarify this pattern further, I would need to carry out more experiments for different hydrogen peroxide concentrations. For example, I may need to carry out experiments for concentrations of 5%, 15%, 35%, 60% and 85% in addition to the concentrations I used in the investigation (10%, 25%, 50%, 75% and 100%). For the experiment, I could have carried out an experiment for a 0% concentration of hydrogen peroxide, but as there would be no hydrogen peroxide to react with the yeast, there would be no reaction, and therefore no oxygen given off. Jordan Hoose 1 ...read more.

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