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An investigation to see the difference in the rate of reaction when catalyse is added to hydrogen peroxide at different concentrations.

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Tuesday 3rd March William Bowles. Biology plan- an investigation to see the difference in the rate of reaction When catalyse is added to hydrogen peroxide at different Concentrations. I am doing an investigation to look at the difference in the rate of breakdown when catalase is added to hydrogen peroxide when the hydrogen peroxide is of different concentrations. When catalase is added to the hydrogen peroxide then a breakdown takes place and water and oxygen are produced. When I say concentrations I mean with a different ratio of hydrogen peroxide to distilled water. I am doing this investigation to find out how the rate of oxygen produced will differ. The reason why these two substances do react is because enzymes are large proteins that speed up chemical reactions. Catalase is an enzyme that is specific for the breakdown of hydrogen peroxide to water and oxygen. So when catalase is added the breakdown starts immediately. The following information is quoted from Encarta: In their globular structure, one or more polypeptide chains twist and fold, bringing together a small number of amino acids to form the active site, which is where the reaction takes place. Enzyme and substrate fail to bind if their shapes do not match exactly. This ensures that the enzyme does not participate in the wrong reaction. The enzyme itself is unaffected by the reaction. When the products have been released, the enzyme is ready to bind with a new substrate. So catalase couldn't react with anything other than hydrogen peroxide because the two of them wouldn't fit together. Yeast contains catalase, all the cells contain catalase because it is needed to get rid of the H2O2 which is made during the chemical reactions that release energy in respiration. The part in purple is the hydrogen peroxide and the part in blue is the catalyse. You can see that when they lock together the breakdown takes place and oxygen and water is formed. ...read more.


E.g. if your apparatus isn't airtight then some oxygen that is produced will escape and this will affect your results. I can control this factor by checking everything over at the beginning. The measurements I will make are the volume (in cm3) of oxygen collected in the measuring cylinder. Tube Volume of H2O2 (CM3) Volume of water (CM3) conc. 1 1.0 0 10 vol. 2 0.8 0.2 8 vol. 3 0.6 0.4 6 vol. 4 0.4 0.6 4 vol. 5 0.2 0.8 2 vol. 6 0 1.0 0 vol. The values are suitable and will make my results more reliable because as I found out in my preliminary work if you have a large volume of liquid in the test tube then the rate of oxygen produced is too quick to get any good results from. The measuring cylinder gets filled in under 5 seconds. They are also good because they are all easy to deal with. It isn't complicated to work them out because it works in a pattern. My measurements won't be extremely accurate because if you are sucking a liquid up with a syringe then you won't be able to get exactly the measurement you want because it is very difficult. My observations won't be amazingly accurate either because it is hard to see the exact level of the water when the reaction is taking place because sometimes the level is falling rapidly. But I will make my results as accurate as I can with these limitations, by using an accurate stop watch and measuring oxygen given off to nearest 0.5cm3. Preliminary work I had to do quite a lot of preliminary work to gather evidence to support my investigation. Also, to ensure my investigation is done in the easiest and most efficient way possible. In my preliminary work I found that you should always stir the catalase because if you don't the reaction is slower because some of the yeast cells settle to the bottom. ...read more.


Other than that I can't recall anything that would have made my investigation unfair. To make my results more reliable I could have done the test even more times to gain a larger average and also get better and better at doing the investigation fairly. That way you could seek out more anomalous results and gain more accurate results. To extend the investigation I could do it with different people and maybe compare my results to other peoples. I could try different batches of yeast to see if it really did make a difference. To improve my method I could use much more sophisticated equipment. Such as: a way to carry out the investigation where you can keep a constant temperature. E.g. A room that is temperature controlled. Computer equipment that records the volume of oxygen produced when it s exactly the required time. Advanced equipment that would ensure I put every last drop in when I am doing the investigation. For accuracy I tried to be as accurate as possible, however there were some things I didn't control. The results might not have been as accurate as they could have been when timing. I only used a stop clock, which relied on my reaction, to stop the clock. Everyone's reaction times are different so is not particularly the most accurate way of timing. Also you had to decide where you would start timing, when you first tart pushing the syringe or when you have finished. All these things make difference but I think I got past the problem because I ensured that I did the same for each one. If I were to do this experiment again I would take into account all the problems I have noticed here. I will also try to be more accurate. However despite these criticisms I do feel that my conclusion is reliable, as I only had two anomalous results, and it does support my prediction. - 1 - ...read more.

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