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For my coursework I had to study enzymes (catalysts) and the rate of reaction of catalase breaking down hydrogen peroxide.

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Introduction

Topic review For my coursework I had to study enzymes (catalysts) and the rate of reaction of catalase breaking down hydrogen peroxide. Enzymes are the catalysts that speed up chemical reactions in living organisms. They are very vital for us as without them we could not live. Essentially they are proteins made up of long chains of amino acids. The chains are different in each protein, so unsurprisingly the shapes are also different and an enzyme's shape is very crucial to how it works. The molecules must fit correctly into a part of the enzymes called the active site, otherwise it will be useless. A visual way of explaining this idea is the lock-and-key model.... The diagram is very simplistic and makes it very easy in order to understand the nature of the enzyme. If it doesn't fit, it won't work. It shows the molecule and the active site before the reaction, and then the initial reaction between the two. Once reacted, the product molecules leave the active site, and the enzyme can then be used again. When the catalysts react they speed up the chemical reaction at an astronomical rate. For any reaction to happen the molecules need to bump into each other. So if the temperature is very low, the molecules move slowly and therefore are very unlikely to collide. This decreases the rate of reaction. However, if the temperature is increased, the molecules have more energy and as a result move faster and collide more frequently with more energy. This is known as the collision theory which as a result, increases the rate of reaction. Just like other organisms it cannot survive murderous heat conditions as it interferes with its key functions. Once the enzyme is introduced to a very high temperature it begins to slowly change its shape. This does not destroy it, but even when the enzyme is cooled down; it still cannot return to its original shape. ...read more.

Middle

It was crucial to cut these pieces the same size because if cut different on one test, the rate of reaction might have been quicker or slower and in turn, ruining the whole experiment. The other variables which I aim to strictly take account for include: * Surface Area of Potato: I will cut the pieces of potato accordingly so they are the same size for each test in order for them to be as close as possible in terms of size and so the same amount of catalase can be exposed to the hydrogen peroxide. * Temperature: I will try to keep the temperature of the reactants equal throughout the experiment by acting the experiment at room temperature. * Mass of Enzyme: I will attempt to keep this the same for each test by cautiously weighing the parts of the potato on precise weight scales. * Concentration of Hydrogen Peroxide: I will keep this the same for each part of my test by gently measuring out the solution in a measuring cylinder. Preliminary data For my preliminary test I decided to use 4 grams of potato as I deemed this to be a suitable amount for the experiment. I poured the H202 with the potatoes and allowed the reaction to last for 2 minutes before taking down the results. I did this 5 times, however I decreased the level of H2O2 by 20% each time, apart from my last test in which I decreased it by 10%. I diluted the solution with water to make it balanced. The experiment was a success; unfortunately the level of oxygen produced by the weight of the potato was very low. It is doubtful that the weight of the enzyme caused the result to be so low. It is more likely that the gas syringe was faulty. Due to this, there was not much of a reaction. ...read more.

Conclusion

Also I would increase the time in which I record the reaction to see if more changes still occur even after the main spurt of acceleration of the reaction because it is likely that some reactions are still occurring, unfortunately they are likely to be invisible to the naked eye, due to their minute sizes. Nevertheless, I am still satisfied with my initial results and do not see any need for me to change my apparatus or my independent variable. Furthermore, in order to perceive a superiorly high degree of meticulousness, a severely more accurate method of measuring the surface area of the fragments of potato would have been compulsory in order to comprehend that all the surface areas were the same for each test. I strongly believe that if I had better equipment to conduct my experiment, I could have induced more accurate results. This is because my equipment wasn't in perfect condition as they have been used extensively before. For example, the gas syringe which I made use of in my pre-test which unfortunately, turned out to be horrifically defected. The goggles also made it considerably difficult to see as there were many scratches on them which could definitely have impeded some vision; consequently this could have led to someone miss-interpreting the measurement of the liquid or the distance of a fundamental object. It is also very likely that something of this calibre could lead to an individual spilling hydrogen peroxide which would be very catastrophic and dangerous. Lastly, I defiantly believe that there should have been another way in which we could have fed the fractions of potato into the boiling tube to stop any slight risk of potential oxygen that is being produced, to be wasted and released. This was a key factor as this could have changed the whole dynamics of the experiment, and we would have been none the wiser. ?? ?? ?? ?? ...read more.

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