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The Effect Of Changing The Surface Area Of Potato On The Breakdown Of Hydrogen Peroxide.

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The Effect Of Changing The Surface Area Of Potato On The Breakdown Of Hydrogen Peroxide In this investigation, when reacting the catalase enzymes with the hydrogen peroxide, what is produced is oxygen and water. We shall only be paying attention to the oxygen being produced, and that is the variable to be measured. The surface area will be that of the sides of potato CUBES. Equipment * 1 Gas Delivery Tube * 1 Container * 1 Measuring Cylinder (50cm2) * 1 Boiling tube * 1 Timer * 1 Potato cutter and knife * 1 30cm ruler * 1 bottle of hydrogen peroxide Safety * Through out the experiments we will be wearing safety glasses because we are dealing with an oxidizing agent. * Standup through out the experiments, we can quickly move away if we are in any danger * Never run in the lab * Put all bags under the table to make sure no one falls Prediction I predict that as I double the surface area, the amount of oxygen gas produced shall also double. This means that the amount of oxygen produced is directly proportional to the surface area of potato. A straight line going roughly through the origin shall prove this. I predict this because when the quantity of catalase enzyme (which is on the surface of the potato cubes) is increased, by increasing the surface area of potato, this means that there are more enzymes to react with the hydrogen peroxide (the substrate of this reaction) in the same amount of time. Also according to the collision theory, with more enzymes in the same volume of hydrogen peroxide there is a higher probability of successful collisions between the active site of the catalase enzyme and the substrate (hydrogen peroxide) and therefore with a higher rate of successful collisions then there is more hydrogen peroxide being turned into oxygen (and water) ...read more.


Volume of Oxygen (cm3) 48 17 72 19 96 21 120 41 From these tests I found that 120cm2 produced 41cm3 of oxygen, since we are using a 50cm3 measuring cylinder, using a higher surface area then this could cause problems if it exceeded 50cm3, hence I shall use this as the maximum surface area. I noticed, that at 72cm2 and above the cubes started to clump together, which means that many sides of the cubes were blocked, and hence many sides full of catalase were not reacting with the hydrogen peroxide. Also, from 72cm2 and above since the boiling tube in which the reaction was being carried out was small, the froth of the reaction started to be sucked through the gas tube, and end up with the oxygen in the measuring cylinder. This affected the results, and hence that's why we have such a big gap in volume of oxygen produced for the surface areas 96cm2 120 cm2, since the froth took up a large space. I shall use the surface areas 48 cm2, 72 cm2, and 96cm2 as the 3 medium surface areas to test. This is because they don't produce too much froth, and the clumping is also not so much, it gets worse as the number of cubes is increased. Now I must decide how to measure the oxygen gas being produced. I can either count bubbles emitting from the delivery tube, or I could use a measuring cylinder to measure the volume produced in cm3. The problem with counting the bubbles is, that it can not be made accurately sure whether the volume in each bubble is the same, and secondly, some bubbles may be missed or miscounted if the rate of bubbles emerging is really fast, both of these disadvantages make the bubble technique extremely inaccurate. Therefore I choose to use the measuring cylinder to measure the volume of oxygen gas in cm3 displacing the water in the measuring cylinder. ...read more.


If given time I would like to carry out the same experiment, but with an improved method, for accurate results. We could solve both these problems, and bring the clumping to a minimum if we were to use a conical flask. The increased size at the bottom of the flask should put clumping to a minimum, although, since the bottom cubes would have one side, on the base, we would still have a decreased surface area in the practical then we'll want. Also, with this method, the foaming problem should not take place since the conical flask is bigger, and can hold a larger volume of substance then the boiling tube. There is also another way, since we are only interested in the catalase enzymes on the potato, if we could get a simple solution of catalase enzymes, we would have no problems whatsoever with clumping. This solution can be pancreatic juice, since catalase enzymes are found in there, they are also found in the liver and saliva, to break down hydrogen peroxide. Then with the conical flask method, if given time I would like to develop my investigation by trying much higher surface areas, to see if the volume of oxygen being produced levels off because of clumping, and also to see if there are any laws or limits I might encounter. I could do this if I were to try higher surface areas: 150 cm2, 168 cm2, 186 cm2, 205 cm2, 223 cm2 and then compare those results with the results from this investigation, and then I can see if there is any drastic change of pace in the graphs, which would tell me that there is a law or rule present. I would also like to try to investigate how other enzymes affect the volume of oxygen produced from hydrogen peroxide, when reacted with a constant surface area of potato, containing catalase enzymes, and how it affects the amount of oxygen produced. kat8984984 Khalid Khan 11U Doha College ...read more.

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