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Investigate: To determine the relationship between surface area and rate of oxygen production when potato tissue is placed in Hydrogen peroxide solution

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Introduction

Investigate: To determine the relationship between surface area and rate of oxygen production when potato tissue is placed in Hydrogen peroxide solution Planning My prediction I predict that the bigger surface area of the potato chips, the faster the rate of reaction of the hydrogen peroxide is being use up and the faster the oxygen is being given off. Also the rate of the oxygen being given off should be directly proportional to each other. Scientific Theory Catalyst is one of the factors which affect the speed of a reaction. Enzyme is one type of catalyst and catalase is an example of enzyme which I will be using in my experiment. Enzymes works because they cover in active sites which is more specific about molecules they will allow to stick on. It is often describe as a lock and key mechanism. In this experiment the lock is the catalse enzyme and the key is hydrogen peroxide. Diagram to summarize how does the surface areas affect the rate of gas coming off Key: H2O2 Arrows mean H2O2 diffusion into the potato tissues. H2O2 H2O2 H2O2 H2O2 The word equation of this experiment is: catalase Hydrogen peroxide Water + Oxygen catalase 2H2O2 2H2O + O2 Method * I will be given a potato and I will cut the potato chips from chip cutter. ...read more.

Middle

This means that comparatively milder collisions will now have enough energy to over come the activation energy barrier. Enzymes are large molecules and proteins. Each different enzyme has its own special shape. The reactants fit into the enzyme, like a lock and key. The reactant slots into enzymes at its active site Diagrams to summarize how does enzymes work Other enzymes can build up big molecules from small ones. Reactions go faster in higher temperature because of the catalase molecules will be moving faster and will therefore collide were often and harder and both of these factors will speed up the reaction. But if the enzyme gets too hot, it changes shape. So the reactants will no longer fit snugly into the enzyme's active site. It can't catalyse the reaction because the enzyme is denatured. Enzymes work the best at around 40�C because they are proteins which are damaged by temperatures above about 40�C. Also they work best at a pH 7 because they are proteins which are damaged by very acid or very alkaline conditions. I have seen in my graph as my surface area of my potato chips increase, the volume of the oxygen collected is increased. Therefore the bigger surface area of the potato chips, the faster the rate of reaction of the hydrogen peroxide is being use up and the faster the oxygen is being given off which is I predicted before I did the experiment. ...read more.

Conclusion

From looking the results and the graph I got of the first experiment, I found out there have lots of anomalous results, so I decided to do a repeat experiment and my results were pretty accurate in my repeat experiment. I could draw the best-fit lines easily and the readings were pretty close to my trends. But there is still one anomalous result which is in my fourth chip at the 3.5 minutes. The point was too low as I was expect, this maybe because the potato chips were stick together or the cell membrane was damaged before I did the experiment or maybe I had miss read the reading on the burette, if I have a chance to do the experiment again I will make sure I read the burette carefully. When I looked at my rate of reaction all the points were very close to the trend. I think I had sufficient readings to produce a firm conclusion as I have a range of 5 sets of readings already. But in order to make it as accurate as possible I can carry out another experiments by using different kind of cells such as liver and use a different concentration of hydrogen peroxide. To do that I can use the same method to cut the potato chips to cut the liver and put them into 0.8M hydrogen peroxide instead of 1.7M. Also I can take the readings more frequently by taking them every 15 seconds instead of 30 seconds. Amanda Tam 17/10/01 Chem+Bio coursework ...read more.

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