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An investigation into the effects of substrate concentration on an enzyme reaction between catalase (potatoes) and hydrogen peroxide.

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An investigation into the effects of substrate concentration on an enzyme reaction between catalase (potatoes) and hydrogen peroxide. Prediction. I predict that if you increase the concentration of Hydrogen Peroxide, the speed of reaction will also increase but the rate of reaction will always slow the longer the reaction takes place. Background knowledge Enzymes speed up reactions but are not used up in the reaction so they can be used more than once. Enzymes are a biological catalyst made of protein molecules, all living organisms have, and need enzymes to live without them chemical reactions in the organism would take to long and the organism would die all enzymes are affected greatly by theses two conditions temperature and the Ph level, at low levels the enzyme works slow, this is because there would be less energy at a cold temperature so as the molecules are moving slower the number of collisions in a set amount of time would be lower than at a high temperature also there would be less of the energy needed for a collision to cause a reaction. When the temperature increase the rate does but at to high of a temperature the protein molecules making the enzyme denature and they stop working. ...read more.


2 Fill 6 test tubes with 20cm3 hydrogen peroxide each one containing a different concentration, below in actual experiment method are the concentrations. 3 Put the chosen size of potato into the conical flask. 4 As soon as you add one of the test tubes of acid place the bung on. 5 Start the clock. 6 When you have collected When you have collected 5cm3 of gas, stop the clock 7 Record the time 8 Wash the equipment and repeat the experiment with a different strength acid. 9 When you have done all 6 acids, repeat the above but this time collect 10cm3 of gas. Results Concentration of H2O2 Amount of acid Time for collecting 5cm3(S) Time for collecting 10cm3 (S) 100 20 82 224 80 20 127 236 60 20 148 280 40 20 158 264 20 20 276 336 0 20 No reaction No reaction Preliminary conclusion I have decided to collect 5cm3 of gas because with the limited time I have to do the experiment the 10cm3 of gas would take a lot longer to do then the 5cm3 and I might run out of time or have to rush, which could result in mistakes being made. ...read more.


and so the rate of reaction would lower, to prove this I would have to repeat the experiment leaving the H2O2 and potato to react for a longer period of time. The reliability of my experiment is good but not perfect and the major source of error, is most likely to come from human error. I also feel that errors could come from the potatoes as different potatoes have different amounts of water in them, their could be a gas bubble in the measuring cylinder which would throw out the results and so have a different mass. I could improve my experiment by removing the bung an replace it with a self sealing bung this would lower the chances of gas escaping, I could also replace the measuring cylinder with a gas syringe which would improve the accuracy of the results and therefore not allowing gas bubbles to be present which could affect the results, I don't know what to do about the different concentration of water present in the potato as drying or cutting could affect the amount of surface area which would affect the results. To improve the experiment further I could go up in 10% concentrations of hydrogen peroxide to add more results and so increase reliability of the experiment. ...read more.

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