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To investigate what affects the rate of which catalase decomposes hydrogen peroxide.

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Aim The aim of our investigation is to find out what affects the rate of which the catalase decomposes Hydrogen Peroxide. Introduction The reaction between the substance (Hydrogen Peroxide), and the catalase (potato), produces water and oxygen. Hydrogen Peroxide catalase Water + Oxygen 2H2O2 catalase O2 Variables There are 8 variables that we could have used. These are as follows: - * Temperature * pH * Concentration of enzymes * Concentration of substrates * Type of potato * Age of potato * Size of the cylinder of potato * Raw or cooked potato The variable that we have decided to use is temperature, and I have put a little star next to it. We decided to use this because we thought it would be the easiest, and most accurate possible. We were thinking of using pH as our variable, but we decided that it was too difficult to do and that it is more than A* grade work. Prediction I have predicted that the more the temperature is increased, the faster the rate of reaction will be. I think this because the molecules will leave and enter the active site faster. I also think there will be more successful collisions meaning that there will be more bubbles produced. ...read more.


First of all we will collect all of the apparatus required for our experiment. 2. Use the cork borer to get 6 cylinders (1 spare) of potato. 3. Now that we have the 6 cylinders of potato, we need to cut them all to the exact same length using the scalpel. 4. Put 1 cylinder of potato into each test tube, leaving us with the spare piece, in case something goes wrong. 5. Now put 25cm3 of Hydrogen peroxide into each of the 5 boiling tubes 6. Now fill the 5 100ml beakers with there specific temperature of water. 7. Now put a test tube with potato in, into a beaker of water along with a boiling tube with Hydrogen peroxide in it. 8. Wait until the potato and Hydrogen peroxide have reached the temperature of the water that they are in. 9. Once they have reached the desired temperature, put the potato into the hydrogen peroxide, and immediately place a delivery tube on top. 10. Start the stopwatch, put the end of the delivery tube into some water, and count the amount of bubbles produced in the water for 3 minutes. 11. After 3 minutes is up, record the amount of bubbles produced into a results table. ...read more.


This is due to the fact that the active site will be totally denatured. Before we started our experiment we predicted some results and compared them to our actual results. They were reasonably close. Evaluation Overall, our results were accurate and in my opinion we chose the correct variable to use. We eliminated all of the variables apart from concentration of the catalase, which we were unable to control. I think our experiment was very well done and our results were very accurate. We were sure that our results were accurate as we repeated the experiment twice and we got roughly the same results each time. We had one anomalous result from our experiment. This was when there were 32 bubbles produced from a temperature of 400. There may have been a leak in the delivery tube that caused this to happen. To make sure that our results were definitely accurate we could have repeated the experiment for a third time, but we did not have enough time. A different type of method that we could have done was to collect the gas in a gas syringe instead of counting bubbles. This way might have been more accurate but we would have had a problem when the gas syringe was full, we would have had to empty it. From my prediction, I was not correct in predicting that the hotter the temperature, the more bubbles were produced. I know fully understand why I was incorrect. ...read more.

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