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Aim: This experiment will aim to show how the amount of substrate affects the rate of the reaction. Hypothesis: In this experiment I think the amount of substrate will simply increase the reaction. As I increase the surface area of the potato the gas given off from the reaction will increase. Therefore to sum things up, my hypothesis is when the Independent variable increases so will the dependant variable. Independent variable: -Surface area of potato Dependant variable: -Gas Controlled variable: -Equal size of potatoes used -Using measuring cylinder
Equipment used: -Gas collecting kit -Potato -Stop watch -Test tube -Distilled water -Hydrogen peroxide -Knife Safety precautions: Dealing with corrosive chemicals “hydrogen peroxide” Method 1. Cut potatoes into 9 equal pieces. 2. Peel off skin. 3. Cut each potato chip into ascending order. 4. Add buffer of 4. 8 ml. 5. Add 1. 4 ml of hydrogen peroxide 6. Add potato chip & close bung. 7. Take measurement of gas after 2 minutes. 8. Repeat. Investigating the effect of enzyme concentration on the rate of an enzyme-catalysed reaction. James Moore Conclusion: For the conclusion we see that in fact the hypothesis is correct. When independent variable increases so does the dependent variable. As the amount of enzyme concentration increases so will the rate of the enzyme catalysed reaction. In the human body substrate is always available therefore there is only one possibility and that a constant increase in the rate of reaction. When there is higher enzyme concentration there will be more active sites available so therefore more oxygen will be given off from the hydrogen peroxide.
Reaction occurs in the active site therefore it is evident that as enzyme concentration increases so will the rate of the reaction. This is proved by the graph as we can see that it does not plateau but the rate of reaction continues to increase no matter what. As we can see from the table of results; as the surface area increases in each test tube so does the rate of reaction. As surface area of the potato was increased the amount of gas collected after two minutes increased rapidly. Evaluation:
Overall my experiment was set out to be quite fair as I did the experiment three times to get an average. However there were anomalies in this experiment as seen in the table of results that there was a big time difference when two pieces of potato was used. In this experiment I tried to make sure that it was a fair test. I used a ruler to accurately cut my potato in equal chips and then cut the individual strips into pieces I needed from a range of 1-12. I was unable to complete my recordings due to lack of time so I used Hyun Jins results.
Originally I was going to measure the amount of gas after two minutes. I also changed the strength of hydrogen peroxide from 85% to 70% as the first time I carried out the experiment the bung blew off the top of the test tube. I also reduced the amount of liquid used in the test tube. Despite the effort to get a fair test and result there were some anomalies; these may have been due to a number of things: -The potato sizes weren’t accurate enough -Potato skin may have still been left on a little bit The buffer measurement was inaccurate -Measurement of time was inaccurate -The same pipette was used -Measurement of liquid may have been different In order to prevent some of these anomalies in the future I should be more accurate in measurement & ensure that the pipette used were specific to the chemical I was handling. ? Table of results: Enzyme concentration (pieces of potato) Time taken for 10ml of Oxygen to form (seconds) Trial 1Trial 2Trial 3Average 2105720168331 4391666590 617643639 815462729 1025323731 1214232721 ?