Filled another test tube with water which it will be used for counting the bubbles.
Once the required temperature was achieved, 5 disks of potato (each cut to 2mm) were added to test tube. Attached the delivery tube to the tube with hydrogen peroxide and potatoes and the end of delivery tube was in the tube filled with water earlier (Figure 1). Counted the number of bubble for the duration of one minute and recorded the number. Did the same thing three times for each temperature.
Figure 1
Result and Diagram:
Conclusion:
As we expected the increase in temperature increased the rate of reaction till it was higher than optimum temperature were the heat would start to denature the enzyme and it would slow down the activity.
Discussion:
Enzymes are substance that speed up a chemical reaction and are used in body to lower the activation energy. Without enzymes none the chemical reactions that happen in cell would have happened in normal cell condition. Enzyme work by binding to the substrate at active site, this is called lock and key. So if the active site change shape means that enzyme can’t bind with substrate and there wont any reaction. Each enzyme has a specific active site shape which makes it specific for one reaction and wouldn’t be any use in other reactions.
Rising temperature would increase the active energy in molecules and reaction between them would become faster and it has been mentioned that an increase of 10oC would almost double the rate of reaction but in enzyme-catalysed reactions things are different. As temperature increases the substrate and enzyme molecules would move faster and there is higher chance of them to collide with each other and as a result the rate of reaction would rises, as seen in this experiment. But enzyme would denature by heat and as we increase the temperature the rate of denaturing would increase. This change is permanent as heat would change the active site of enzyme. So as the temperature increases there are less and less active enzyme which it cause on lowering the rate of reaction.
So it can be seen in the graph that the high and low temperature has denatured the enzyme and resulting in slowing down the reaction but in between the increase of temperature increased the rate of reaction till the optimum temperature. The temperature that the rate of reaction would stop increasing by increasing the temperature and would start going down again is called “optimum temperature”.
One of the problems that we had while doing this experiment was, once we made sure that we achieved the right temperature than we took the test tube out of ice bath or water bath. This resulted that the hydrogen peroxide wouldn’t have the right temperature while doing the experiment and not getting good result. So we had to repeat some of the tests but this time make sure that hydrogen peroxide reaches the required temperature and it stays in that temperature while counting the bubble.
