The collision theory states that molecules must collide with sufficient energy (activation energy) if a reaction is to take place. As temperature increases more molecules gain this activation energy, hence more collisions occur per second, so the rate increases. This is what will happen in my experiment. The product will be the carbon dioxide produced. I believe the rate of reaction will be at its peak when used in conjunction with water at a temperature of 40?
C, because if the temperature exceeds this then the enzyme is also not efficient due to the lock and key hypothesis, which states, when an enzyme gets to a certain temperature, it denatures and cannot function properly. Apparatus The apparatus I will be required to use in this experiment are a: Conical Flask (plus cork) Measuring cylinder (Cylindrical) Borer Delivery tube Water Water bath (room temperature, 30? C, 40? C, 50? C and 60? C) Knife White tile Ruler Variables Stop watch Bung The variables used in this experiment will be: The varying temperature of the water The volume of H2O2
The amount of Potato (for this experiment we used #cm as if we used a certain weight rather than length, the surface area would be different for each piece, so therefore making the test unfair. The shape of the potato (again to do with the surface area) The time of the reaction so as to gain the correct readings from each test. Apparatus and Diagram Method Firstly we gathered together the above apparatus and set up the experiment as shown in the diagram. We would use 2, 3cm size pieces of potato for each test tube and carry out each individual test 3 times and gain an average reading.
The tests would involve testing the reactivity with 5 different water temperatures, these temperatures: Room temperature, 30? C, 40? C, 50? C, 60? C We decided with the experiment that we would time the reaction for 1 minute and then note down the reading of oxygen (O2) produced. To insure that the temperatures were at their exact point and to make sire the we stable, we used water baths, which heat the water to the exact temperature and keep the temperature constant, as to make the test a fair one.
As with all experiments, we had to be aware of safety, for a number of reasons: We were using a knife to cut up the potatoes, which, when being used wrongly could lead to injury. H2O2 is a corrosive substance, so we had to be careful that we did not come in direct physical contact with it (i. e. spill it on our skin) and finally, We were using a water of high temperature (50 and 60) so had to be careful not to burn ourselves. Table of Results Temperature (? C) Test 1 (O2 produced in cmi??
) Test 2 (O2 produced in cmi?? ) Test 3 (O2 produced in cmi?? ) Average (cmi?? ) 20. 0 (room temp) 1. 20 0. 80 0. 90 0. 96 30. 0 1. 40 1. 80 2. 00 1. 73 40. 0 2. 40 2. 60 3. 10 2. 70 50. 0 1. 80 2. 00 1. 50 1. 76 60. 0 0. 07 0. 09 0. 10 0. 086 Summary of Results You can see from the results, the reaction rate slowly increases as it goes from 20 to 40 and at 50 it has begun to denature, but by 60 the enzymes have completely denatured and the reaction is very small. Conclusion
The scientific knowledge we gathered during our theoretical side of the experiment proved to create results that we easily distinguishable when plotted against what we had predicted to find. For example, the lock and key hypothesis states that once an enzyme has reached a certain temperature beyond its optimum, it becomes denatured and cannot function properly as a catalyst and therefore not speed up the reaction. The collision theory also comes into the experiment, as with a greater volume of H2O2 the experiment rate of reaction would increase.
This is due to the fact that with a greater volume, there will be more successful collisions between both reactants. To conclude the practical experiment, we found that due to the enzymes being biological, they denature once they reach a certain high degrees, and we found the reaction decreased severely between 40 and 60. This suggests that the enzymes began to denature somewhere before 50. We also found that the results reflected the theoretical calculations we had made earlier (i. e. the collision theory: Rate = Change in Volume/Time)
This also suggests that if we used a greater volume of H2O2 then the rate of reaction would speed up (e. g. in this experiment the rate of reaction was directly proportional to the rate of reaction. ) Evaluation The aim of our experiment was to see whether temperature has an effect on catalyse activity, from my results we can see that it does. The procedure of this experiment was fairly straight forward and was carried out correctly though there were certain things that complicated the practical side of it.
The quality of the data we obtained was if not perfect, close to correct as it approximately fitted with our theoretical predictions that after 40 the enzymes would begin to denature and by 60 they would be completely ineffective in the reaction. With most experiments like this one, there are always going to be certain factors that either arent carried out properly or are not going to work quite as they should in a classroom atmosphere, as it is far different from a scientific lab, but I feel that the experiment was suitable and we received good, accurate results.
There are a few improvements that could be made to improve the fairness and accuracy of the experiment. For example: Use either a more accurate water bath, or other device that can heat to a certain temperature and keep that temperature at a constant level. And Use a more accurate instrument (rather than a knife and ruler) to cut out the potatoes to insure they are all of exactly the same length and surface area, to keep the test fair. Another thing I would have done is use a pureed potato instead of using a potato cylinder like I did. This is because it would give more active sites for a reaction to take place.