Justification: Enzymes convert these molecules upon which they work (substrate molecules), using a specific method.
As enzymes are known as the biological catalyst, we understand why they themselves do not get used up when converting substrates.
Every enzyme has an active site where the substrate molecules join to the enzyme molecules to form a product molecule.
Every enzyme has a specific shape for a specific substrate to fit into and start functioning; this is why enzymes do not work in conditions that denature them.
The equation below shows the reaction that takes place when catalase is added to hydrogen peroxide.
Method
Apparatus:
- 14 Boiling tubes
- 3 boiling tube racks
- 1 water bath
- 1 thermometer
- 1 stop watch
- Yeast catalase solution
- Hydrogen peroxide solution.
-
1 fifth teen cm3 syringe
- 1 clamp stand
-
1 hundred cm3 gas syringe
- 1 volumetric flask
- 14 label tags
Procedure:
- First label each boiling tube to state the solution of which it will contain and the temperature they will be exposed to, this should be done for both the catalase and hydrogen solution.
- Now make the boiling tubes to stand in a section of the rack.
- Now that the boiling tubes have been labelled with the appropriate information, fill 7 of the tubes with 15cm3 each of catalase solution and the other 7 with 15cm3 of hydrogen peroxide.
- Set up the gas syringe and the clamp stand as shown on the next page
- Put the last
In order to ensure this experiment is conducted in a accurate and fair manner, I will heat both the catalase and hydrogen solution in the same water bath at the same time, with one thermometer in each tube keeping the monitoring the heat change, this way the slightest change in the temperature of the two solution will be observed.
Will also put each thermometer in a beaker of ice cold water before I put the in the actual solutions so this way I can observe the exact escalate in temperature.
Safety precautions:
- Take extra care when handling the hydrogen peroxide solution, as it is a poisonous substance.
- Label all the boiling tubes by the temperature of which they will be heated to avoid confusion.
- Be careful not to inhale any of the gas fumes released from the reactions, as it may prove harmful.
- Follow the general laboratory rule i.e. tie long hair back, place bags underneath tables, no running etc…
Bibliography:
Advance biology
Endorsed by Nelson
Biology 1
Endorsed by OCR
Results:
The following were kept constant:
- Concentration of hydrogen peroxide (%)
- Concentration of yeast catalase (%)
- The volume of hydrogen peroxide used (15ml)
- The volume of yeast catalase (15ml)
The table that follows displays the results of the effect of increasing temperature on the reaction between enzyme catalase and hydrogen peroxide reaction.
Only one result of each temperature was taken and recorded. This was due to the limited time that was available; I was unable to progress with another experiment, which would have allowed me to average out my results. Never the less the results I have gain at present seem both legitimate and reliable enough to draw a satisfactory conclusion.
3. Analysing of evidence (and drawing conclusions)
Graph 1
This graph illustrates the relationship and trend gained when the temperature of enzymes catalase is increased.
This graph basically shows us that from a low temperature, the time taken to get to 50ml will simultaneously be increased via the raise of heat applied, this will continue until the temperature becomes too extreme for enzymes to work sufficiently. Therefore the time will eventually decrease in speed, and takes longer to get to 50ml until it finally stops. Although the graph supplies us with all the information stated above, it does not specify the realationship between the temperature and the rate of reaction. In order to find the rate of reaction (the speed of which the product is produced) there is a special formula to follow.
Rate: volume of gas produced /time or in this case 50/time
This table below displays the results of the same experiment, but with and extra column representing the rate.
I have rounded the figures to 2 decimal places to make the plotting of the graph a lot easier and uncomplicated.
The second graph shows the rate of reaction plotted against the temperature.
Analysis/ graph 1
This graph demonstrates to us how the rate of a reaction varies with temperature. The sort of V shape displayed on the graph shows us that as temperature is increased the time taken for 50ml of gas to collect in the syringe will decrease until the optimum temperature is attained (which in this case would be the bottom of the v shape) at which point the time will increase again and eventually stop. This routine pattern was what I predicted in my hypothesis.
The scientific knowledge behind this reaction was explained a clarified in my justification for the predictions; this reaction also compliments the collision theory.
The time taken for the gas released to collect into the syringe increases as the temperatures increases. This is to the fact that as the enzymes are heated they become energised and start to vibrate at a constantly accelerating pace. This means that there are more chances for successful collision to take place, hence making the reaction quicker every time the heat is intensified.
So as temperature is increased, it takes a shorter time for gas to collect in the gas syringe, this is the case until the optimum temperature is overcome, there the time will decrease and get slower as it takes longer for gas to collect in the syringe.
Graph 2
This graph illustrates very clearly how temperature affects the rate of reaction. It is also evident that the predictions made before the experiment was carried out, are more or less reliable. Increasing the temperature means increasing the amount of energy each particle has, so there are more chances for collisions to take place, via the brisk movements of the molecules amongst each other. I think it is safe to say that the rate is directly proportional to temperature with the results gained in this experiment.
Evaluation Of Evidence
Accuracy:
Even though the result I have obtained from this experiment authenticate a reasonable graph for rate against temperature, and also allows a satisfactory conclusion to be drawn, the results are not perfect.
As I was only able to carry out each experiment for each temperature once, I was unable to gain an average result, which would’ve help in the sense that if one trial was bogus, the other trial could’ve given me a mean end result.
Another thing that could’ve affected the results was the delay between the mixing of the two solutions, and the coving up of the volumetric flask with the bung to start timing the reaction. Due to my working alone, it proved difficult to put the bung on the flask and start the stop cloak at the same instance, so there is no bout in my mind that some gas would’ve been lost within that short space of time. This maybe could’ve even affected the pattern of the trend on the graph. On that note, we must acknowledge that the same procedure and measures were taken for each temperature, so for each trail there must have been a delay of some sort, therefore consequently if we look at the positive side of things, we should really appreciate the fact maybe the same amount of gas was lost each time the delay occurred.
Another slip-up that may have affected my result was maybe excess solutions left in the boiling tube after I have combined them together to start reacting. During the experiment I put the heated yeast catalase in the volumetric flask first, then I submitted the also heated hydrogen peroxide to start the reaction. At time I was in such a hurry to add the hydrogen (so the catalase wouldn’t lose lots of heat) that some solution may have been excess in the boiling tubes. If this is true it means that some of the experiments carried during the investigation did not have exactly 50ml of each solution, thus implying that there weren’t equal amount of molecules available some reactions.
One more thing that could’ve affected this experiment is evaporation. We all know that when fluids are heated, depending on the temperature it’s exposed to, they evaporate into the atmosphere. Although I did not pay very much attention to see if vapours were being released, there is a slight chance that if this was the case some solution might have been lost via the fumes.
Improvements: Although my results are logical, there are several things that I could’ve done to improve the accuracy of the corollary I achieved and I have stated below:
- Repeating the experiment for a second time so an average of the results could’ve been obtained.
- This would’ve helped me to show accurate my first results were, because I would be able to compare them to my second one. It also would’ve given me a mean of the results, so in case both outcomes were of the mark, I at least could’ve got a solution for the problem through the middleman.
- Another problem was the delay that consistent between the mixings of the two fluids and the adding of the bung to start the timing the reaction.
-A way that this problem could’ve been avoided, was if there was another person helping me during the experiment, so one individual can be starting the stop clock and another could be putting the lid on the flask. However, after reviewing that idea it occurred to me that there would still be a delay regardless. The only improvement would be the shorter time length it would take to add the bung on the flask.
-It became clear that the only way I could rid of this problem would be to get an apparatus where the bung doesn’t have to be removed from the volumetric flask, yet the solutions can still be combined and mixed and the gas given off can still be measured by the gas syringe. For instance, if the bung had two holes intended in it, were one hole was connected to a tap, which would release the hydrogen into the catalase, and the other connected to the gas syringe, which would collect the gas discharged. This process would surely affect the accuracy and reliability of the results.
Reliability
My conclusion is: Rate oo temperature
Being that the shape of my second graph is just as I had predicted and explained, I can confidently say that the results of the experiment supports my hypothesis very well and is really quite reliable.
Further investigation:
As we know there are several things that affect the rate of reaction and temperature is just one of them. If I were to further investigate how the rate of a yeast catalase reaction could be affected, I would probably investigate concentration. It would be interesting to see how increasing the amount of particle available can affect the speed of a reaction.