Investigating the Effect of Temperature on the Catalse Controlled Breakdown of Hydrogen Peroxide

Investigating the Effect of Temperature on the Catalse Controlled Breakdown of Hydrogen Peroxide
Experiment to investigate how the change of temperature affects thecatalase controlled breakdown of Hydrogen PeroxideplanningBackground KnowledgeAn enzyme is a biological catalyst, it alter the rate of reactionwithout being changed itself. Enzymes are protein molecules; they havea very precise three-dimensional shape, which forms a one specificactive site on the enzyme. Enzymes can only catalase one reaction ortype of reaction, they are specific. Enzymes are affected bytemperature (Enzymes stop working if the temperature rises above 40?C.Increasing the temperature alters the 3D shape and so the enzyme canno longer fit the substrate) and pH (They work best in neutralconditions neither acidic nor alkaline).
Equipment ===== Core Borer Potato 4 boiling tubes 125 ml Hydrogen Peroxide Ice cream tub, half filled with water of room temperature Two wooden Blocks Clamp stand Thermometer Beaker Bunsen Burner Bung and delivery tube Test tube Test tube rack Stopwatch Knife Tile Ruler Measuring Cylinder Heatproof mat Matches Goggles Lab Coat Method ==
Using the Core borer bore out five pieces of potato from the same
potato. Cut these pieces into lengths of 4cm on a tile, using a
knife and a ruler.
Measure out, using a measuring cylinder, 25ml of Hydrogen Peroxide
into each boiling tube. Place the four boiling tubes on to the
test tube rack.
Set up the water bath (ice cream tub) as above, with the delivery
tube on the bung leading through the water and into a test tube.
Raise the water bath on two wooden blocks.
For each experiment, heat to required temperature using the Bunsen
burner and set up as below with the thermometer in the hydrogen
peroxide to record the temperature. (Or for room temperature
sample, test temperature of liquid before placing the potato in).
When the boiling tube of hydrogen peroxide has reached required
temperature, quickly place one of the potato pieces into the
hydrogen peroxide and place the bung on, ensuring that the
delivery tube and the test tube are in the correct positions.
Start the stopwatch and hold the bung on the boiling tube firmly
and count the bubbles that come from the end of the delivery tube
into the test tube. Every minute on the stopwatch, record the
count of these bubbles as an accumulative total and continue
recording the number every minute for five minutes, record the
number on a results table.
Repeat the above experiment for all four temperatures and then for
each temperature repeat a further two times so that for each
temperature, there are three results.
After the five minutes have finished, remove the test tube and
throw away the liquid and the potato and add any water to the
water bath if necessary (if the water level has gone down
significantly). Set up the experiment again and repeat.
In the experiment the following were done to ensure a fair test and accurate results: ? To use the same potato, as a certain potato may be easier to break down than another for any reason. ? The surface area of the potato, by using the same core borer of diameter 8mm and cutting the pieces into the same lengths, the surface area should stay roughly the same. ? The same size equipment e.g. boiling tubes as the readings for the results will be wrong if this is not constant ? Use the same method for each experiment so that there won?t be any major differences. ? Only alter the temperature. ? Measure the temperature with a thermometer ? Equal volumes of hydrogen peroxide ? Do the experiment three times to ensure that there isn?t an odd result. Three is a good number to use as you can see if there is one odd one where if you just done the experiment twice then you wouldn?t know which one odd and which isn?t. ? To average the results. ? Use same width tubing on the delivery tube, as this may cause the amount of bubbles to be interrupted. Safety Precautions ======
Wear safety goggles
Wash hands after dealing with hydrogen peroxide (it is corrosive)
Wear lab coat
Keep Bunsen burner flame on safety flame when not in use
Predictions and Reasons ======= From my research I think that the enzymes will denature after 40?C and any other temperature above that. Enzymes are proteins and their structure is three-dimensional. Increasing the temperature disturbs the intra molecular bonds that hold the 3D shape. Because of this the shape is altered. Enzymes have an active site. This fits into the substrate molecular. If the active site is altered the substrate will no longer fit in and so the enzyme doesn?t work properly. The rise of reaction rate is also due to the increase in temperature, relating to the movement theory. The higher the temperature, the faster they move. This happens but only to the highest temperature of 40?C. The curve leading up to the optimum point is gradual but as it is reached it would fall dramatically. The reason being that the active site is destroyed therefore no reaction can take place as there is only one specific active site per substrate. Previous Experiment When carrying out a preliminary experiment, I found that using 25ml of hydrogen peroxide was best as it wouldn?t let the froth rise to the top of the boiling tube and would speed up the reaction to fit within 5 minutes. I chose the length 4cm for the potato because when boring the potato, most pieces could be cut down to that size and also so the potato will be fully immersed in the hydrogen peroxide. I also found that 5 mins would be sufficient time to carry out the experiment. I had intended to also do an experiment with 60?c but the preliminary experiment showed I would not have time to do all the temperatures I wanted to and the trend that 40?c and 50?c set would only be continued by 60?c and so the 60 ?c results were not crucial and therefore could be sacrificed for the sake of time. The potato is acting as a catalase, catalasing the reaction of the breakdown of: [image] Hydrogen Peroxide Water + Oxygen Room Temp. (18?c) 30?c 40?c 50?c 1 minute 32 51 53 44 23 42 48 49 22 28 30 19 Average: 26 40 44 37 2 minutes 60 99 111 104 51 90 100 99 41 55 50 24 Average: 51 81 87 76 3 minutes 83 143 155 136 74 137 145 143 38 78 64 34 Average: 65 119 121 104 4 minutes 104 184 200 164 96 180 190 174 74 95 74 41 Average: 91 153 155 126 5 minutes 123 222 230 183 115 222 227 194 90 112 80 52 Average: 109 185 179 143 obtaining evidence Key ====== 1st experiment 2nd experiment 3rd experiment Average of three experiments [image] [image] [image] [image] [image] Looking at my results, I can see that most of my results would fit a line of best fit and there does not seem to be any real anomalies. The only strange result is in the third experiment, the 50?c results are considerably lower than the other three temperatures which goes against my prediction: as the temperature is increased the rate of reaction is increased. The rest of the experiments show this. The curve of the total amount of bubbles shows a peak earlier than anticipated, at roughly 35?c, but the shape of the curve is correct and as expected. analysing ===== Trends == I have found that as the temperature is increased to 40?c, the rate of reaction is increased, if the temperature increases beyond 40?c the rate of reaction decreases, this is because the enzymes are starting to become denatured. Nearly double the bubbles (oxygen) was produced when the temperature is increased from room temperature to 30?c, I have also found that generally at the start of the experiment more oxygen is produced than at the end where less is produced. Most oxygen seems to be being produced in the first two minutes because at this time there is more catalase particles for he hydrogen peroxide to react with than later on. After five minutes, less oxygen is produced because at this time there is less catalase particles for the hydrogen peroxide to react with, causing a slower reaction and less oxygen produced. Conclusion == I have found that by looking at my results, that as I increase the temperature, the reaction will become quicker, and more oxygen will be produced. However I have found that as the temperature rises to a certain point the catalase particles will become denatured causing the reaction to slow down. The rate of reaction increases when I increase the temperature because the more heat, the more energy is being transferred to the particles and the there is a greater chance of the catalase and the hydrogen peroxide molecules colliding with each other. As I predicted, at a certain temperature, the catalase will begin to become denatured, although I estimated 40?c, it has come earlier, at 35?c. evaluating == I felt my results were fairly accurate, as my graphs produced the results anticipated to produce, producing the shapes I predicted. However, I feel that counting bubbles is an unreliable method of measuring oxygen produced, on occasions I lost count, or may have missed bubbles that may have been crucial to results and this is how errors occurred. The bubbles going into the test tube may have been of different sizes, carrying different amounts of oxygen, therefore one big bubble could produce as much oxygen as three very small ones but yet still be counted as producing less oxygen than three others, regardless of size. The tube being placed in a different way into the test tube caused the different sized bubbles. If I were to repeat this experiment, I would try to obtain more accurate results by:
Finding a more accurate method of measuring the oxygen produced
eg, monitoring water level in the test tube.
Placing the bung into the tube very quickly as I feel some oxygen
was lost in the space of time it took to get the experiment ready
while the potato was catalysing in the hydrogen peroxide.
To further this investigation, I could look further into the different it made to the rate of the reaction if the surface area of the potato was changed, or the volume of hydrogen peroxide, I could also compare different catalase such as liver.

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