Rates Of Reaction Investigation
Biology coursework
How does the temperature affect the rate of reaction?
Introduction
For our experiments, I was investigating what affects the rate of reaction. We used Hydrogen peroxide to test the rate of reaction, with the temperature of this being our variable that we changed. Hydrogen peroxide is a clear, colourless liquid which has various amounts of uses within the laboratory, industrial purposes and even in our households. It is mainly used for cleaning products and hair dye but is also used for paper making. Hydrogen peroxide is made up of two oxygen atoms and two hydrogen atoms. The chemical formula for this is H₂O₂.
Catalyse is the enzyme that breaks down hydrogen peroxide which converts the hydrogen peroxide to hydrogen …show more content…
and water.
The chemical equation for this reaction is: 2H₂O₂ 2H₂O + O₂ The catalyse that we used is potato, and is the enzyme that I used in the experiment. This enzyme is a protein which speeds up the rate of the chemical reaction, every enzymes does this. There were various amounts of variables that we could have changed for our experiment. These variables were: to put in a catalyst, to change the surface area of the catalyse, the temperature and the concentration of the hydrogen peroxide. I also had the choice of either potato or celery. I chose to change the temperature of the hydrogen peroxide our preliminary test showed us it would be the best possible way to test the rate of reaction. This variable gave us plenty of results that were reliable as well as accurate. What can affect the rate of reaction? There are four different variables that I could have changed to lead to the rate of reaction being affected: temperature, concentration, surface area and the use of a catalyst.
Catalyst- This is a substance which alters the rate of a chemical reaction but is chemically unchanged at the end of the reaction. This means that there is just as much catalyst at the end of a reaction as there was at the beginning, and are used again and again. Because catalysts work so rapidly and are used again and again, it is only necessary to have very small quantities of catalyst present to make a chemical reaction go faster. Temperature- When you increase the temperature, the rate of reaction also increases. When this happens, two chemicals react and their molecules have to collide with each other with sufficient energy for the reaction to take place. These two molecules will only react if they have enough energy. By heating this, you will increase the energy levels of the molecules involved in the reaction. Increasing the temperature means the molecules move faster. But when the temperature gets to a certain point the reaction gets slower and eventually resulting in the reaction to stop. Surface area- If the potato we used was blended or cut into fine pieces the reaction would have occurred quickly. This example would produce a faster reaction than a large solid, with the same mass but a larger surface area. Increasing the surface area will increase the chances of collisions that will take place. Concentration- If the concentration is greater there is a higher chance that molecules will collide and speed up the rate of the reaction. If it a less concentration, there will be fewer collisions and the reaction will probably happen at a slower speed. For reactions that involve gases or liquids, when you increase the concentration of the reactant, the reaction rate also increases. When the concentration is higher, the chances of collisions are greater. Hypothesis I predict that when the temperature of the peroxide is increased,the reaction will occur a lot quicker. This will then lead to a higher volume of gas that gets produced, but if the temperature increases too much, it will cause the results to level off and then the enzyme will denature.
Equipment list * Core borer- This was used to get equal size cylinders of potato so the test would be fair. * Potatoes- We used potato because the celery caused the reaction to be too fast and the results were unreliable. * Knife- We used the knife so we could then cut the cylindrical pieces of potato in to smaller bits so the surface area was smaller. * Scales- This was used to measure each piece of potato to make it a fair test. * 100ml measuring cylinder- This was used to measure the amount of gas that was produced during the reaction * Water bath – This is where the experiment took place. * Delivery tube – one end of this was connected to the bung and the other to the measuring cylinder. This gave us accurate results for the gas collected. * Bung- This was used so the gas doesn’t escape during the reaction. * Syringe – I used this to measure equal amounts of hydrogen peroxide so they were accurate. * Hydrogen peroxide- This was the selected acid for the test. We used this at a concentration o 20% so we could get the most reliable results possible. * Stopwatch- We used a stopwatch to make sure that we timed it for 5 minutes
Safety
To ensure I, and the people around me were safe during the experiments I had to carry out some safety precautions so no one was in danger. First of all I made sure the work surface was clear of any obstacles and that any chairs were tucked under the table, out the way. I also had do make sure everyone was wearing safety goggles throughout the test encase any of the solutions were knocked and splashed up into anyone’s eyes. Everyone one participating on the experiments had to make sure their hair was tied back and any jewellery was removed. When we had to remove the measurements of hydrogen peroxide from the water bath, we needed to remove it in a way where we didn’t burn ourselves
Actual method 1. First of all, you need to select a potato for you tests and extract cylinders of potato using a core borer. These should all roughly be the same size. I did this because the cylinders are near enough 3 grams of potato that we needed. 2. Next remove the skin from each end of these cylinders so it doesn’t affect the reaction. 3. Thirdly, you need to measure out the 3 grams of potato that you need using the weighing scales. You then have to cut the potato into 9 segments, with a length if 5mm, a radius of 4mm and a diameter of 7mm so you can have complete coverage of the potato, from the hydrogen peroxide. This cancel’s out the possibility of this variable changing and making the experiment unfair. 4. Measure 25ml of hydrogen peroxide, at either 5°, 20°, 40° and 65° and put it into a conical flask. This was decided because it allows the solution to react quickly enough. 5. You then have to fill the measuring cylinder with water, and then submerge it into the water bath without any of it escaping. 6. Next you need to manoeuvre the delivery tube under the measuring cylinder in the water bath. 7. You now need to place the pieces of potato that you just cut up into the conical flask without misplacing any of them as it may lead to inaccurate results. 8. After you have placed the potato into the flask, you need to place the bung (this is on the end of the delivery tube) on the top of the flask 9. Start timing with the stopwatch straight away and record the ml decrease of gas every 30 seconds. 10. Stop timing and recording results after 5 minutes. 11. Repeat this method for each temperature, only changing step 4 for each experiment. 12. You must repeat each temperature 3 times. We did this to make our results accurate. 13. You must make sure that the potato is the same weight for each experiment to make you fair, accurate and reliable. Experiment diagram
Initial method Throughout my experiment, I will only be changing one variable for my tests, which will be the temperature of the hydrogen peroxide. The temperatures that I will use will range from 5°C, 20°C, 40°C and finally 65°C for each test. I will test the gas that is collected through the experiment every 30 seconds, for 5 minutes. I will then repeat each test 4 times to make it fair and accurate, then giving me reliable results to evaluate later on. This gives me enough data allowing me not to repeat any more of the tests. Another variable that I could have chosen to change was the surface area of the potato or the catalyst. I decided not to do this because it was too expensive and wasn’t available to me at the time. I chose not to change the surface area as felt I wouldn’t get enough results for it. It would have also been too tricky to measure as I didn’t have the right equipment to allow accurate results. I could have also changed the concentration of the hydrogen peroxide. The reason for not choosing this though was that it was a hassle trying to get the right concentration and wasted a lot of time trying to get the right concentration. Preliminary tests Preliminary test 1: Time (seconds) | 1 | 2 | 3 | 4 | 5 | 6 | Gas collected (ml) | 0 | 0 | 0 | 0 | 0 | 0 |
This was the first of the preliminary tests that I did. For this test, I used 25ml of hydrogen peroxide, at 61 degrees and 3 grams of potato. The results I got for this test weren’t very successful and I had to start thinking about what I could have changed to get a better range of results. I decided to modify this test by increasing the amount of time that I collected the results to producer a better range of results. I also decided to use a smaller, more precise measuring cylinder so I could acquire more accurate results. I then repeated each test 3 times, to remove any chance of getting outliers within the results I collected. Preliminary test 2: Time (seconds) | 10 | 20 | 30 | 40 | 50 | 60 | Gas collected (ml) | 0 | 0 | 0 | 0 | 0 | 2 |
In my second test I decided to use the same amount of hydrogen peroxide but altered the temperature of this to room temperature (27°), whilst using the same measurement of potato again (3 grams).
Once again, in order for this test to be improved, I needed to change the time I recorded the results for a better range and use a more precise measuring cylinder for the gas that gets produced. Time (seconds) | 30 | 60 | 90 | 120 | 150 | 180 | 210 | 240 | 270 | 300 | Gas collected (ml) | 0 | 4 | 5 | 7 | 8 | 9 | 10 | 10 | 12 | 13 | Preliminary test 3: For my last test, the graph shows that there was a much better range of results due to fact I increased the surface area of my potato by cutting it into small segments, which had to be of the same size, so the peroxide would completely cover it to ensure the test were fair. I had also recorded the results less often and made the tests longer. …show more content…
Justification
When I started my preliminary tests, I decided that changes were necessary before I came to do my main tests to insure that I had the most reliable and accurate results.
The first problem which I had to overcome whilst doing my preliminary was in 2 of the tests which were measured every 10 seconds for a minute, no results were recorded. To stop this happening again, I decided to change the gas collected from 10 to 30 seconds over five minutes. This change was effective in my main test as I then recorded some valid results. Another change I did for my main test was an adjustment to the surface area of the potato. Within my preliminaries I started to use 3 grams of potato but the hydrogen peroxide didn’t completely cover the potato which then caused substandard results. To correct this, I cut the potato into 9 segments with a length if 5mm, a radius of 4mm and a diameter of 7mm so I could have complete coverage of the potato from the hydrogen peroxide, which lead to more accurate results in my main tests. I had also changed the temperature of the hydrogen peroxide for my test from it being lowest at 0°, up to 5°. The reason for this is because we didn’t have the right equipment to reduce the temperature that low, so had to have it at a second choice of temperature. We did this so we could still record results for low temperatures of the hydrogen peroxide, to give us a wider range of
results. Final results
These are the result tables, with averages, showing how much gas was produced in a certain amount of time, from 4 different temperatures of hydrogen peroxide 65 Degrees (C°) | Time (seconds) | Test 1 | Test 2 | Test 3 | Test 4 | Average | 30 | 0 | 0 | 0 | 0 | 0 | 60 | 0 | 0 | 0 | 0 | 0 | 90 | 1 | 0 | 0 | 1 | 0.5 | 120 | 1 | 1 | 1 | 0 | 0.75 | 150 | 2 | 0 | 1 | 0 | 0.75 | 180 | 1 | 0 | 2 | 1 | 1 | 210 | 2 | 2 | 2 | 2 | 2 | 240 | 2 | 2 | 2 | 2 | 2 | 270 | 2 | 2 | 2 | 2 | 2 | 300 | 2 | 3 | 3 | 2 | 2.5 | 0 Degrees (C°) | Time (seconds) | Test 1 | Test 2 | Test 3 | Test 4 | Average | 30 | 0 | 0 | 0 | 0 | 0 | 60 | 0 | 0 | 1 | 0 | 0.25 | 90 | 0 | 0 | 2 | 0 | 0.5 | 120 | 0 | 0 | 3 | 0 | 0.75 | 150 | 0 | 0 | 4 | 1 | 1.25 | 180 | 0 | 0 | 4 | 1 | 1.25 | 210 | 1 | 1 | 4 | 1 | 1.75 | 240 | 1 | 1 | 5 | 1 | 2 | 270 | 1 | 1 | 6 | 2 | 2.5 | 300 | 1 | 2 | 7 | 2 | 3 |
20 Degrees (C°) | Time (seconds) | Test 1 | Test 2 | Test 3 | Test 4 | Average | 30 | 1 | 0 | 0 | 2 | 0.75 | 60 | 3 | 1 | 1 | 2 | 1.75 | 90 | 6 | 0 | 5 | 4 | 3.75 | 120 | 6 | 3 | 8 | 1 | 4.5 | 150 | 8 | 5 | 11 | 10 | 8.5 | 180 | 8 | 8 | 13 | 13 | 10.5 | 210 | 10 | 9 | 16 | 14 | 12.25 | 240 | 11 | 11 | 17 | 18 | 14.25 | 270 | 11 | 15 | 17 | 19 | 15.5 | 300 | 13 | 17 | 20 | 22 | 18 | 40 Degrees (C°) | Time (seconds) | Test 1 | Test 2 | Test 3 | Test 4 | Average | 30 | 1 | 1 | 0 | 1 | 0.75 | 60 | 2 | 3 | 3 | 2 | 2.5 | 90 | 5 | 4 | 4 | 4 | 4.25 | 120 | 8 | 7 | 7 | 7 | 7.25 | 150 | 10 | 9 | 10 | 11 | 10 | 180 | 12 | 11 | 12 | 13 | 12 | 210 | 16 | 14 | 16 | 13 | 14.75 | 240 | 16 | 15 | 17 | 15 | 15.75 | 270 | 17 | 17 | 15 | 16 | 16.25 | 300 | 19 | 18 | 22 | 18 | 19.25 | I have also made a table to show the rate of reaction using this formula: Volume of gas = rate of reaction Time 0 Degrees (C°) | Time (seconds) | Test 1 | Test 2 | Test 3 | Test 4 | Average | Rate of reaction | 30 | 0 | 0 | 0 | 0 | 0 | 0.00 | 60 | 0 | 0 | 1 | 0 | 0.25 | 0.00 | 90 | 0 | 0 | 2 | 0 | 0.5 | 0.01 | 120 | 0 | 0 | 3 | 0 | 0.75 | 0.01 | 150 | 0 | 0 | 4 | 1 | 1.25 | 0.01 | 180 | 0 | 0 | 4 | 1 | 1.25 | 0.01 | 210 | 1 | 1 | 4 | 1 | 1.75 | 0.01 | 240 | 1 | 1 | 5 | 1 | 2 | 0.01 | 270 | 1 | 1 | 6 | 2 | 2.5 | 0.01 | 300 | 1 | 2 | 7 | 2 | 3 | 0.01 |
20 Degrees (C°) | Time (seconds) | Test 1 | Test 2 | Test 3 | Test 4 | Average | Rate of reaction | 30 | 1 | 0 | 0 | 2 | 0.75 | 0.03 | 60 | 3 | 1 | 1 | 2 | 1.75 | 0.03 | 90 | 6 | 0 | 5 | 4 | 3.75 | 0.04 | 120 | 6 | 3 | 8 | 1 | 4.5 | 0.04 | 150 | 8 | 5 | 11 | 10 | 8.5 | 0.06 | 180 | 8 | 8 | 13 | 13 | 10.5 | 0.06 | 210 | 10 | 9 | 16 | 14 | 12.25 | 0.06 | 240 | 11 | 11 | 17 | 18 | 14.25 | 0.06 | 270 | 11 | 15 | 17 | 19 | 15.5 | 0.06 | 300 | 13 | 17 | 20 | 22 | 18 | 0.06 | 40 Degrees (C°) | Time (seconds) | Test 1 | Test 2 | Test 3 | Test 4 | Average | Rate of reaction | 30 | 1 | 1 | 0 | 1 | 0.75 | 0.03 | 60 | 2 | 3 | 3 | 2 | 2.5 | 0.04 | 90 | 5 | 4 | 4 | 4 | 4.25 | 0.05 | 120 | 8 | 7 | 7 | 7 | 7.25 | 0.06 | 150 | 10 | 9 | 10 | 11 | 10 | 0.07 | 180 | 12 | 11 | 12 | 13 | 12 | 0.07 | 210 | 16 | 14 | 16 | 13 | 14.75 | 0.07 | 240 | 16 | 15 | 17 | 15 | 15.75 | 0.07 | 270 | 17 | 17 | 15 | 16 | 16.25 | 0.06 | 300 | 19 | 18 | 22 | 18 | 19.25 | 0.06 |
65 Degrees (C°) | Time (seconds) | Test 1 | Test 2 | Test 3 | Test 4 | Average | Rate of reaction | 30 | 0 | 0 | 0 | 0 | 0 | 0.00 | 60 | 0 | 0 | 0 | 0 | 0 | 0.00 | 90 | 1 | 0 | 0 | 1 | 0.5 | 0.01 | 120 | 1 | 1 | 1 | 0 | 0.75 | 0.01 | 150 | 2 | 0 | 1 | 0 | 0.75 | 0.01 | 180 | 1 | 0 | 2 | 1 | 1 | 0.01 | 210 | 2 | 2 | 2 | 2 | 2 | 0.01 | 240 | 2 | 2 | 2 | 2 | 2 | 0.01 | 270 | 2 | 2 | 2 | 2 | 2 | 0.01 | 300 | 2 | 3 | 3 | 2 | 2.5 | 0.01 | Evaluation of data Overall, the data that I collected from the tests that I have done proved to be accurate and reliable. I have managed to produce some accurate graphs to show the correlation between every result. In the first graph I completed, it shows some interesting results. The temperatures 5° and 65° only show a little difference between both of them. It shows that the highest amount of gas produced from the temperatures is extremely similar, with a difference of just 0.5°. The reason for this little change in the gas that is produced is because of the extreme temperatures. Enzymes need a specific temperature present in order to be able to work at its optimum rate. At 5°, the enzyme hasn’t got enough heat in order to actually react. So, for this reason, it only produces a little amount of gas causing it to be unable to react properly. It is similar for the temperature 65°. At this temperature the enzyme is so hot; it is unable to work properly. This is then where the enzyme begins to denature. This is where the enzymes active site is damaged or has just changed shape due to the intense heat. This then means the reaction is unable to take place as the enzyme is too damaged to work. The next temperature was 5° and 40°. These temperatures were closest to the enzymes optimum temperature leading to the most gas being collected throughout the tests I did. This is because at this temperature, the enzyme has the greatest possibility to work at its 0° and 40°. These temperatures were closest to the enzymes optimum temperature leading to the most gas being collected throughout the tests I did. This is because at this temperature, the enzyme has the greatest possibility to work at its best. The temperature is high enough to speed up the reaction causing the molecules to move a lot faster and far more gas to be produced. But it isn’t too high as it would begin to denature.
Conclusion I have collected 160 separate results from my experiments. All of these results and the graphs that I have produced clearly show a positive correlation between both the temperature, and the volume of gas produced in the reaction. Both the graphs and the tables show that when the temperature is increased, it starts to produce more gas. But when the temperature gets to a certain point, the enzyme start to denature causing a sudden decrease in the gas it produces. This is what I thought would have happened, as stated in my hypothesis, so I was correct. I believe this happened because when the temperature is increased, the molecules begin to move around a lot quicker causing them to collide a lot more. This then increase the rate of the reaction. I was also right about the increased temperature denaturing the enzyme causing the reaction to stop. Evaluation There were some outliers that occurred when I was doing my tests. This was probably due to the equipment I used like the bung or weights for measuring the potato. I noticed that in some of the test, the bung didn’t exactly fit on the conical flask and the weights we used weren’t the most accurate causing these outliers. I needed to keep the test fair so I controlled the following factors: surface area, pH, concentration and temperature. I controlled the surface area of the potato by using the same core borer for each test. The concentration of the peroxide was easy to control. All I had to do was use a pipette to accurately measure the peroxide and make the concentration exact. The temperature was again easy to control as this was the variable that I was testing. All I had to do was to make sure that the water bath that I was heating the peroxide in was at the correct temperature and then completed the test as quickly and efficiently as possible. There is an obvious relationship in the data. When the temperature of the peroxide is either very low or very high, there is a significantly reduced amount of gas produced. When the temperature is at room/body temperature the reaction is at its best possible environment. You can see this if you look at both of my graphs.
How does the temperature affect the rate of reaction?
Introduction
For our experiments, I was investigating what affects the rate of reaction. We used Hydrogen peroxide to test the rate of reaction, with the temperature of this being our variable that we changed. Hydrogen peroxide is a clear, colourless liquid which has various amounts of uses within the laboratory, industrial purposes and even in our households. It is mainly used for cleaning products and hair dye but is also used for paper making. Hydrogen peroxide is made up of two oxygen atoms and two hydrogen atoms. The chemical formula for this is H₂O₂.
Catalyse is the enzyme that breaks down hydrogen peroxide which converts the hydrogen peroxide to hydrogen …show more content…
and water.
The chemical equation for this reaction is: 2H₂O₂ 2H₂O + O₂ The catalyse that we used is potato, and is the enzyme that I used in the experiment. This enzyme is a protein which speeds up the rate of the chemical reaction, every enzymes does this. There were various amounts of variables that we could have changed for our experiment. These variables were: to put in a catalyst, to change the surface area of the catalyse, the temperature and the concentration of the hydrogen peroxide. I also had the choice of either potato or celery. I chose to change the temperature of the hydrogen peroxide our preliminary test showed us it would be the best possible way to test the rate of reaction. This variable gave us plenty of results that were reliable as well as accurate. What can affect the rate of reaction? There are four different variables that I could have changed to lead to the rate of reaction being affected: temperature, concentration, surface area and the use of a catalyst.
Catalyst- This is a substance which alters the rate of a chemical reaction but is chemically unchanged at the end of the reaction. This means that there is just as much catalyst at the end of a reaction as there was at the beginning, and are used again and again. Because catalysts work so rapidly and are used again and again, it is only necessary to have very small quantities of catalyst present to make a chemical reaction go faster. Temperature- When you increase the temperature, the rate of reaction also increases. When this happens, two chemicals react and their molecules have to collide with each other with sufficient energy for the reaction to take place. These two molecules will only react if they have enough energy. By heating this, you will increase the energy levels of the molecules involved in the reaction. Increasing the temperature means the molecules move faster. But when the temperature gets to a certain point the reaction gets slower and eventually resulting in the reaction to stop. Surface area- If the potato we used was blended or cut into fine pieces the reaction would have occurred quickly. This example would produce a faster reaction than a large solid, with the same mass but a larger surface area. Increasing the surface area will increase the chances of collisions that will take place. Concentration- If the concentration is greater there is a higher chance that molecules will collide and speed up the rate of the reaction. If it a less concentration, there will be fewer collisions and the reaction will probably happen at a slower speed. For reactions that involve gases or liquids, when you increase the concentration of the reactant, the reaction rate also increases. When the concentration is higher, the chances of collisions are greater. Hypothesis I predict that when the temperature of the peroxide is increased,the reaction will occur a lot quicker. This will then lead to a higher volume of gas that gets produced, but if the temperature increases too much, it will cause the results to level off and then the enzyme will denature.
Equipment list * Core borer- This was used to get equal size cylinders of potato so the test would be fair. * Potatoes- We used potato because the celery caused the reaction to be too fast and the results were unreliable. * Knife- We used the knife so we could then cut the cylindrical pieces of potato in to smaller bits so the surface area was smaller. * Scales- This was used to measure each piece of potato to make it a fair test. * 100ml measuring cylinder- This was used to measure the amount of gas that was produced during the reaction * Water bath – This is where the experiment took place. * Delivery tube – one end of this was connected to the bung and the other to the measuring cylinder. This gave us accurate results for the gas collected. * Bung- This was used so the gas doesn’t escape during the reaction. * Syringe – I used this to measure equal amounts of hydrogen peroxide so they were accurate. * Hydrogen peroxide- This was the selected acid for the test. We used this at a concentration o 20% so we could get the most reliable results possible. * Stopwatch- We used a stopwatch to make sure that we timed it for 5 minutes
Safety
To ensure I, and the people around me were safe during the experiments I had to carry out some safety precautions so no one was in danger. First of all I made sure the work surface was clear of any obstacles and that any chairs were tucked under the table, out the way. I also had do make sure everyone was wearing safety goggles throughout the test encase any of the solutions were knocked and splashed up into anyone’s eyes. Everyone one participating on the experiments had to make sure their hair was tied back and any jewellery was removed. When we had to remove the measurements of hydrogen peroxide from the water bath, we needed to remove it in a way where we didn’t burn ourselves
Actual method 1. First of all, you need to select a potato for you tests and extract cylinders of potato using a core borer. These should all roughly be the same size. I did this because the cylinders are near enough 3 grams of potato that we needed. 2. Next remove the skin from each end of these cylinders so it doesn’t affect the reaction. 3. Thirdly, you need to measure out the 3 grams of potato that you need using the weighing scales. You then have to cut the potato into 9 segments, with a length if 5mm, a radius of 4mm and a diameter of 7mm so you can have complete coverage of the potato, from the hydrogen peroxide. This cancel’s out the possibility of this variable changing and making the experiment unfair. 4. Measure 25ml of hydrogen peroxide, at either 5°, 20°, 40° and 65° and put it into a conical flask. This was decided because it allows the solution to react quickly enough. 5. You then have to fill the measuring cylinder with water, and then submerge it into the water bath without any of it escaping. 6. Next you need to manoeuvre the delivery tube under the measuring cylinder in the water bath. 7. You now need to place the pieces of potato that you just cut up into the conical flask without misplacing any of them as it may lead to inaccurate results. 8. After you have placed the potato into the flask, you need to place the bung (this is on the end of the delivery tube) on the top of the flask 9. Start timing with the stopwatch straight away and record the ml decrease of gas every 30 seconds. 10. Stop timing and recording results after 5 minutes. 11. Repeat this method for each temperature, only changing step 4 for each experiment. 12. You must repeat each temperature 3 times. We did this to make our results accurate. 13. You must make sure that the potato is the same weight for each experiment to make you fair, accurate and reliable. Experiment diagram
Initial method Throughout my experiment, I will only be changing one variable for my tests, which will be the temperature of the hydrogen peroxide. The temperatures that I will use will range from 5°C, 20°C, 40°C and finally 65°C for each test. I will test the gas that is collected through the experiment every 30 seconds, for 5 minutes. I will then repeat each test 4 times to make it fair and accurate, then giving me reliable results to evaluate later on. This gives me enough data allowing me not to repeat any more of the tests. Another variable that I could have chosen to change was the surface area of the potato or the catalyst. I decided not to do this because it was too expensive and wasn’t available to me at the time. I chose not to change the surface area as felt I wouldn’t get enough results for it. It would have also been too tricky to measure as I didn’t have the right equipment to allow accurate results. I could have also changed the concentration of the hydrogen peroxide. The reason for not choosing this though was that it was a hassle trying to get the right concentration and wasted a lot of time trying to get the right concentration. Preliminary tests Preliminary test 1: Time (seconds) | 1 | 2 | 3 | 4 | 5 | 6 | Gas collected (ml) | 0 | 0 | 0 | 0 | 0 | 0 |
This was the first of the preliminary tests that I did. For this test, I used 25ml of hydrogen peroxide, at 61 degrees and 3 grams of potato. The results I got for this test weren’t very successful and I had to start thinking about what I could have changed to get a better range of results. I decided to modify this test by increasing the amount of time that I collected the results to producer a better range of results. I also decided to use a smaller, more precise measuring cylinder so I could acquire more accurate results. I then repeated each test 3 times, to remove any chance of getting outliers within the results I collected. Preliminary test 2: Time (seconds) | 10 | 20 | 30 | 40 | 50 | 60 | Gas collected (ml) | 0 | 0 | 0 | 0 | 0 | 2 |
In my second test I decided to use the same amount of hydrogen peroxide but altered the temperature of this to room temperature (27°), whilst using the same measurement of potato again (3 grams).
Once again, in order for this test to be improved, I needed to change the time I recorded the results for a better range and use a more precise measuring cylinder for the gas that gets produced. Time (seconds) | 30 | 60 | 90 | 120 | 150 | 180 | 210 | 240 | 270 | 300 | Gas collected (ml) | 0 | 4 | 5 | 7 | 8 | 9 | 10 | 10 | 12 | 13 | Preliminary test 3: For my last test, the graph shows that there was a much better range of results due to fact I increased the surface area of my potato by cutting it into small segments, which had to be of the same size, so the peroxide would completely cover it to ensure the test were fair. I had also recorded the results less often and made the tests longer. …show more content…
Justification
When I started my preliminary tests, I decided that changes were necessary before I came to do my main tests to insure that I had the most reliable and accurate results.
The first problem which I had to overcome whilst doing my preliminary was in 2 of the tests which were measured every 10 seconds for a minute, no results were recorded. To stop this happening again, I decided to change the gas collected from 10 to 30 seconds over five minutes. This change was effective in my main test as I then recorded some valid results. Another change I did for my main test was an adjustment to the surface area of the potato. Within my preliminaries I started to use 3 grams of potato but the hydrogen peroxide didn’t completely cover the potato which then caused substandard results. To correct this, I cut the potato into 9 segments with a length if 5mm, a radius of 4mm and a diameter of 7mm so I could have complete coverage of the potato from the hydrogen peroxide, which lead to more accurate results in my main tests. I had also changed the temperature of the hydrogen peroxide for my test from it being lowest at 0°, up to 5°. The reason for this is because we didn’t have the right equipment to reduce the temperature that low, so had to have it at a second choice of temperature. We did this so we could still record results for low temperatures of the hydrogen peroxide, to give us a wider range of
results. Final results
These are the result tables, with averages, showing how much gas was produced in a certain amount of time, from 4 different temperatures of hydrogen peroxide 65 Degrees (C°) | Time (seconds) | Test 1 | Test 2 | Test 3 | Test 4 | Average | 30 | 0 | 0 | 0 | 0 | 0 | 60 | 0 | 0 | 0 | 0 | 0 | 90 | 1 | 0 | 0 | 1 | 0.5 | 120 | 1 | 1 | 1 | 0 | 0.75 | 150 | 2 | 0 | 1 | 0 | 0.75 | 180 | 1 | 0 | 2 | 1 | 1 | 210 | 2 | 2 | 2 | 2 | 2 | 240 | 2 | 2 | 2 | 2 | 2 | 270 | 2 | 2 | 2 | 2 | 2 | 300 | 2 | 3 | 3 | 2 | 2.5 | 0 Degrees (C°) | Time (seconds) | Test 1 | Test 2 | Test 3 | Test 4 | Average | 30 | 0 | 0 | 0 | 0 | 0 | 60 | 0 | 0 | 1 | 0 | 0.25 | 90 | 0 | 0 | 2 | 0 | 0.5 | 120 | 0 | 0 | 3 | 0 | 0.75 | 150 | 0 | 0 | 4 | 1 | 1.25 | 180 | 0 | 0 | 4 | 1 | 1.25 | 210 | 1 | 1 | 4 | 1 | 1.75 | 240 | 1 | 1 | 5 | 1 | 2 | 270 | 1 | 1 | 6 | 2 | 2.5 | 300 | 1 | 2 | 7 | 2 | 3 |
20 Degrees (C°) | Time (seconds) | Test 1 | Test 2 | Test 3 | Test 4 | Average | 30 | 1 | 0 | 0 | 2 | 0.75 | 60 | 3 | 1 | 1 | 2 | 1.75 | 90 | 6 | 0 | 5 | 4 | 3.75 | 120 | 6 | 3 | 8 | 1 | 4.5 | 150 | 8 | 5 | 11 | 10 | 8.5 | 180 | 8 | 8 | 13 | 13 | 10.5 | 210 | 10 | 9 | 16 | 14 | 12.25 | 240 | 11 | 11 | 17 | 18 | 14.25 | 270 | 11 | 15 | 17 | 19 | 15.5 | 300 | 13 | 17 | 20 | 22 | 18 | 40 Degrees (C°) | Time (seconds) | Test 1 | Test 2 | Test 3 | Test 4 | Average | 30 | 1 | 1 | 0 | 1 | 0.75 | 60 | 2 | 3 | 3 | 2 | 2.5 | 90 | 5 | 4 | 4 | 4 | 4.25 | 120 | 8 | 7 | 7 | 7 | 7.25 | 150 | 10 | 9 | 10 | 11 | 10 | 180 | 12 | 11 | 12 | 13 | 12 | 210 | 16 | 14 | 16 | 13 | 14.75 | 240 | 16 | 15 | 17 | 15 | 15.75 | 270 | 17 | 17 | 15 | 16 | 16.25 | 300 | 19 | 18 | 22 | 18 | 19.25 | I have also made a table to show the rate of reaction using this formula: Volume of gas = rate of reaction Time 0 Degrees (C°) | Time (seconds) | Test 1 | Test 2 | Test 3 | Test 4 | Average | Rate of reaction | 30 | 0 | 0 | 0 | 0 | 0 | 0.00 | 60 | 0 | 0 | 1 | 0 | 0.25 | 0.00 | 90 | 0 | 0 | 2 | 0 | 0.5 | 0.01 | 120 | 0 | 0 | 3 | 0 | 0.75 | 0.01 | 150 | 0 | 0 | 4 | 1 | 1.25 | 0.01 | 180 | 0 | 0 | 4 | 1 | 1.25 | 0.01 | 210 | 1 | 1 | 4 | 1 | 1.75 | 0.01 | 240 | 1 | 1 | 5 | 1 | 2 | 0.01 | 270 | 1 | 1 | 6 | 2 | 2.5 | 0.01 | 300 | 1 | 2 | 7 | 2 | 3 | 0.01 |
20 Degrees (C°) | Time (seconds) | Test 1 | Test 2 | Test 3 | Test 4 | Average | Rate of reaction | 30 | 1 | 0 | 0 | 2 | 0.75 | 0.03 | 60 | 3 | 1 | 1 | 2 | 1.75 | 0.03 | 90 | 6 | 0 | 5 | 4 | 3.75 | 0.04 | 120 | 6 | 3 | 8 | 1 | 4.5 | 0.04 | 150 | 8 | 5 | 11 | 10 | 8.5 | 0.06 | 180 | 8 | 8 | 13 | 13 | 10.5 | 0.06 | 210 | 10 | 9 | 16 | 14 | 12.25 | 0.06 | 240 | 11 | 11 | 17 | 18 | 14.25 | 0.06 | 270 | 11 | 15 | 17 | 19 | 15.5 | 0.06 | 300 | 13 | 17 | 20 | 22 | 18 | 0.06 | 40 Degrees (C°) | Time (seconds) | Test 1 | Test 2 | Test 3 | Test 4 | Average | Rate of reaction | 30 | 1 | 1 | 0 | 1 | 0.75 | 0.03 | 60 | 2 | 3 | 3 | 2 | 2.5 | 0.04 | 90 | 5 | 4 | 4 | 4 | 4.25 | 0.05 | 120 | 8 | 7 | 7 | 7 | 7.25 | 0.06 | 150 | 10 | 9 | 10 | 11 | 10 | 0.07 | 180 | 12 | 11 | 12 | 13 | 12 | 0.07 | 210 | 16 | 14 | 16 | 13 | 14.75 | 0.07 | 240 | 16 | 15 | 17 | 15 | 15.75 | 0.07 | 270 | 17 | 17 | 15 | 16 | 16.25 | 0.06 | 300 | 19 | 18 | 22 | 18 | 19.25 | 0.06 |
65 Degrees (C°) | Time (seconds) | Test 1 | Test 2 | Test 3 | Test 4 | Average | Rate of reaction | 30 | 0 | 0 | 0 | 0 | 0 | 0.00 | 60 | 0 | 0 | 0 | 0 | 0 | 0.00 | 90 | 1 | 0 | 0 | 1 | 0.5 | 0.01 | 120 | 1 | 1 | 1 | 0 | 0.75 | 0.01 | 150 | 2 | 0 | 1 | 0 | 0.75 | 0.01 | 180 | 1 | 0 | 2 | 1 | 1 | 0.01 | 210 | 2 | 2 | 2 | 2 | 2 | 0.01 | 240 | 2 | 2 | 2 | 2 | 2 | 0.01 | 270 | 2 | 2 | 2 | 2 | 2 | 0.01 | 300 | 2 | 3 | 3 | 2 | 2.5 | 0.01 | Evaluation of data Overall, the data that I collected from the tests that I have done proved to be accurate and reliable. I have managed to produce some accurate graphs to show the correlation between every result. In the first graph I completed, it shows some interesting results. The temperatures 5° and 65° only show a little difference between both of them. It shows that the highest amount of gas produced from the temperatures is extremely similar, with a difference of just 0.5°. The reason for this little change in the gas that is produced is because of the extreme temperatures. Enzymes need a specific temperature present in order to be able to work at its optimum rate. At 5°, the enzyme hasn’t got enough heat in order to actually react. So, for this reason, it only produces a little amount of gas causing it to be unable to react properly. It is similar for the temperature 65°. At this temperature the enzyme is so hot; it is unable to work properly. This is then where the enzyme begins to denature. This is where the enzymes active site is damaged or has just changed shape due to the intense heat. This then means the reaction is unable to take place as the enzyme is too damaged to work. The next temperature was 5° and 40°. These temperatures were closest to the enzymes optimum temperature leading to the most gas being collected throughout the tests I did. This is because at this temperature, the enzyme has the greatest possibility to work at its 0° and 40°. These temperatures were closest to the enzymes optimum temperature leading to the most gas being collected throughout the tests I did. This is because at this temperature, the enzyme has the greatest possibility to work at its best. The temperature is high enough to speed up the reaction causing the molecules to move a lot faster and far more gas to be produced. But it isn’t too high as it would begin to denature.
Conclusion I have collected 160 separate results from my experiments. All of these results and the graphs that I have produced clearly show a positive correlation between both the temperature, and the volume of gas produced in the reaction. Both the graphs and the tables show that when the temperature is increased, it starts to produce more gas. But when the temperature gets to a certain point, the enzyme start to denature causing a sudden decrease in the gas it produces. This is what I thought would have happened, as stated in my hypothesis, so I was correct. I believe this happened because when the temperature is increased, the molecules begin to move around a lot quicker causing them to collide a lot more. This then increase the rate of the reaction. I was also right about the increased temperature denaturing the enzyme causing the reaction to stop. Evaluation There were some outliers that occurred when I was doing my tests. This was probably due to the equipment I used like the bung or weights for measuring the potato. I noticed that in some of the test, the bung didn’t exactly fit on the conical flask and the weights we used weren’t the most accurate causing these outliers. I needed to keep the test fair so I controlled the following factors: surface area, pH, concentration and temperature. I controlled the surface area of the potato by using the same core borer for each test. The concentration of the peroxide was easy to control. All I had to do was use a pipette to accurately measure the peroxide and make the concentration exact. The temperature was again easy to control as this was the variable that I was testing. All I had to do was to make sure that the water bath that I was heating the peroxide in was at the correct temperature and then completed the test as quickly and efficiently as possible. There is an obvious relationship in the data. When the temperature of the peroxide is either very low or very high, there is a significantly reduced amount of gas produced. When the temperature is at room/body temperature the reaction is at its best possible environment. You can see this if you look at both of my graphs.