Investigation
I will be investigating the amount of oxygen produced when the concentration of hydrogen peroxide is added to the catalase and consequently decreased. I will also be investigating the variables and factor which come into connection with the rate of the reactions. Furthermore, I shall develop my enquiry by delving into correct techniques to be used for the experiment and highlight the pieces of equipment which will be very useful to me.
Aim
My initial aim was to measure the volume of oxygen when the concentration of hydrogen peroxide is added to the enzyme (potato) and then subsequently decreased. Along with this I have many more aims which I wish to achieve they are as follows:
- To identify the factors and variables and account for them.
- To conclude whether if the equipment was adequate or needed improvements.
- To carry out a successful and accurate pre-test in order to increase my confidence and belief in my hypothesis.
- To discover a relationship with the concentration of hydrogen peroxide and the volume of oxygen produced, and then elaborate on it.
- To make a good analysis from my results to refer back to my original theory.
- To aim to conclude my coursework via an in depth conclusion and thorough evaluation to summarise all my findings and errors.
Prediction
My prediction was that the higher the concentration of hydrogen peroxide added to the enzymes, the more oxygen produced. I believe this because in this scenario there will be more H2O2 molecules rather than when the H2O2 is diluted, so it reacts more with the enzymes and consequently more of the molecules will be broken down into oxygen. I also predicted that it be would likely to have some outliers as we cannot guarantee the performance of the equipment and the variables surrounding it. I also predict that the Preliminary test will go in my favour and support my hypothesis. This will then be further supported hopefully, by the reliability of my graph.
Apparatus
For this experiment the list of apparatus goes as follows:
● Gas syringe – Used to measure the level of oxygen produced
● Hydrogen peroxide – The acid used for the experiment. Very essential
● H2O2 beaker – The container for the acid
● Potatoes – The catalyst used for the experiment. Very crucial
● Water – Used to dilute the concentration of acid
● Clamp – Used in order to hold up the gas syringe
● Knife – Used to cut the potato into equal parts
● Pipette – Used to extract the acid from its beaker (safety purposes)
● Test tube – To contain the reaction between the two (potato and acid)
● Weight scale – Used to weigh the potato to insure accuracy for the test
● Potato borer – To extract suitable sizes of the potato for the test
● Safety goggles – To guard my eyes from the harmful substances.
● Latex gloves – To protect my hands from the irritant substances.
All of the apparatus was vital for this experiment as each piece of equipment correlated with each other, regardless of how menial some of the instruments actually seem. Each had its own very important job for the experiment to work.
Safety
The safety of the experiment was a very important issue, so vital measures had to be taken. Safety goggles had to be on for the whole duration because if the acid came in to contact with the eyes, a considerable amount of damage would be done. Along with this I also decided to wear latex gloves for the experiment because of hygiene reasons and also if the acid came in contact with the skin it could be very irritant. It was also very crucial to make sure the equipment was organised because any slight slip of the hand could cause a particular instrument to fall out of place and cause damage. When using the knife whether we were carrying or cutting, we had to be really careful and passive as it could harm someone if used incorrectly.
Method
I began by implementing all the safety precautions such as clearing my area, wearing the safety equipment etc. After this I started by placing my stand and adjusting the clamp so the gas syringe was very tight and in place. Once that was set up, I began to cut my potato with a knife into small even parts which was a suitable weight that would agree with our tests. When I completed that I then poured in my H2O2 into the test tube shortly followed by the small potato parts. As soon as I done this I attached the test tube to the gas syringe so the measurements of oxygen were reliable. Because I knew that the catalysts would cause the enzymes to react as soon as they came into contact. As my experiment continued I changed the concentration of H202 with the potato to see the difference and the occurrence of the rate of reaction.
Diagram of experiment set-up
Variables
There were 3 main variables in the experiment, the independent, dependent and controlled variables. I had no control over the dependent variable which was the volume of oxygen produced as we had no idea how much the reaction would cause. The independent variable was the concentration of hydrogen peroxide. It was very essential that we changed the concentration of this repeatedly throughout the experiment; otherwise my investigation would have been extremely pointless. Finally the controlled variable was the concentration of the enzyme (potato). It was crucial to cut these pieces the same size because if cut different on one test, the rate of reaction might have been quicker or slower and in turn, ruining the whole experiment. The other variables which I aim to strictly take account for include:
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Surface Area of Potato: I will cut the pieces of potato accordingly so they are the same size for each test in order for them to be as close as possible in terms of size and so the same amount of catalase can be exposed to the hydrogen peroxide.
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Temperature: I will try to keep the temperature of the reactants equal throughout the experiment by acting the experiment at room temperature.
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Mass of Enzyme: I will attempt to keep this the same for each test by cautiously weighing the parts of the potato on precise weight scales.
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Concentration of Hydrogen Peroxide: I will keep this the same for each part of my test by gently measuring out the solution in a measuring cylinder.
Preliminary data
For my preliminary test I decided to use 4 grams of potato as I deemed this to be a suitable amount for the experiment. I poured the H202 with the potatoes and allowed the reaction to last for 2 minutes before taking down the results. I did this 5 times, however I decreased the level of H2O2 by 20% each time, apart from my last test in which I decreased it by 10%. I diluted the solution with water to make it balanced. The experiment was a success; unfortunately the level of oxygen produced by the weight of the potato was very low. It is doubtful that the weight of the enzyme caused the result to be so low. It is more likely that the gas syringe was faulty. Due to this, there was not much of a reaction.
The table shows the results and the concentrations of the acid and enzymes. Despite the low results, an evident correlation can still be made between the levels of H2O2 and enzymes corresponding to the volume of oxygen produced. As a result this still supports and strengthens my initial hypothesis.
Method Improvements
For our actual experiment we took our previous preliminary results and mistakes into consideration and we were a lot more careful this time about the accuracy of our results and also the reliability of them. We decided to input the following changes:
- Allow the reaction to last for 3 minutes rather than 2.
- Increase the weight of enzyme by 1 gram for more of a reaction.
- Perform each test 3 times for more reliable results.
- Check the gas syringe and all the other equipment is working properly.
Final Results
The table shows a clear correlation between the volume of oxygen produced and the concentration of the hydrogen peroxide. The higher the concentration of the acid, the more oxygen produced. This is exactly what I hoped for as it agrees with my hypothesis.
Analysis of the results
Looking at my graph and table, I notice a clear link between the variables (independent and dependent). There is an existing relationship between the volume of oxygen and the concentration of H2O2. Evidently, the graph shows me that the higher the concentration of H2O2, the more oxygen produced. This is also emulated in my final results table. The volume of oxygen produced at 20% H2O2 is very small compared to the substantial figure of H2O2 at 80%. Judging from the rise in oxygen produced it is very clear to me that the molecules began to create more energy and simultaneously collide into each other causing the rate of reaction to elevate. This relates back to the collision theory. This proves my original hypothesis to be correct. And I also carried out each test three times to insure the accuracy and reliability of the experiment.
Comparison
In order to gain an even better understanding of the experiment and to further insure the reliability of the experiment, I decided to compare my results to a secondary source. The source is from another group in my class who also conducted the same experiment. These are their results:
Unlike my experiment, they chose to conduct the levels of H2O2 differently. Rather than decreasing the concentration of each test by 20%, they chose to do it by 10%. However this doesn’t make a vital difference in comparison to my way because the idea is still the same. Although the concentration of enzyme is not displayed, I already know the group decided to use 5 grams of potato for each test throughout their experiment. When looking at their results it is easy to interpret the correlation between the concentration of the H2O2 and the volume of oxygen produced. Speculating the averages I can see a clear difference of oxygen produced by the acids as we go down in the table. This is very good as my results show the same correlation, so this begins to vouch for the reliability of my experiment and also strengthens my hypothesis.
Conclusion
In conclusion the experiment showed that an increase in substrate (hydrogen peroxide) will cause an increase in the rate of reaction and its products (oxygen). Simplistically meaning the more H2O2 provided, the more oxygen produced. This is excellent as it proves my intended hypothesis and prediction to be correct. From analysing my graph I can also see how this conclusion is emulated. Judging from my line of best fit, I can that as the concentration of hydrogen peroxide decreased, so did the volume of oxygen being produced. This is also mirrored by my final results table. As we decrease from 80% to 10% the same pattern is recurring. Another pondering relationship I discovered between the two concentrations was that the volume of oxygen produced by 10% was 7.2cm³, and the volume produced of oxygen produced by 80% was 15cm³. This is very interesting as 7.2cm³ multiplied by 2 is 14.4cm³. This is almost the exact figure of 80%. Therefore I can conclude, judging from my evidence, that the difference of 70% between concentrations causes a doubling effect to take shape. This means that twice the amount of reactants was being released and colliding to cause mass amounts of energy. It is very conspicuous to me that during the moment in which all these reactions were occurring, the viciousness of the hydrogen peroxide was causing the reactants to spur out of control, and cause huge amounts of collisions between the particles, which in my favour, erected more energy and increased the volume of oxygen produced. Finally, I also believe that the accuracy and reliability of my results can be shadowed by the success of my experiment not achieving any outliers or anomalies. However it doesn’t necessarily explain what the effects would be if the level of enzymes (potatoes) was higher than that of what I was using. Needless to say however, the results still prove my prediction to be correct and also mean that the general experiment was a success, despite there being some minor setbacks. Moreover I can also conclude that my results are reliable and accurate as I carried out everything correctly and also compared it with another set of results.
Evaluation
After evaluating my whole experiment and results, I believe overall I conducted it very well as well as being very successful in fulfilling my hypothesis. I used the apparatus correctly and to the best of ability. I followed the safety precautions intensely and carried out the experiment in a very concise cautious atmosphere. I acted out my method intelligently and used all the sensible and ideal techniques in order to give me the best results I could achieve. I made sure I accounted for all the variables and factors which could possibly have affected by experiment, for example temperature. Along with all this I am very proud of the collection of my results. Both the pre-test and the final test resulted in my desired outcome. I am also very confident about the actual accuracy and reliability of my experiment. From investigating my graph, I can infer that the error bars are fairly small and my averages perpetuate in a great fashion. Tandem, it’s very helpful to me knowing that the error bars do not overlap, hence I can conclude with expressing that there is a real difference between my results. Finally, to further support this reliability I also carried out a comparison of my results with another group. Although the results were different from each other, it still followed the same idea which I was adamant about. Ergo, due to all this data, I believe my experiment to have produced a great set of reliable and accurate results. However, there are quite a few ways in which I could definitely improve it if I were to repeat it again. First and foremost, I would make it my priority to check the gas syringe is working properly and has no problems with it. Secondly in order to further my understanding of the topic, I would increase the enzyme weight and possibly cut it in a different way to see if it makes a change to the rate of reaction. Also I would increase the time in which I record the reaction to see if more changes still occur even after the main spurt of acceleration of the reaction because it is likely that some reactions are still occurring, unfortunately they are likely to be invisible to the naked eye, due to their minute sizes. Nevertheless, I am still satisfied with my initial results and do not see any need for me to change my apparatus or my independent variable. Furthermore, in order to perceive a superiorly high degree of meticulousness, a severely more accurate method of measuring the surface area of the fragments of potato would have been compulsory in order to comprehend that all the surface areas were the same for each test. I strongly believe that if I had better equipment to conduct my experiment, I could have induced more accurate results. This is because my equipment wasn’t in perfect condition as they have been used extensively before. For example, the gas syringe which I made use of in my pre-test which unfortunately, turned out to be horrifically defected. The goggles also made it considerably difficult to see as there were many scratches on them which could definitely have impeded some vision; consequently this could have led to someone miss-interpreting the measurement of the liquid or the distance of a fundamental object. It is also very likely that something of this calibre could lead to an individual spilling hydrogen peroxide which would be very catastrophic and dangerous. Lastly, I defiantly believe that there should have been another way in which we could have fed the fractions of potato into the boiling tube to stop any slight risk of potential oxygen that is being produced, to be wasted and released. This was a key factor as this could have changed the whole dynamics of the experiment, and we would have been none the wiser.
