NEWS   The effect of surface area and enzyme concentration on the rate of reaction between Catalase and Hydrogen Peroxide
My Hypothesis
My hypothesis is that the substance hydrogen peroxide shall breakdown into oxygen and water in the presence of the enzyme catalase. I predict that with larger surface area therefore a greater enzyme concentration, the reaction rate will increase.
Background information
Enzymes are known to be globular proteins consisting of either a tertiary or a quaternary structure (structures containing one or more polypeptide chains which are bent and folded irreversibly). This feature provides enzymes with a range of properties. Enzymes are soluble which allows them to dissolve in water based substances making it easy to do its key role which is to breakdown molecules that are referred as substrates. Enzymes are biological catalysts that help to speed up the rate of reaction. In the human body all reactions inside the body occur with the presence of enzymes. Also another property of enzymes is that due to the tertiary structure of the enzymes they all have different irregular bending structures resulting in a variety of enzymes. In order to breakdown substances the enzyme uses a specific region known as the active site. As each enzyme has different irregular bending structures it means that they also have different active sites. For the substrates to actually be broken down by the active site it needs to have a suitable shape for it to fit into the active site in a process recognised as the ‘lock and key mechanism’.



This means that each enzyme has a specific function to breakdown specific substrates which enzymes are understood to be specific. A catalyst causes a reaction to be more likely to occur by lowering the activation energy where it does this by providing an alternative mechanism for the reaction. By lowering the activation energy it allows the reaction to reach the Transition State which is the point of maximum energy. The transition state is when a reaction will go through an in between state when bonds begin to form and at the same time old bonds are still breaking. Therefore as the catalyst allows the reaction to reach the Transition State quickly it means it increases the rate of reaction. Hydrogen peroxide is a substance containing the elements hydrogen and oxygen with the molecular formula of H2O2. This compound decomposes into oxygen (O2) and water (H2O). It is naturally found in the liver and is poisonous which it is potentially damaging to cells so it must be decomposed. The liver has the important function of making sure there are safety liquids in the body. However without anything else its decomposition is relatively slow so the decomposition needs to speed up with a specific enzyme called catalase that are located in the liver and potato skins where It is located in high concentration in a section in cells called the peroxisomes. The reaction between Catalase and Hydrogen Peroxide is known as a disproportionation reaction. This is because at the start of the reaction the Oxidation number for the Oxygen atom in the Hydrogen peroxide compound is –1. But when the Hydrogen Peroxide reacts with Catalase, water and oxygen gas produced where the Oxygen atom is both reduced and oxidised. In the water molecule oxygen gains the oxidation number –2 signifying that it has been reduced as it has gained an electron making it more negative. While for the Oxygen gas molecule, the oxidation number of Oxygen is 0 therefore signifying that it has been reduced as the oxygen atoms has gained an electron.
2H2O2 to 2H2O + O2
Oxidation number of Oxygen: -1 -2 0
This is the reaction I will be doing. Due to its function of preventing excessive H2O2 build up, the catalase allows the celluar processes that produces the hydrogen peroxide compound as a by-product to take place safely. Like all proteins and enzymes, catalase need specific surrounding conditions and factors for it to work at it’s optimum conditions which is explained below.
The key variables
1) Temperature. with greater temperature there is a greater amount of kinetic energy in the particles allowing it to cause stronger and more violent collisions, therefore making the reactants more likely to reach the transition state causing a reaction. Yet the catalyst requires the optimum condition of 37 degrees otherwise any higher will cause it to denature, where it’s time dependant when denaturing.
In my experiment I will maintain the room temperature trying to keep the reaction as a fair test where my aim is to test the effects of surface area thus the enzyme concentration. 2) pH: The pH surroundings are vital for the amino acids that make up Catalase. The pH affects the structure of the amino acids where the amino acids having it’s optimum conditions allows the Catalase to function as effective as possible where it would have it’s best structure.
In this experiment, the pH was kept constant using a pH 7 buffer solution, selected to maintain a pH level suited to the enzyme by being equal to the natural environment of the enzyme.
3) Substrate Concentration: The greater the substrate concentration the greater amount of substrate particles colliding with the other reactant therefore making the reaction more likely.
In my experiment I will sure the substrate concentration was equal. In this experiment the substrate is the Hydrogen Peroxide solution. I aim to make sure the quantity of the substrate is equal as I intend to do a fair test, by using the same volume of Hydrogen Peroxide solution.
4) Inhibition: Inhibitors are substances which decreases the activity of enzymes. They behave by disturbing the activity of the enzymes either directly or indirectly. The inhibitors limit the rate of reaction involving enzymes. There are a variety of inhibitors. Competitive inhibitors are inhibitors that compete with the substrate for the active sites of the enzyme. Non-competitive inhibitors attaches themselves to the enzyme, that alters the shape of the active site causing the substrate to be unable to occupy it where the enzyme looses it’s catalytic properties therefore meaning the enzyme is no longer able to function
No inhibitors will be added to the experiment.
5) Enzyme cofactors: They influence the functioning of enzymes where these enzyme cofactors are none protein substances. There are different types of Enzyme cofactors. One of them is the organic compound Coenzymes that influence the functioning of enzymes where although they are not permanently bonded to the enzyme, they are temporarily and loosely bonded for the duration of the reaction and then moves away once the reaction is completed. Another type of enzyme cofactors are activators which are metals that is able to bind to the active site easily. They are essential for the activation of some enzymes since they are required to allow the enzyme to bind with the substrate.
I aim not to use them in the experiment meaning they will have no effect in the rate of reaction meaning no effect on the results of the experiment, Unless enzyme cofactors are present in the potato tissue containing the Catalase.
6) Enzyme Concentration: The greater the enzyme concentration represents the greater the amount of the enzyme molecules available therefore meaning more enzymes will be able to breakdown the substrates causing a faster reaction.
In my experiment this is the main factor that will vary where the greater the surface area used in the reaction results in a greater quantity of enzyme molecules available to react with the substrate.

The reaction it catalases are crucial to our survival as the hydrogen peroxide is a potentially harmful and poisonous oxidising agent. Catalase uses the compound hydrogen peroxide to oxidise toxins in the peroxidative reaction displayed below.
H2O2 + RH2 to 2 H2O + R,
Catalase is responsible in both disproportionation and the peroxidative reactions in breaking up hydrogen peroxide. Although I’m more concerned about the disproportionation reaction, it is spectacular how catalase can aid 2 reactions in breaking down hydrogen peroxide in two reactions.
Pilot Experiment
In order to be able to perform the experiment correctly to gain desirable results I had to receive some experience in doing the experiment by doing the pilot experiment. The pilot experiment will allow me to understand which equipment of my apparatus list is needed (which I researched for). Also it will let me discover how effective the Catalase sample is and observe whether the idea of counting the amount of water being oxidised by the oxygen decomposed from the hydrogen peroxide is a suitable method for measuring the rate at which oxygen is secreted varying from the surface area used. Also it will let me discover whether the time limit that I want to use is appropriate and sufficient. I will do a fair experiment with all other factors having the same quantity except for the enzyme concentration.
Outline method
To add pH7 buffer solution, catalase sample and hydrogen peroxide together and to observe the rate of reaction by analysing how quickly oxygen is released from the hydrogen peroxide’s decomposition. In order to have the opportunity of analysing how much and how fast the oxygen is being produced from the decomposition, I have setted up an apparatus with a gas pipe going through an icecream box full of water into a burette containing water. It eliminates the water that I will place in a burette while being timed. The reactants in the test tube will not be shaked where I want to observe Catalase effects naturally.

Risk Assessment
Catalase
The catalase is a type of enzyme that are dangerous so it’s necessary to wear gloves and a lab coat and use forceps to protect the skin. Also wear goggles to protect the eyes. Although in this experiment the catalase are in the samples.
Hydrogen Peroxide
Corrosive Information
Any type of solution that has a stronger molar strength or equal strength to 5.9 M are referred as corrosive substances and are capable of causing burns. The molar strength of solutions to be an irritant to the skin and eyes has to be around 5.9 M to 1.5 M.
Menacing with:
- Organic compounds including the alcohol ethanol, the ketone propanone, the lipid glycerol and a range of others.
- Metal and metal oxides that tend to cause violent decomposition of Hydrogen Peroxide. This is especially true if the metal oxide or metal is finely divided. Tin Chloride also has a negative effect when reacting with Hydrogen Peroxide.
The Hydrogen Peroxide substance must be kept away from the mouth and must never be egested. If it is swallowed it may prove to be fatal. It causes serious internal damage due to the release of oxygen.
General Information of the usage of Hydrogen Peroxide
Whenever using the Hydrogen Peroxide substance, there must be eye protection (goggles) to prevent any spillage of the substance from reaching the eyes. Also it is advisable that gloves are worn when using Hydrogen Peroxide.
Oxygen
Oxidising Agent
This is indefinitely a risk on large scale even if a gas cylinder leak happens.
Menacing with:
-Concentrated Ammonia solution that may result in explosions occurring.
-Combustible materials where they will burn more ferocious in atmosphere surrounding consisting of the oxygen gas.
Equipment for Pilot Test
-Potato
-Chopping board
-20 Test tubes
-100 cm3 of Hydrogen Peroxide (total)
-Tongs or most preferable: pair of disposable forceps
-Test tube rack
-Ice cream box
-Beaker for hydrogen peroxide
-Water
-20 Labels and a marker pen
-Gas delivery tube
-Cork borers (a range of them)
-Petri dish
-Razor blade
-Stop clock
-Graduated pipette (small version)
-Burette
-pH7 buffer solution
-Ruler
-Safety pipette filler
-Manometer (backup apparatus)
-Laboratory coat
-Gloves
-Goggles
Results
Hydrogen Peroxide and Potato Catalyst Reactions Tables
The cork borer used for the experiments used with Potato sample was the cork borer sized 4
Time Amount of water oxidised (cm3) Water volume
00:00 0 47 cm3
00:30 0 47 cm3
01:00 0.6 46.4 cm3
01:30 2.1 44.9 cm3
02:00 2.6 44.4 cm3
02:30 3.4 43.6 cm3
03:00 4.4 42.6 cm3
03:30 5.6 41.4 cm3
04:00 6.5 40.5 cm3

Time Amount of water oxidised (cm3) Water volume
00:00 0 36.4 cm3
00:30 0 36.4 cm3
01:00 0.4 36 cm3
01:30 0.8 35.6 cm3
02:00 2 34.4 cm3
02:30 3.2 33.2 cm3
03:00 3.9 32.5 cm3
03:30 5.8 30.6 cm3
04:00 6.9 29.5 cm3

Time Amount of Water Broken down (cm3) Water volume
00:00 0 46.4 cm3
00:30 2 44.4 cm3
01:00 2.2 44.2 cm3
01:30 3.1 43.3 cm3
02:00 3.9 42.5 cm3
02:30 4.8 41.6 cm3
03:00 5.4 41 cm3
03:30 5.9 40.5 cm3
04:00 6.4 40 cm3

Time Amount of water oxidised (cm3) Water volume
00:00 0 48 cm3
00:30 0 48 cm3
01:00 0 48 cm3
01:30 0.6 47.4 cm3
02:00 1 47 cm3
02:30 1.3 46.7 cm3
03:00 1.6 46.4 cm3
03:30 2 46 cm3
04:00 2.5 45.5 cm3
Hydrogen Peroxide and Liver Catalyst Reactions Tables
Time Amount of water oxidised (cm3) Water volume
00:00 0 46.4 cm3
00:30 8.4 38 cm3
01:00 20.4 26 cm3
01:30 40.4 6 cm3
02:00 46.4 (finished at 1:43.46)
02:30 46.4
03:00 46.4
03:30 46.4
04:00 46.4
The cork borer used for this experiment was size 10
Time Amount of water oxidised (cm3) Water volume
00:00 0 47.4 cm3
00:30 1.4 46 cm3
01:00 1.7 45.7 cm3
01:30 5.6 41.8 cm3
02:00 7.2 40.2 cm3
02:30 8.9 38.5 cm3
03:00 10.4 37 cm3
03:30 12.2 35.2 cm3
04:00 13.8 33.6 cm3
The cork borer used for this experiment was size 6.
Conclusion for the Pilot test
The Catalase within the potato sample that was used were extremely weak and was unable to cause a fast reaction with the hydrogen peroxide meaning the oxygen was being decomposed very slowly causing a lot of the water to remain in the burette. This isn’t good as my aim of the experiment is to analyse how fast the water is oxidised by the oxygen gas that is produced from the reaction as this will indicate the rate of reaction. I want to analyse the different effects of different surface areas with the usage of different cork borers and see the effect they have on making the Catalase speed up the reaction of the Hydrogen Peroxide’s decomposition. Yet fortunately there was also some chicken liver available during the pilot experiment which is another source of Catalase. I also used the chicken liver during the pilot where it gave me a much better set of results for the pilot as I have presented in the result section. Therefore I was forced to change the catalase sample for my final experiment from potato to liver (chicken liver). I also had learnt to saturate the water with the presence of a gas cylinder.
Equipment of real practical
-Gas delivery tube
-Chopping board
-20 Test tubes with bung
-100 ml of Hydrogen Peroxide
-Pair of disposable forceps
-Test tube rack
-Ice cream box
-Two 500ml beakers where one will be used to contain the Hydrogen Peroxide
-Water
-A range of cork borers
-Chicken liver
-Marker pen
-Rubber tubing
-Stop clock
-2 Graduated pipettes (10 cm3)
-Safety pipette filler
-Ruler
-pH7 buffer solution
-Burette and Burette holder
-Stand
-Lab coat
-Plastic gloves
-Goggles
-Gas cylinder
Diagram of Apparatus









Method for the actual experiment
1) Gather all the equipment from the tray presented to me consisting of all the equipment requested for in my apparatus list.
2) Begin preparing to have the equipment ready for the experiment like the diagram shows except for the equipment that needs something to be done to it.
3)I will firstly get the test tube which will contain the reactants ready by placing the test tube into the test tube rack. (make sure for each experiment that a new test tube is used to make the results fair)
4) Next fill the ice cream box with a reasonable volume of water
5) Then by using the gas cylinder, add the oxygen into the water within the ice cream box for about five minutes. for reasons stated in the risk assessment about the gas cylinder, everyone must act in caution when near the gas chamber as consumption of the oxygen can be fatal.(as its poisonous b careful, must add in risk assessment) 3 enters in between each step
6) After fill the burette with water. The burette is too big to be able to put it onto a sink and fill it up with only tap water so that’s is why I have asked for another beaker so I can use it to fill the burette. Also trying to put the burette into the sink and trying to make the tap water by itself to fill the burette may result in breaking the equipment. Make sure u don’t fill it completely as you don’t want too much water in it as you want a sufficient amount in order for the water volume to be within the measuring section. This will allow myself to measure the water being volume during the reaction accurately without any flaws.
7) Then without spilling the water, carefully put it into the water within the ice cream box (so no water will escape) with some space from the bottom and attach the burette to the burette holder, which is attached to the stand. Make sure that all these equipment are strongly attached to each other.
8) Then using the chopping board that I have placed at its required location as stated in step 2, I will transport some of the chicken liver (the Catalase sample) onto the chopping board.
9) Next I will get the specific sized cork borer that I intend to use for the experiment (obviously varying per experiment) and remove a bit of the chicken liver from the sample.
10) Afterwards I will then use the disposable forceps to transport the piece of chicken liver (that I removed with the use of cork borer) into the test tube that I will use for the experiment.
11) Then I will remove the air in the pipette filler, then put it on top of one of the graduated pipettes and use it to suck up 10 cm3 of the pH7 buffer solution that has already been prepared for me, and put it into the test tube containing the chicken liver piece.
12) The experiment is nearly ready to begin so it’s a good time do get the gas delivery tube ready. By putting the gas delivery tube’s ending into the ice cream box consisting water and make sure its inside the burette so when oxygen is released during the experiment it will be released from the gas delivery tube into the burette. The reason why I didn’t do this immediately was because I don’t want to clog the gas delivery tube with excess water.
13) After I will get the other graduated pipettes and after again removing the air from the pipette filler by pressing the button labelled with the number 1and attaching it to this graduated pipette, I will suck up 10 cm3 of Hydrogen Peroxide from 1 of the beakers (this is a limitation as when its in a beaker, it can decompose while in the bottle cap, it is less likely to decompose) and then place it into the test tube. As I do this, I have to place the rubber stopper from the gas delivery tube onto the top of the test tube to ensure that the oxygen only travels inside the delivery tube into the burette.
14) As the experiment will take place I will analyse the experiment and note down the water volume in the burette every 30 seconds.
15) Once the experiment is over and I have wrote down the results, I will repeat these steps and repeat the experiment again with the same or different cork borer depending if I have used that cork borer twice already.
Results
Tables
Cork borer size: 10
Time Amount of water oxidised (cm3) Water volume
00:00 0 49.2 cm3
00:30 5.7 43.5 cm3
01:00 17.4 31.8 cm3
01:30 31.8 17.4 cm3
02:00 48 1.2 cm3
02:30 49.2 0 cm3
03:00 49.2 0 cm3
03:30 49.2 0 cm3
04:00 49.2 0 cm3
The above table shows the results of the reaction using cork borer 10.
Time Amount of water oxidised (cm3) Water volume
00:00 0 47.5 cm3
00:30 4.9 42.6 cm3
01:00 17.1 30.4 cm3
01:30 35 17.5 cm3
02:00 45.5 2 cm3
02:30 47.5 0 cm3
03:00 47.5 0 cm3
03:30 47.5 0 cm3
04:00 47.5 0 cm3
The above table shows the results of the reaction when I repeated using cork borer 10.
Cork borer: 9
Time Amount of water oxidised (cm3) Water volume
00:00 0 47.7 cm3
00:30 0.7 47 cm3
01:00 6.3 41.4 cm3
01:30 12.7 35 cm3
02:00 24.5 23.2 cm3
02:30 35.9 11.8 cm3
03:00 44.6 3.1 cm3
03:30 47.7 0 cm3
04:00 47.7 0 cm3
The above table shows the results of the reaction using cork borer 9.
Time Amount of water oxidised (cm3) Water volume
00:00 0 47.6 cm3
00:30 3.6 44 cm3
01:00 8.9 38.7 cm3
01:30 15.1 32.5 cm3
02:00 24.6 23 cm3
02:30 35.1 12.5 cm3
03:00 43.7 3.9 cm3
03:30 47.6 0 cm3
04:00 47.6 0 cm3
The above table shows the results of the reaction when I repeated using cork borer 9.
Cork Borer size: 8
Time Amount of water oxidised (cm3) Water volume
00:00 0 47.6 cm3
00:30 0.6 47 cm3
01:00 4.4 43.2 cm3
01:30 9.6 38 cm3
02:00 12.4 32.5 cm3
02:30 19.8 27.8 cm3
03:00 23.6 24 cm3
03:30 28.4 19.2 cm3
04:00 32.1 15.5 cm3
The above table shows the results of the reaction using cork borer 8.
Time Amount of water oxidised (cm3) Water volume
00:00 0 46 cm3
00:30 1.2 44.8 cm3
01:00 6.8 39.2 cm3
01:30 11.5 34.5 cm3
02:00 17.6 28.4 cm3
02:30 21.2 24.8 cm3
03:00 26.3 19.7 cm3
03:30 31.4 14.6 cm3
04:00 35.5 10.5 cm3
The above table shows the results of the reaction when I repeated using cork borer 8.
Cork Borer size: 6
Time Amount of water oxidised (cm3) Water volume
00:00 0 48.8 cm3
00:30 1.6 47.2 cm3
01:00 6.7 42.1 cm3
01:30 12.4 36.4 cm3
02:00 16.1 32.7 cm3
02:30 20.7 28.1 cm3
03:00 24.6 24.2 cm3
03:30 30.2 18.6 cm3
04:00 34.2 14.6 cm3
The above table shows the results of the reaction using cork borer 6.
Time Amount of water oxidised (cm3) Water volume
00:00 0 48 cm3
00:30 1 47 cm3
01:00 5.8 42.2 cm3
01:30 10.4 37.6 cm3
02:00 13.8 34.2 cm3
02:30 18.4 29.6 cm3
03:00 23.2 24.8 cm3
03:30 28 20 cm3
04:00 33 15 cm3
The above table shows the results of the reaction when I repeated using cork borer 6.
Cork Borer size: 3
Time Amount of water oxidised (cm3) Water volume
00:00 0 49.1 cm3
00:30 0 49.1 cm3
01:00 1.7 47.4 cm3
01:30 4.3 44.8 cm3
02:00 6.9 42.2 cm3
02:30 9.4 39.7 cm3
03:00 12 37.1 cm3
03:30 14.5 34.6 cm3
04:00 17.1 32 cm3
The above table shows the results of the reaction using cork borer 3.
Time Amount of water oxidised (cm3) Water volume
00:00 0 48.6 cm3
00:30 0 48.6 cm3
01:00 1.6 47 cm3
01:30 3.8 44.8 cm3
02:00 6.1 42.5 cm3
02:30 9 39.6 cm3
03:00 11.3 37.3 cm3
03:30 13.6 35 cm3
04:00 15.2 33.4 cm3
The above table shows the results of the reaction when I repeated using cork borer 3.
Cork Borer size: 2
Time Amount of water oxidised (cm3) Water volume
00:00 0 48.2 cm3
00:30 0 48.2 cm3
01:00 1 47.2 cm3
01:30 1.8 46.4 cm3
02:00 2.3 45.9 cm3
02:30 3.6 44.6 cm3
03:00 4.4 43.8 cm3
03:30 5.5 42.7 cm3
04:00 6.6 41.6 cm3
The above table shows the results of the reaction using cork borer 2.
Time Amount of water oxidised (cm3) Water volume
00:00 0 48.5 cm3
00:30 0 48.5 cm3
01:00 0.7 47.8 cm3
01:30 2 46.5 cm3
02:00 2.8 45.7 cm3
02:30 3.6 44.9 cm3
03:00 5 43.5 cm3
03:30 5.7 42.8 cm3
04:00 6.5 42 cm3
The above table shows the results of the reaction when I repeated using cork borer 2.
Analysis
By analysing the set of results that I have gained in my experiment of Hydrogen Peroxide reacting with the liver Catalase, I have noticed a specific trend. I have recognised that the reactions that used the larger sized cork borers tend to have a greater rate of reaction than the smaller sized cork borers. The larger cork borers provided a larger surface area for the liver sample and the smaller cork borers provided the smaller surface areas. The largest sized cork borer was sized 10, which provided the liver Catalase sample to have a diameter of 1.7cm. The second largest sized cork borer was sized 9, which provided the liver Catalase sample to have a diameter of 1.4 cm. The third largest sized cork borer was sized 8, which provided the liver Catalase sample to have a diameter of 1.2 cm. The third smallest sized cork borer was sized 6, which provided the liver Catalase sample to have a diameter of 1.1 cm. The second smallest sized cork borer was sized 3, which provided the liver Catalase sample to have a diameter of 0.6 cm. The smallest sized cork borer was sized 2, which provided the liver Catalase sample to have a diameter of 0.45 cm.
I believe that the result table and the result graphs of the reaction using the cork borer size 10 had the fastest reaction rate. I believe this because the water was oxidised extremely quickly. The volume content of the water in the 1st reaction constantly was going down rapidly where the amount of water being oxidised was increasing every 30 seconds. For the 1st 30 seconds the amount of water oxidised was 5.7 cm3. Then for the time limit between 30 seconds and the 1st minute there was more water oxidised which the amount oxidised increased to 11.7 cm3 amount of water during that period. Next for the time limit between 1st minute and 1:30 minutes witnessed more water being oxidised but at an even greater rate of 14.4 cm3. After the time limit between 1:30 minutes and 2 minutes observed even more water being oxidised at the highest rate of the reaction which was 16.2 cm3. The remaining amount of water at the 2 minutes to 2:30 minutes part of the reaction (1.2 cm3) was very small which got oxidised very quickly. The repeated experiment using the same cork borer size had a similar pattern of results of an increasing amount of water oxidising at each time sector from 4.9 cm3 to 12.2 cm3 to 12.9 cm3 finally to 15.5cm3 where the last time sector only had a small amount of water (2 cm3) that was available to get oxidised. Therefore both set of results express a specific trend that as the time increased, the rate of reaction of the experiment was rising resulting in more water being oxidised at each time sector. Also the reaction finished well before the last time sector (3:30-4 minutes).
I believe that the result table and the result graphs of the reaction using the cork borer size 9 had the second fastest reaction rate. I believe this because the water was oxidised very quickly. The volume content of the water in the 1st reaction was going down swiftly where the amount of water being oxidised was high every 30 seconds. For the 1st 30 seconds the amount of water oxidised was. Then for the time limit between 30 seconds and the 1st minute there was more water oxidised which the amount oxidised increased to 5.6 cm3 amount of water during that period. Next for the time limit between 1st minute and 1:30 minutes witnessed more water being oxidised but at an even greater rate of 6.4 cm3. After the time limit between 1:30 minutes and 2 minutes observed a lot of water being oxidised of 11.8 cm3, which was at it’s highest rate. Then for the 2 minutes and 2:30 minutes a similar effect as the previous time sector reaction of 11.2 cm3 which didn’t have a greater rate of reaction therefore expressing that the optimum rate of the reaction had been reached. Then for the time limit between 2:30 minutes and 3 minutes the amount of water oxidised decreased to 8.7 cm3 which suggests that the rate of reaction has decreased. The next time limit which was the final sector for this experiment (3 to 3:30 minutes) only had 3.1 cm3 amount of water remaining to oxidise which was oxidised before the next time limit. The repeated experiment using the same cork borer size had a similar pattern of results of an increasing amount of water oxidising at each time sector from 3.6 cm3 to 5.3 cm3 to 6.2 cm3 to 9.5 cm3 to 10.5 cm3 finally to 8.6 cm3 where the last time sector only had a small amount of water (3.9cm3) that was available to get oxidised. Therefore both set of results express a specific trend that the experiment’s rate of reaction kept on increasing until it reached the time limit between 2 minutes to 3 minutes where the rate of reaction then therefore began to decrease. It also indicates it takes a while in order for the enzyme to reach it’s maximum rate.
I believe that the result table and the result graphs of the reaction using the cork borer size 8 had the third fastest reaction rate. I believe this because the water was oxidised quite quickly. The volume content of the water in the 1st reaction was going down a bit fast where the amount of water being oxidised was sufficiently high every 30 seconds. For the 1st 30 seconds the amount of water oxidised was 0.6 cm3. Then for the time limit between 30 seconds and the 1st minute there was more water oxidised which the amount oxidised increased to 3.8 cm3 amount of water during that period. Next for the time limit between 1st minute and 1:30 minutes witnessed more water being oxidised at the rate of 5.2 cm3 which was a huge increase. After the time limit between 1:30 minutes and 2 minutes even a greater rate of water was oxidised of 5.5 cm3 which was at it’s highest rate. Then for the time limit between 2 minutes and 2:30 minutes observed a similar effect as the previous time sector reaction yet weaker of 4.7 cm3 which didn’t have a greater rate of reaction therefore expressing that the optimum rate of the reaction had been reached. After for the time limit of 2:30 minutes to 3 minutes the amount of water oxidised decreased to 3.8 cm3 which suggests that the rate of reaction has decreased. Then for the time limit of 3 to 3:30 minutes the amount of water oxidised increased to 4.8 cm3, however wasn’t as high as the 5.5 cm3 of a previous time limit meaning they were still not near the optimum level meaning this time limit wasn’t a significant increase. The next time limit was the final sector for the time limit I wanted to use for my experiment, which the amount of water oxidised decreased back to 3.8 cm3. The repeated experiment using the same cork borer size had a similar pattern of results of an increasing amount of water oxidising at each time sector from 1.2 cm3 to 5.6 cm3 to 4.7 cm3 to 6.1 cm3 to 3.6 cm3 to 5.1 cm3 to 5.1 cm3 then finally to 4.1 cm3. Therefore both set of results express a specific trend that the experiment’s rate of reaction reached its optimum very quickly then started oxidising water at similar rates afterwards.
I believe that the result table and the result graphs of the reaction using the cork borer size 6 had the third slowest reaction rate. I believe this because the water was oxidised quite slowly. The volume content of the water in the 1st reaction was going down a bit slow where the amount of water being oxidised was sufficient every 30 seconds. For the 1st 30 seconds the amount of water oxidised was 1.6 cm3. Then for the time limit between 30 seconds and the 1st minute there was more water oxidised which the amount oxidised increased to 5.1 cm3 amount of water during that period. Next for the time limit between 1st minute and 1:30 minutes witnessed more water being oxidised at the rate of 5.7 cm3 which was at it’s highest rate. After the time limit between 1:30 minutes and 2 minutes the rate of reaction went down by a lot as the amount of water oxidised during that time limit went down to 3.7 cm3 therefore expressing that the optimum rate of the reaction had been reached. Then for the time limit between 2 minutes and 2:30 minutes observed a general increase in the rate of reaction causing 4.6 cm3 of water to be oxidised. After for the time limit of 2:30 minutes to 3 minutes the amount of water oxidised decreased to 3.9 cm3 which suggests that the rate of reaction has decreased again. Then for the time limit of 3 to 3:30 minutes the amount of water oxidised significantly increased to 5.6 cm3, however wasn’t as high as the 5.7 cm3 of a previous time limit meaning that it wasn’t on the same rate as the rate of reaction when the experiment experienced it’s optimum level when oxidising 5.7 cm3 of water. The next time limit was the final sector for the time limit I wanted to use for my experiment, which the amount of water oxidised decreased back to 4 cm3. The repeated experiment using the same cork borer size had a similar pattern of results of an increasing amount of water oxidising at each time sector from 1 cm3 to 4.8 cm3 to 4.6 cm3 to 3.4 cm3 to 4.6 cm3 to 4.8 cm3 to 4.8 cm3 then finally to 5 cm3. Therefore both set of results express a specific trend that the experiment’s rate of reaction tends to be similar throughout the reaction where it oxidise similar amounts throughout the experiment although it didn’t oxidise a lot. The results were surprisingly similar to the cork borer size 8 reactions.
I believe that the result table and the result graphs of the reaction using the cork borer size 3 had the second slowest reaction rate. I believe this because the water was oxidised slowly. The volume content of the water in the 1st reaction was going down slow where the amount of water being oxidised was insufficient every 30 seconds. For the 1st 30 seconds the amount of water oxidised was 0 cm3 which isn’t good. Then for the time limit between 30 seconds and the 1st minute there was more water oxidised which the amount oxidised increased to 1.7 cm3 amount of water during that period. Next for the time limit between 1st minute and 1:30 minutes witnessed more water being oxidised at the rate of 2.6 cm3 which was at it’s highest rate. After the time limit between 1:30 minutes and 2 minutes the rate of reaction remained meaning the amount of water oxidised was 2.6 cm3 therefore expressing that the experiment was still at it’s optimum rate of the reaction. Then for the time limit between 2 minutes and 2:30 minutes observed a slight decrease in the rate of reaction causing 2.5 cm3 of water to be oxidised. After for the time limit of 2:30 minutes to 3 minutes the amount of water oxidised returned to it’s optimum rate meaning the amount oxidised was 2.6 cm3. Then for the time limit of 3 to 3:30 minutes the amount of water oxidised decreased back to 2.5 cm3. The next time limit was the final sector for the time limit I wanted to use for my experiment, which the amount of water oxidised increased back to it’s optimum rate of 2.6 cm3 of water being oxidised. The repeated experiment using the same cork borer size had a similar pattern of results of an increasing amount of water oxidising at each time sector from 0 cm3 to 1.6 cm3 to 2.2 cm3 to 2.3 cm3 to 2.9 cm3 to 2.3 cm3 to 2.3 cm3 then finally to 1.6 cm3. Therefore both set of results express a specific trend that the experiment’s rate of reaction tends to be similar throughout the reaction where it oxidise similar amounts throughout the experiment where it’s usually near/ or at it’s optimum rate.
I believe that the result table and the result graphs of the reaction using the cork borer size 2 had the slowest reaction rate. I believe this because the water was oxidised very slowly. The volume content of the water in the 1st reaction was going down slow where the amount of water being oxidised was insufficient every 30 seconds. For the 1st 30 seconds the amount of water oxidised was 0 cm3, which isn’t good. Then for the time limit between 30 seconds and the 1st minute there was more water oxidised which the amount oxidised increased to 1 cm3 amount of water during that period. Next for the time limit between 1st minute and 1:30 minutes witnessed a lower amount of water being oxidised at the rate of 0.8 cm3 which was at it’s highest rate. After the time limit between 1:30 minutes and 2 minutes the rate of reaction decreased even more where the amount of water oxidised was 0.5 cm3. Then for the time limit between 2 minutes and 2:30 minutes observed a huge increase in the rate of reaction causing 1.3 cm3 of water to be oxidised where this was it’s optimum rate. After for the time limit of 2:30 minutes to 3 minutes the amount of water oxidised decreased again to 0.8 cm3. Then for the time limit of 3 to 3:30 minutes the amount of water oxidised increased a lot to 1.1 cm3. The next time limit was the final sector for the time limit I wanted to use for my experiment, which the amount of water oxidised remained at the previous amount of 1.1 cm3 of water being oxidised. The repeated experiment using the same cork borer size had a similar pattern of results of an increasing amount of water oxidising at each time sector from 0 cm3 to 0.7 cm3 to 1.3 cm3 to 0.8 cm3 to 0.8 cm3 to 1.4 cm3 to 0.7 cm3 then finally to 0.8 cm3. Therefore both set of results express a specific trend that the experiment’s rate of reaction tends to be similar throughout the reaction where it oxidise similar amounts throughout the experiment where it’s usually near/ or at it’s optimum rate.
Explanation of the Results
I strongly believe that these results provide strong evidence for one of the factors of the collision theory and also backups my hypothesis where the surface area was a major influence in my experiment. Where the collision theory states that the greater the surface area, the greater abundance of the solid’s particle available at it’s surface for collision with the solution’s particles therefore increasing the rate of reaction. The only particles that react with solutions are it’s surface particles due to the structure of solids where the atoms/molecules are strongly joined together preventing any solution from going through it. This was certainly reflected in my results. An important fact is that I used the same liver piece when extracting a liver Catalase sample meaning there was no size variance in all the catalyst samples beside from their surface area. In my experiment using the size 10 cork borer, it gave the liver Catalase sample the highest surface area out of all my experiments meaning it possessed the highest amount of liver particles available at it’s surface. This therefore caused more liver particles to collide with the hydrogen peroxide solution. This resulted in more oxygen gas being produced which oxidised the water, where as more oxygen was being produced it caused the entire water sample to be oxidised quickly. In contrast in my experiment using the size 2 cork borer, it provided the liver sample the lowest surface area out of all my experiments meaning it possessed the lowest amount of liver particles available at it’s surface. This therefore caused less liver particles to collide with the hydrogen peroxide solution. This resulted in less oxygen gas being produced that oxidised the water, where as a less oxygen gas was being produced a low amount of water was oxidised during the time limit of the experiment. The surface area was a major influence of the rate of reaction therefore producing the trends that I obtained. Since the solid being used was an enzyme it means the greater surface area causes greater amount of enzymes. As the hydrogen peroxide quantity doesn’t change in my experiment the substrate concentration value remains the same in all my experiment. Therefore the ‘turn over rate’ value for each enzyme doesn’t change. However increasing the concentration of enzymes which my experiment intends to do, causes more enzymes to breakdown the substrate at the same time meaning there are more enzymes performing the ‘turn over rate’ which therefore increases the rate of reaction.
Another explanation that I believe is the greater surface area of catalyst causes lower amount of activation energy being used up making the reaction begin time earlier. This means the greater the surface area the quicker the reaction reaches the Transition State quicker.

Evaluation
I believe that I have been able to do a successful experiment to gain suitable results for my project. However I believe that there are many activities that I can do which could provide me with a greater and better understanding about the catalase enzyme and it’s interactions with the hydrogen peroxide. From my coursework I have learnt that the greater the surface area of the solid substance where in this case the catalase, the greater the rate of reaction. Also with the less surface area of the enzyme catalase, the lower the rate of reaction. But from my research at the start of this coursework about the key variables, I learnt that there are other factors that also effect the rate of reaction of the decomposition of H2O2 with the assistance of catalase. These other factors were the temperature of the surroundings (system), the pH conditions of the surroundings (system), the substrate concentration where in this case this is the particles of the hydrogen peroxide solution, inhibition where this could be any solution which has an effect on the enzyme’s (catalase) ability to react in it’s optimum rate and the enzyme cofactors. Just like the surface area, these other factors also has a crucial relevance to the rate of any enzyme reaction. Along with the surface area, the factors of temperature and concentration of the reactants are other factors stated in the collision theory (along with catalyst) of being factors affecting the rate of the reaction. They have an effect on the collisions of the particles of the reactants similar to the surface area. The collision theory states that the greater the amount of each of these factors, the greater the rate of the reaction. But according to the key variables information this is only limited for the temperature factor. Temperature can be seen as a very efficient factor due to the kinetic theory. Yet all reactions within the human body occur with the presence of an enzyme. As stated in the background information and the key variables the average value is the body temperature of 37 degrees where a greater value than this may cause the enzyme to denature. Which they’re time dependent where greater time of exposure causes a greater denaturing effect. The pH conditions also has a similar effect indeed which it’s value is also vital for the enzyme. According to my background research and key variables information the pH optimum for Catalase is pH7 which is normal (neutral) conditions allows the Catalase to be at it’s most stable form since they are ideal for the amine and carboxylic groups of the amino acid. However if the pH surrounding value changes it would affect these groups which will cause the shape of the amino acids to change making the Catalase less efficient. With this information I would like to test out their effects as well on the rate of reaction and analyse the trends caused by each of these factors. I would like to use different temperatures with the use of ice, a Bunsen burner and several other temperature conditions to test out the effects of temperature on the rate of reaction between Catalase and Hydrogen Peroxide (the disproportionation reaction. I would use different pH buffer solutions which provides different pH surrounding conditions therefore allows me to test out the effects of temperature on the rate of reaction between Catalase and Hydrogen Peroxide (the disproportionation reaction).
Also I believe that although I had gained accurate results displaying the ideal trends about the effect of surface area on solids in the rate of reaction, I think that I should of done two repeats instead of a single repeat for each cork borer size. This would of provided greater support for the results that I achieved for each cork borer size if they were similar to each other like how my original and repeated experiments are for each cork borer size.
With the idea of performing more repeats in mind, I also assume that it would be a reasonable concept to use a greater variety of cork borer sizes. I have shown that the greater the surface area the greater the rate of reaction, yet I’m curious about the limit of when this fact is no longer true. Since my experiment consisted of the factors of enzyme concentration and the surface area of the enzyme, I want to focus on a greater variety of concentrations of enzymes. Remember that the concentration of Hydrogen Peroxide (the substrate) is always the same, meaning at each experiment there is a specific concentration of Hydrogen Peroxide. I want to discover the maximum surface area of an enzyme that can be used which will react at the maximum rate of reaction due to the limited amount of substrate molecules. I also want to discover the minimum surface area that can be used which will react at the minimum rate of reaction. For the attempts of trying to find the maximum surgace area that will produce the maximum rate of reaction I believe I will need to use a different apparatus or a larger burette in order to hold more water since large cork borers produce Catalase samples that causes the Hydrogen Peroxide to decompose fast causing oxygen to produce quickly therefore making the water in the burette oxidise quickly.
Another experiment that I would like to conduct is varying the volume of hydrogen peroxide solution used with the use of the same cork borer sized Catalase sample. Therefore meaning the surface area and the enzyme concentration will remain the same each time. This may cause a V Max effect. In reactions within the body there is a limit to how efficient a reaction can be. This is due to there being a certain amount of enzymes available within the region. The rate of reaction within the body will increase with a greater concentration of substrates and with a greater surface area of substrates. But eventually the body region may reach its maximum ‘turn over rate’ value. Where as the Key Variables state, ‘No matter if the amount of substrate increases the enzyme can only break down a certain amount of substrates’. As there would be a fix number of enzymes in the experiment it would have a similar effect to the body region affect. Therefore it’s essential that in the body a small amount of Hydrogen peroxide is produced instead of a lot allowing enzymes to break them down easier since the enzyme will be reacting with a sufficient amount of Hydrogen Peroxide.
Another experiment that I would like to conduct is the use of an another Catalase sample. In my experiment I have used both potato and liver. The potato seemed to be not as effective as liver. This is due to that the liver is a part of a living organism who constantly requires the breakdown of hydrogen peroxide in order to perform cellular activity as I’ve stated above. Therefore it’s more necessary for the liver to have more catalyst. But with testing 2 catalyst samples I am interested about the effects of other catalyst samples. I want to discover whether their effect if their Catalase is more or less efficient than the 2 Catalase samples that I’ve already used.