Variables
Dependant Variable: Time, Size of 5cm piece of Potato
Independent Variable: Amount of Oxygen released
Control Variable: Volume of Hydrogen peroxide, size of Potato, concentration of Hydrogen Peroxide
Hypothesis
I predict that the breakdown of Hydrogen Peroxide will be quicker when the surface area is increased. If you cut the same size piece of potato into smaller pieces, I believe, the breakdown will be faster. I predict that an increase in surface area will result in an increase in kinetic energy. Since the size of the area increases, I think that more oxygen will be released from the Hydrogen Peroxide and Catalyse.
We will be measuring the two main factors: -
- Oxygen – the amount released from the Hydrogen peroxide
- Time – The duration of the reaction
The room temperature may be a factor that will affect our results. Therefore we will have to try our bests to inure the test is carries out under the same conditions.
To make it fair we will allow the reactions to have the same amount of time to occur. We will only change the amount of catalyse in the tube.
To obtain the best possible results I will repeat each experiment three times and then find the average set of data to plot my graph. Our measurements will be very precise as we will carry out the experiment as safely and fairly as possible. We are using accurate apparatus to allow us to achieve this.
Investigation Experiment
I am going to investigate how the enzyme, Catalyse reacts at different surface area sizes. The procedure for the experiment is as follows;
- Set up the apparatus
- Place the water in the water bath
- Fix the inverted measuring cylinder so that the delivery tube connects to the boiling tube
- Using a measuring cylinder, measure 10ml of Hydrogen Peroxide
- Measure 5sm of potato and add to the Hydrogen Peroxide solution in a boiling tube
- Immediately place the bung on the boiling tube, as the reaction would have already started
- Set the timer for 3 minutes. Repeat the experiment three times (for accuracy) using the different pieces of potato
- It is important only the size of the potato is changed, since that is what is being investigated
Results
Scientific Knowledge
They way enzymes work is that they have a lock and key mechanism. The catalyse can only be broken down when the enzyme has the correct combination that will fit into the catalyse and allow it to be broken down.
Conclusion
My results proved that my hypothesis to be correct. The breakdown of Hydrogen Peroxide accelerated as the surface area increases.
With less surface area the rate of reaction is not as much as it could be. When you cut the potato into smaller pieces this allows a greater surface area to be used by the Hydrogen Peroxide. Therefore the rate of reaction increases.
Enzymes are specific in the reactions they catalyse, much more so than inorganic catalysts. Normally, a given enzyme will catalyse only one reaction, or type of reaction. The enzyme has an active site that helps it to recognise it’s substrate in its own specific lock; each enzyme has its own specific substrate. This is called the lock and key theory. The enzymes never actually get consumed in the process; they just increase the rate of reactions.
Evaluation
Overall I would like to think my experiment went alright. Almost everything went according to plan. We followed our safety instructions and did the experiment fairly and accurately as possible. Therefore the majority of my results came out to be reliable and accurate. Due to using the equipment safely and accurately this experiment has been successful.
However, there were a few results in the experiment that do no agree to the scientific information. When measuring the amount of Hydrogen Peroxide, we may have not measured the exact amount. We could have accidentally measured 10.1ml; instead of 10ml. another problem was the temperature of the room. As we carried out the experiment on different days, some times the temperature in the room varied, from 23C to 30C. This may have affected the particles in the enzymes, causing the reaction to occur slightly faster than it should or slightly slower. Luckily there were few spillages of Hydrogen peroxide, as we used the equipment safely and accurately. There was air/water in the delivery tube prior to the reaction which may have delayed the oxygen getting through. Also the condition and variety of potato could have affected the results because some the potato could have been four weeks old and the others only just freshly cut.
