Safety
The safety features in this experiment are to wear goggles when using the hydrogen peroxide, so it doesn’t get in to your eye and everyone should have coats hanged up, as H2O2 is a bleach and it will take colour out of your clothes. In addition, there should not be any stools in the gangway as people might trip over them.
Variables.
In this experiment, the variables are the temperature, amount of hydrogen peroxide and the amount of potato. In this case, we are going to investigate temperature so the other two will not change. The amount of potato or H2O2 will not change, as this will make the test unfair and inaccurate. The temperature needs to change because we need to investigate that.
Fair test.
To make this investigation a fair test you should only change one of the variables. In this case, we are investigating temperature so we will not change any thing else. We will not change the amount of potato and the amount of H2O2; we are not trying to experiment with these to things. Also, make sure you try to put in exactly the same amount of H2O2 each time and that you try to be as accurate as possible when cutting the potato. When doing repeat readings keep the same variables as your first set of results. Doing repeat readings will make your results more reliable and accurate. All these things will try to make it a fair test. If the test is unfair, it will affect your results.
Prediction.
I predict that the higher the temperature will be the faster the reactions will be, therefore there will be more active site’s and more molecules will be broken down faster. The enzyme and the substrate work like a key and a lock. The enzyme is the lock and the substrate is the key. (See diagram) When the temperature is raised, more fits are successful. Enzymes work best at body temperature, which is 37 c. However, I think that if the temperature goes over 50 degrees the enzymes will stop working or start to become inactivated. When an enzyme is inactivated its shape changes this is called denature, and it can no longer fit the substrate (See diagram). As we are investigating temperature, the collision theory plays a big part in this experiment. The collision theory says that particles react by colliding with each other, if they get hotter the move around faster because they have more energy, so therefore causing more effective collisions (see diagram). Therefore, when we increase the temperature we increase the rate of reaction with it. Therefore, even if there was a small amount of enzyme and a large amount of substrate the reactions will be fast. The bubbles that are produced are oxygen bubbles. By counting the number of bubbles produced, we get an idea of how fast the reaction was. Oxygen is one of the products of the reaction. The formula for this experiment is:
H2O2 2H2O + 02
Catalayse
Diagrams.
HOW ENZYMES WORK.
RESULTS TABLE.
COLLISION THEORY.
When particles get hotter, they get more Energy so they move around faster, therefore causing more successful collisions which make the reaction faster.
Note*
Amount of hydrogen peroxide = 15ml
Amount of potato = 1 cm cubes
= Movement
Here is the table of results with the average amount of bubbles produced.
We can clearly see that the results show a pattern: the higher the temperature the more bubbles produced therefore the faster the reaction. When the temp is at 50 we can see that there is a drop in the number of bubbles produced showing that the enzyme is inactivating.
Conclusion.
In this experiment, I have found out that the higher the temperature the faster the rate of the reaction. The number of bubbles increased as I changed the temperature for the enzyme. This answer is supported by the collision theory. Therefore, as the particles were hotter there were more successful collisions, therefore faster reactions. I have also seen that if the temperature went over 50 c the enzyme stops working or became inactivated. This happened because as the temp went over 50 c the shape of the enzyme changed and it couldn’t fit the substrate so it couldn’t break down the molecules. The enzyme and the substrate work like a lock and a key and if one of them is broken the lock will not open. I can also see a clear pattern in my results and in my graphs. But the graph looks a little awkward because the last reading doesn’t really fit in the pattern, but I know that this is ok because I had predicted that this would happen. My results match my prediction, so what I had predicted was correct. I also think that I have enough evidence to support my conclusion and my prediction. The main pieces of evidence are my results table and my graphs. While I was collecting results, I did three repeat readings to make sure that my results were accurate and reliable. Then I had to find the average of the three readings, to get a reliable set of results. By completing this experiment, I have found out the answer to my aim.
Evaluation
In this experiment, we were trying to find out how the temperature of the substrate affects the rate of reaction with the enzyme. I think that this experiment was not very accurate because there were a number of measurements that we could not get right. E.g. cutting the potato into 1cm cubes, having the exact amount of H2O2 each time, and how much oxygen was given off in each reaction. We could improve this if we had more precise measuring equipment, like a 15 ml measuring cylinder, so we could just fill it to the top. When we were counting the number of bubbles made in 1 min, I noticed that they were not all the same size that means that different amounts of oxygen were given off each time. We could extend this investigation by recording how much oxygen was made by the reaction. To do this we would need a syringe on top of the test tube and we are able to see how much oxygen was being made. The evidence that I produced was not 100% accurate, but we could make the results more reliable by doing more repeat readings and making it a fairer test. My results matched my prediction, although the last reading was awkward and did not fit in the pattern when you looked at it. However, I knew that this was ok and it should have happened because I had predicted that the enzyme would stop working after 50 c, as it will be inactivated.
