To make these reactions work between the enzyme and H2O2 there must be a certain amount of force to combine them together; they have to collide to set the reaction of. The total kinetic energy of the reactant molecules must be at least as big as the activation energy if the reaction has a chance of working.
Naturally, the kinetic energy of the molecules would be higher when heated up, and so if there is a higher concentration although the temperature stays the same there will be a higher chance that because there are more molecules there will be more successful reactions, and so the overall reaction will occur much faster.
Planning
- First, I am going to fill in 250ml cylinder with water and turn it upside own with the open end under the surface of water in the trough.
- The next step is to put 50ml hydrogen peroxide into a flask and I will put 3g of liver into it. The livers have been cutted into pieces approximately 5mm x 5mm x 5mm before. Then, I will start the clock straight after I put the liver into the hydrogen peroxide solution and get the top on.
- Then, I will record the results for 10, 20, and 30 seconds.
- Finally, I will put my results in a table so that it is easy to look at.
- Then, I am going to repeat number 2 step but it would be a lower concentration. I am going to do it with 40cm³, 30cm³, 20cm³, and 10cm³ of hydrogen peroxide.
- To vary the concentration of hydrogen peroxide, the following solutions could be made up.
- Then, I am going to repeat the set of results from different concentration so that a mean value can be obtained for each time.
I will start my experiment like this:
I would need:
- Trough
- Retort stand with clamp
- A flask
- 250ml cylinder
- 50ml cylinder
- A tube
Conclusion
My prediction was proved right. My graph shows the lower the concentration is, the lower the rate of oxygen would produce. Then, the reaction would be faster if the size of the pieces of the liver is smaller. This is because hydrogen peroxide reacts with it and the reaction would be faster.
From what I got from my results and my graph, I strongly believe that by diluting the concentration of the hydrogen peroxide with water this will decrease the rate of decomposition of the hydrogen peroxide, this is because the enzymes found in the liver which are the catalysts and help the reaction to work and produce the water and oxygen. But because water molecules are now in there as well, the enzymes are finding fewer hydrogen peroxide molecules so there are less reactions taking place.
Analysis
From the results I had collected I have now plotted a graph, showing the decomposition of the hydrogen peroxide Starting to look at this graph we can clearly see that with the line of best fit drawn the points are not that far away from this line, showing a quite strong relationship.
From my graph, I find that the pattern goes up proportionally. One of my experiments shows that the rate of oxygen produced slows down from 0 to 20 seconds. When it reached after 20 seconds the graph shows it was speed up until 30 seconds. That one is experiment 5. Experiment 5 is producing less oxygen than other experiment. I think this is because there are more water molecules in hydrogen peroxide concentration.
For experiment 1, I found out that the amount of oxygen produced is increasing from 0 to 30 seconds. I also see that experiment 1 is more producing oxygen than other experiment. I think this is because no water molecules exist in the hydrogen peroxide concentration. Then for experiment 2, the graph shows that the amount of oxygen produced is lower than experiment one but the pattern is still the same. It increases as the time goes by. I think the rate of oxygen produce is lower than experiment 1 because I have put 10cm³ water into 40cm³ hydrogen peroxide.
Then, I go on experiment 3 which shows the amount of oxygen produced is lower than experiment 2 and twice times lower than experiment 1. However, it is still increasing because there is still have the reaction between enzyme in the liver and the hydrogen peroxide.
Overall, the pattern of my graph shows that the amount of oxygen produced is increasing as the time is on. However, the amount of oxygen produced would be lower if I put some water in it so the reaction will reduced.
My graph still looks a bit odd, and some of the results could be wrong, however I can still pull some conclusions from this and one is that we can definitely see that with the stronger concentration the more oxygen we are producing.
This shows how one enzyme can take on all different molecules at the same time but only if they match the write part. This means that some parts of the enzyme only accept certain molecules for reacting with. In our case the enzymes take on the hydrogen peroxide molecules to produce oxygen. As we kept the liver the same throughout the experiment the one thing that mattered to us was the concentration of the hydrogen peroxide and so as we predicted with the concentration at its highest we found we produced the most oxygen this is because there more reactions taking place and more collision and so there was a higher percentage of reactions.
From my Rate and Concentration graph, I can clearly see that with the line of best fit drawn the points are not that far away from this line and all on straight line. I believe this is because the more dilute the concentration is, the lower the rate of the oxygen produced. The reason is because the molecules of water had made the catalase enzymes (catalyst) find hard to react with hydrogen peroxide. This would decrease the reaction between them and the oxygen produced would also reduce.
Evaluation
I discover that my graph doesn’t fit the usual pattern. This is because I had only got my time until 30 seconds. That could be the cause for the graph not finished. The graph should go like this.
This is because the rate of oxygen produced will increase at the beginning of the reaction and then it will stop producing oxygen. This shows that it is finding it hard to produce a lot of oxygen because there are not enough molecules for the enzymes to react with. However, I have only got my graph like this:
I think I have lost the half of the graph. This might be because I had only got my time until 30 seconds which is a short time and it is not enough. I think it would suppose to be 60 or 90 seconds so that the graph would become what it supposed to be like.
I could improve my results by setting my clock until 90 seconds after oxygen is all filled in the 250ml cylinder. My graph shows the oxygen produced too rapidly and sometimes too slowly and this is not what I expected it to be. It should have gone slowly and constantly. This might be because I have done it wrongly and it is not perfect. I could possibly improve it by sticking the liver on the flask and once it fall down into the hydrogen peroxide solution; I would start the clock straight away.
I can also improve my graph by setting the experiment different from what I have done. For example, I could have collected the gas produced by using a syringe instead of looking at the 250ml cylinder. This could be more accurate.
A major cause for concern on accuracy was the reading of the overall measurement of the oxygen produced but also the measurements of hydrogen peroxide and water used for the experiment. So if these miss-readings were carried out through the whole investigation then my results will be quite a long way out.
Looking back on experiment I believe that there are many ways to improve it. One way is the accuracy of the measuring of the liver can be done by an electronic ruler, which has a digital screen that shows the length up to 3 decimal places. This would make every liver I use virtually the same length and thickness by using the same size and so this ensures reliability from this.
My graph is very basic and one way to improve this will be to increase my range off tests. This will give me more results and so when I plot my graph again there will be more points producing a greater accuracy and a better curve with which we will be able to pull stronger conclusions from.
From my experiment, I have found out other factors which might change the result. For example, surface area of the liver, temperature of liquid that is reacting, the concentration of the liquid or the amount used are going to be the major variables in the experiment.
