Fair test- It is important to make my experiments as fair as I possibly can. Otherwise if I change other factors or in any way make my experiments unfair then I will not get true results. Therefore my results will be worthless. An in addition I will not be able to draw a conclusion and find out about my aim of the experiment (which is the whole purpose of doing this investigation).
I completed a pilot test in order to find out and to get familiar with the experiment. I now know what I have to be careful of not to change to make my experiments fair.
I will make sure that I use all the same equipment for each experiment e.g. the same measuring cylinders as there measurements might be slightly different to other measuring cylinders.
I will also complete each experiment five times so I can get an average of the experiments. An average is good because that way I will collect lots of results and make my test more fair, then get an average of those results (as they will probably vary). Also the average will not be affected too much by extreme values (really high results and really low results).
I will also only change one factor or variable in my experiment, temperature. This is so I will know who temperature is affecting the experiment. Otherwise if I change other factors e.g. amount of liver, amount of hydrogen peroxide) then these will affect the experiment in different ways so I will not be able to tell how temperature had affected the experiment.
I will always use liver in my experiment rather than changing substances that also contain the enzyme catalyse (e.g. potatoes).
I will also use the same amount of liver and hydrogen peroxide in each experiment. I will use 1ml of hydrogen peroxide and 3 drops of liver.
How I will keep my experiments safe- It is important for both me and other people around me that I keep all my experiments safe.
I will try not to spill any hydrogen peroxide (on the floor and on anyone or even myself). If I do I will clean it up immediately, as in the same way that I will do so with the liver.
I will make sure that I wash my hands after each experiment, in case I have any hydrogen peroxide on my hands.
I will make sure that I do not drink any of the hydrogen peroxide or liver.
I will make sure that stalls are placed under a table (where I am working), to avoid people fall over them.
I will stand up for each experiment rather than sitting down.
Prediction- I know that enzymes and particles are affected a lot by temperature. If you heat up particles then they will collide more into each other and therefore cause a greater reaction the more they collide (Collision theory). This is because they have more energy and move around more. So this is why they particles will collide more, because they will travel faster (and obviously cause more collisions). And from this I could predict that the more I heat up the particles the more energy they will have and therefore will travel faster, and in affect cause a greater and faster reaction. Also the other reason for why the rate of reaction will increase is because some particles collide but do not have enough energy to cause a reaction. Therefore if the particles have more energy then they will collide harder as they go faster and there bang will cause a reaction. From this information that I know I could predict that as I raise the temperature of the particles (as I raise the temperature of the liver) there will be a greater reaction as the particles will have more energy to collide. But, I also know that all enzymes are proteins. At high temperatures the protein breaks down. Now the active site has changed, now the substrate will not fit. The enzymes have now been denatured, and in affect will no longer work. (See diagram below).
I now will have to change my prediction from:
The more I heat up the particles in the liver; there will be a greater reaction. This is because as I heat up the particles they will have more energy and therefore travel faster and collide more.
My prediction will now be:
I think as I increase the temperature of the particles in the liver, there will be a greater reaction. But once I exceed a certain temperature, then the protein will break down. This means that the substrate will no longer fit. And therefore the rate of reaction will lower.
Once I complete all my experiments I will put them into a graph. I think that the graph will form a kind of curve. This will happen if I have enough data, and also because the rate of reaction will go up then lower once I exceed a certain temperature which then the enzymes will be denatured.
Plan- I will place 1ml of hydrogen peroxide in a measuring cylinder.
I will then place 3 drops of liver in that same measuring cylinder, using a pipette.
After, I will time the two substances in the same measuring cylinder for 40seconds, using a stop watch.
I will repeat this 5 times for each temperature.
I have now collected all my results. All results are close to each other so I know that I must have done all me experiments very similar to the last.
I have made my readings as accurate as possible by not rounding off measurements and including necessary decimal points.
I have done enough tests to have a wide range of accurate and reliable results because all results are close, so there is no need to continue any more experiments.
My graph and results show that my prediction was right. From my graph I can see that as the temperature went up so did the rate of reaction. (I measured the rate of reaction by the amount of foam that appeared which was the reaction of both substances). Then once the temperature got to a certain heat then the rate of reaction decreased. This happened because once the particles got heated to 50º the enzyme then became denatured which lowered the rate of reaction.
If I had more data then my graph would have be a smooth curve. From my graph I can see that there seems to be quite symmetrical distribution so this means that the distribution of my data is more or less symmetrical.
So when I look at my data I could predict (by looking at my line of best fit) that at 20º the average height of the foam would be 2.4. I can continue to do this just by looking at my line of best fit on my graph.
From my data I can also see that the power or energy of the particles increased up until 50º then there energy decreased.
My results support my original prediction because I said the rate of reaction will increase (or the height of foam) will increase until a certain point then the rate of reaction will decrease. My prediction has been proved because at 50º the rate of reaction then started to decrease. Therefore that is when the enzymes became denatured.
My results fit well into my line of best fit. There is one value that does not fit, but this could just be due to one result being slightly wrong. But even though the value does not fit in to the line of best fit it does come close to it.
The repeated readings for each test were reliable. I know this as there is little difference between most readings in the values for the repeated readings.
I think I could improve my method by getting more accurate results. I could get a more accurate measuring cylinder that goes into smaller values. I could/should have used 05ml of liver rather than using 3drops. As 3drops is not very accurate, one drop could be larger than another. And a drop is not a measurement.
Although a lot of my results are similar there are one or two that there is a large range for example for the temperature of 60º there is a range of 3 (5-2) this is quite a big range and could of affected that data. Also the average for this does not fit in to my line of best fit. So if I were more careful when measuring then, this average that was a little of line, may not of been and would have fitted on my line of best fit.
I think that the anomalous result(s) that I did get (well just for the temperature of 60º) is because the drops that I used of liver were not very accurate. For one of my results that I got for that temperature (of 60º), I may have used slightly less liver (as I used a pipette the drops I used may have been smaller than others), causing there to be less particles and therefore a smaller reaction. This could explain one of the smaller reactions. Or if I used more liver in one of the experiments for that very temperature (of 60º) this would have caused a greater reaction, therefore this could explain one of the greater reactions I got. All of which I should have used a more accurate measure of liver. Though this is the only temperature where my results has been slightly off the line of best fit, so to a certain degree my measurements must have been fairly accurate, just not accurate enough. This shows my experiment was slightly unfair.
I think I have collected enough results. All my results are fairly similar, and therefore I felt there was no need to continue to do anymore experiments. So from my results I think I can draw a firm conclusion.
Conclusion- I think that an important and key factor that very much affects the rate of reaction between Catalyse and Hydrogen Peroxide is temperature. The rate of reaction increases up until 50º. After this temperature (so above 50º), the enzymes in the liver get denatured, and therefore the higher the temperature past 60º, the lower the rate of reaction will be. So temperature in this investigation affected catalyse (catalyse in the liver) and hydrogen peroxide by affecting the rate of reaction between the both, by either slowing down the rate or making the reaction faster.
I could extend this investigation, which would still aim to find out more about the influence of the same factor, by looking at higher temperatures and/or look at different reactants. By extending my investigation I will again a greater understanding of my investigation and aim. I could also extend my investigation by looking at time. I could see how long (at different temperatures) it takes for the two substances to stop reacting. I could also extended my investigations by looking at different substances that contain catalyse. Or I could look at the surface areas and/or weight of the substances (e.g. I could use a chunk of potato and weight it or look at its surface area). If I was to extend this investigation, in any way, I would make sure I used accurate measurements e.g. 0.5ml of liver rather than 3 drops. And still continue to make my experiments as fair as possible.
