Apparatus: The equipment which I will use are; 5 test tubes, a test tube rack, borer to cut the chips the same shape, weighing scales, stopwatch a measuring cylinder and a pipette.
Preliminary work: For my preliminary work I tested 4 different weights of potato and used 10cm³ of hydrogen peroxide solution. We then put 2 drops of fairy liquid inside each test tube which had the potato chips (0.7g, 1.5g, 3g, 4g, 5g,) in each solution. Then timed it for 5 minutes. Because of our preliminary work we found that we should use smaller potato chips so the foam doesn’t go over the top and therefore become an anomalous result as we could no longer measure it and that we will record our results every minute for ten minutes as it will allow us more time to measure each bit of foam from each test tube. I will also use 15cm³ of hydrogen peroxide instead of 10cm³. The bigger the froth the more reaction has taken place.
Measurements: The things which I am going to measure are the amount of froth appeared after the reaction at 1 minute intervals. I will measure the weights for the potato catalase to ensure they are as accurate as possible. (0.5g,1g,1.5g,2g,3g.). I also need to measure the amount of hydrogen peroxide used in cm³.
The diagram below will explain how I will set up my investigation.
Method:
- First I collected all of my apparatus; borer, weighing scales, 5 test tubes, a test tube rack, stopwatch, a measuring cylinder, pipette, fairy liquid, hydrogen peroxide and potato catalase.
- Next I poured 15cm³ of hydrogen peroxide into each test tube after measuring it in a measuring cylinder. I then placed each test tube in the test tube rack.
- I then cut out each of the weights of potato catalase out of each potato using a borer before weighing them to make sure they were the right size and weight. (0.5g, 1g, 1.5g, 2g, 3g,) before placing them in each test tube. I then labelled each test tube with the weight of potato catalase on the front so I didn’t mix them up.
- I then put two drops of fairy liquid into each test tube of the solutions and started the stopwatch.
- At 1 minute intervals we measured each of the test tubes to see how much froth there was and recorded our results.
- After ten minutes we stopped and cleared away.
Safety: To make my investigation safe I will where goggles and tie my hair back at all times. I will remove all coats and bags out of the way to avoid me falling over them. I will put the test tubes in a test tube rack in order to stop them being knocked over and broken. I will use the equipment carefully and clear all used equipment out of the way to prevent them getting in the way. I will roll up my sleeves and remove my chain to stop it getting in the way of our experiment.
Here are my results:
I have drawn a graph of my results.
Looking at my graph I can see the faster the reaction the bigger the chip. The slower the reaction the smaller the chip. On my graph it shows the amount of froth in cms and the more froth there is the bigger the reaction there is which means there was a bigger chip used.
In my investigation I found that more enzymes (bigger potato catalase) the faster the rate of reaction. I think this happened because of the lock and key theory and the collision theory which I used to help describe my prediction. It is when a subtrate of the right size fits into the active site then breaks into two separate compounds (lock and key theory). The collision theory is when the particles build up enough activation energy to collide and cause a reaction.
I think my prediction was spot on with the results as I have said above as I predicted that the bigger the chip the faster the rate of reaction and that is what has happened. I also used the lock and key theory and collision theory in my prediction which I believe has happened.
Evaluating my evidence:
I think the way I carried out my experiments was fairly well because my predictions matched my results and judging by the results I got I didn’t have many anomalies although the results for the 3g of potato catalase was an anomaly because the froth spilled over the edge so we couldn’t measure it so we repeated the test for 3g of potato catalase using a longer test tube so the froth didn’t flow over the edge. The results now are fairer and more accurate because I repeated the test for the anomalies of the 3g of potato catalase.
The results were out of place for 3g of potato catalase because the froth flowed over the top so we repeated the test and now the results are more accurate
In my investigation I had a few anomalous results for the 3g of potato catalase so we repeated the test in order to get fairer results. These anomalies occurred because the froth built up so much it poured over the top so we could no longer record the results as it would just stay the same. To overcome this problem we repeated the test for 3g of potato catalase using a longer test tube so the forth didn’t flow over the top and now our results are more accurate.
If I had to use my results as evidence they show that the more potato catalase used the faster the rate of reaction. The reason I think this happened is because of the lock and key theory and the collision theory where the subtrate fits and locks into an active site then splits into two separate compounds (lock and key theory). The collision theory is when particles collide (when they have enough activation energy) to cause a reaction.
In order to make my investigation better I should have staggered the results at the start time so when I measured the foam I had enough time to measure each one rather than rush through them all at the same time so that only the 1st would be on time but by the time you get to the 5th you would be at least 10 seconds into the next minute so the 5th had an unfair advantage as it had an extra 10 seconds. I f I were to stager the start time I could do them 5 seconds apart so I have enough time to measure each one.
To get further evidence I could use different volumes of hydrogen peroxide and the same size chip to see if that affects the rate of reaction. I could use more fairy liquid or put them all at different temperatures to see if that varies the rates of reaction.
