Molecules used up with substrate.
so you add more Substrate is constant.
H202 the rate stays
the same.
Plan - How are you going to do the experiment?
In my experiment I am going to use the catalase yeast because it gives a faster rate reaction, also I will be using a solution of H2O2, which comes neat 6% and 40 volume.
A table of results to show the percentage of water
The temperature that will be used will be room temperature and
The size of volume that will be used will be in 30cm3 portions
From my preliminary work I found out that I need to use: -
A range of food substances that contain catalase such as liver, apple and yeast. I also tried a range of concentrations of hydrogen peroxide 1% through o 6%. From this testing we found that yeast was the easiest to use, cheap and moldable. Liver was too smelly and apple gave to slow a reaction time. Tim e was tried out at 1, 2, 3, 4and 5 minute intervals. We found that 3 minutes gave a result that could be measured.
From this information I will use yeast as my source of catalase and a range of H2O2 from 6% to 1%
The aim of the investigation is to find out what happens to the substrate when the catalase is diluted with water. Whether or by how much it changes the rate of reaction.
The variable I am going to change is the concentration of the substrate (hydrogen peroxide)
Plan
The aim of the investigation is to find out if changing the concentration of the substrate will change the rate of reaction.
The variable I am going to change is the concentration of hydrogen peroxide.
What I am going to measure is the amount of oxygen given off (cm3) in a certain time (3min). This will tell me the rate of reaction (volume /time)
What I think I will find out is that the higher concentration of the substrate will have the higher rate of reaction. This is because the higher concentration will have more activation energy, which will produce more collisions and harder collisions. This will make the particles gain more heat that will lead to the particles reaching the activation energy. This will happen quicker with the higher concentration.
I will carry out the following method using 0.5 gram ball of yeast, 100cm3 of substrate and catalase in a conical flask with a bung attached via a tube to a large measuring cylinder full of water in a beaker filled with water. When the oxygen bubbles are produced they go through the tube in to the measuring cylinder where they are measured by the water they have substituted.
O2 bubbles Measurement of O2 produced
Stop clock
Tube
Conical flask
Beaker
Water
Substrate (H2O2)
Yeast
Observation
I will carry out 5 measurements
I will carry out measurements from 1% to 6%
I will take the following precautions to make sure my results are accurate such as always measure the correct amount of substrate and keep the conical flask at the same temperature all the time. Also I will make and stop the experiment dead on 3 minutes. I will wash the conical flask to rid any substrate and thoroughly dry any water that was in it so that my measurements were exact.
Table to show oxygen produced (cm3) in 3 minutes
Analysis
The trend of my result is: - The higher concentration of substrate, the faster the rate of reaction went. The lower the concentration rate reaction was slower.
The results that back this up are: - My results table shows more hydrogen bubbles were produced with the higher concentration of substrate. The results from my graph back this up because the graph has a line of best fit that shows when the concentration of the substrate is weaker it takes longer to react with the same amount of yeast and doesn’t produce as much bubbles in 3 minutes as the higher concentration of substrate does. This means it has a slower rate of reaction.
The scientific reason for these results is: - that the higher concentration of substrate has more energy in its particles therefore produces bigger collisions and more of them reach the activation energy quicker which is when they become a product. The lower concentration has not got as much energy in its particles as the high concentration so therefore takes longer to reach the activation energy because its collisions are not as big and there are not so many of them. This means it will take longer to produce the product and will have a slow rate of reaction.
Evaluation
The limitations in my method were: - That we could not measure the 0.5 gram balls of yeast precisely enough. We could have affected the results. Also we could not try the measuring cylinder thoroughly so that could have affected the results.
I think these affected my results because: - The 0.5 gram of yeast could have been heavy which would make the rate of reaction faster or could have been a little less which would make the rate of reaction slower. Also the water in the measuring cylinder would have made the reaction go slower.
The limitations in the equipment I used were: - The measuring cylinder had too many gaps in the measurements so we could not measure precisely and the stop clock had a delay so we got a slower time.
I think these affected my results because: - We could not measure precisely how much hydrogen bubbles were produced and the results may have been slower in the delay of the stop clock.
My anomalous results were in the 5% concentrated. I think these may have happened because some of the pupils diluted the substrate, which made the rate of reaction very slow.
The changes I would make to my equipment and method if I did this investigation again are: - That I would have my yeast balls precisely measured and have a large measuring cylinder with small measurements for small precise measure. Also I would make sure the beaker and measuring cylinder were completely dry.
What I would do to extend my investigation is: -to see if the pattern was the same if I used a gram ball of yeast instead of a 0.5 gram. Also I cold use bigger concentrations of hydrogen peroxide and in small concentrations like 1.5% then 2% and so on.