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Investigating Catalase.

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ENZYMES Investigating Catalase Plan I will investigate how the concentration of hydrogen peroxide effects the volume of gas produced and how long it takes for the height of the foam produced to reach a certain height when reacted with the enzyme catalase, which is present in potatoes. In order to make my experiment fair, I must keep some factors constant: - INPUT CONSTANTS OUTPUT Concentration Volume of hydrogen peroxide Volume of Oxygen Surface area of potato Height of foam Temperature of hydrogen peroxide Cross section and overall length of potato Temperature of room Type of hydrogen peroxide Same potato pH of enzymes I chose to use concentration as my input variable. The other variables I could have changed are: - * Temperature (of Hydrogen peroxide) - changing the temperature would mean the hydrogen peroxide particles would have more energy meaning more successful collisions will occur making the reaction not only faster, but more oxygen would be collected in the same amount of time then if it was not heated. This is what I predict the graph would look like if I changed this variable: * Temperature of catalase (potato) - the temperature at which enzymes work best is called the 'optimum temperature' of 40�C. Anything below that and they slow down, anything higher than that and they become denatured. When an enzyme becomes denatured (at around 60�C), its molecules get too much energy making them unravel and so the reactant (hydrogen peroxide) would no longer fit into it. However enzymes do not die. By heating the potato to 40�C, the enzyme would be at its optimum temperature, therefore more oxygen would be collected and more foam formed. ...read more.


* If hydrogen peroxide spills onto your hand, you must wash it under water quickly 1. Arrange apparatus as shown above 2. Measure out the hydrogen peroxide and water into correct parts using a measuring cylinder then pour into test tube and measure the temperature (the temperature of the water should be room temperature) 3. Using the cylinder shaped potato cutter, get some potato and using the knife cut it to 3 cm 4. Now add the potato piece in the hydrogen peroxide (and water) and put the stopper in place. Remember to start the stopwatch at this point 5. After 5 minutes, measure the height of foam and take note of the volume of oxygen collected. Write the results in your table. 6. Repeat with the other concentrations, then repeat all four concentrations 3 times to ensure it is a fair test. I will record my results in a table: Concentration (%) Temp of (�C) Time (mins) Room temp (�C) Surface area of potato Height of foam (cm�) Volume of (cm�) SA of a cylinder= 2?rh+2?r� Diameter of cylinder cross section = 5 mm Radius (r) = 2.5 mm Height of cylinder (h) = 3 cm = 30 mm Surface area of a cylinder = 2?rh+2?r� = [2 x ? x 2.5 x 30] + [2 x ? x 2.5�] = 471.2 + 39.3 = 510.5 mm� = 51.05 cm� Obtaining Evidence Concentration (%) Temp of (�C) Time (mins) Room temp (�C) Surface area of potato (cm�) Height of foam (cm�) Volume of (cm�) 100 23 5 22 51.05 2.8 3.2 75 23 5 22 51.05 2.5 2.9 50 23 5 22 51.05 2 2.6 25 23 5 22 51.05 1.5 2.1 100 23 5 22 51.05 2.6 3.4 75 23 5 22 51.05 2.2 ...read more.


The biggest difference in volume of gas in the 'averages' graph however, was a difference of 0.6 cm� between the 25% and the 50% concentrations. In the first three graphs, the differences are only 'approximately' 0.5 cm�, because the results aren't all the same, but they are not far out. The lowest difference is 0.2 cm� in the 2nd experiment in the 'volume of oxygen produced' column between the 50% and 75% concentrations, and the highest difference is 0.8 cm� in the 3rd experiment in the 'volume of oxygen produced' column between the 25% and 50% concentrations. These differences are only 0.3 cm� more or less than 0.5 cm�, so they are still viable. There was only one anomaly in my 'rate of reaction' graph, which was the reading for the 25% concentration of hydrogen peroxide. Between the rests of the readings, there was a difference of 0.001 cm�/second, but between the 25% and the 50% concentration reading, there was a difference of 0.002 cm�/second. The reason for all these anomalies is that maybe my method slipt up a bit somewhere which meant some results were very close together and some were very far apart. The only difficulty I encountered when doing my experiments, was starting the stop watch, because I needed to put the stopper into the test tube at the same time, but I got over this problem by asking someone close by me to start it for me. I could have taken my investigation further, by heating the hydrogen peroxide to 40�C, which is the optimum temperature for enzymes. This would have meant that the enzyme would be at its peak activity rate, so more oxygen and foam would have been formed in the same time 5 minutes), because there would have been more successful collisions. ...read more.

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