The document summarizes a student's biology lab experiment on the effect of adding increasing amounts of catalase enzyme to hydrogen peroxide solutions. The student's hypothesis that the rate of gas production would increase as more catalase was added was supported by the results. The average rate of gas production increased from trial to trial as 1, 3, 6, or 9 droplets of catalase were added. However, the expected leveling off of the reaction rate with sufficient catalase was not clearly observed. Limitations included inconsistent droplet sizes and potential contamination between trials.

1. Annie Chiang<br />IB Biology HL<br />Period 2<br />Catalase Activity Lab<br />Introduction:<br />Enzymes are proteins that catalyze chemical reactions (increase the rates of biological reactions).The reaction that will be investigated in this experiment is the decomposition of hydrogen peroxide:<br />2 H2O2 (liquid) -- Catalase 2 H2O (liquid) + O2 (gas)<br />When a catalase enzyme is added to a hydrogen peroxide solution, it becomes water and oxygen gas. <br />Hydrogen peroxide is an oxidizer commonly used in bleach. It is a clear liquid and is used as a disinfectant, antiseptic, and oxidizer. All cells in our body produce hydrogen peroxide – sometimes as part of your immune system to kill bacteria, sometimes as a byproduct of metabolism, but either way your body must have a way of protecting itself from its own hydrogen peroxide. <br />Air pressure will be used to measure the rate of reaction in which hydrogen peroxide is changed into water and oxygen gas. The standard atmosphere is a unit of pressure and is defined as being equal to 101.352 kPa (Wikipedia). <br />Gas pressure probes will be used in this experiment to measure the amount of pressure in the test tubes after Catalase is added to a hydrogen peroxide solution.<br />Hypothesis:<br />The production of gas will increase as more droplets of liver catalase are added into the hydrogen peroxide. There is probably an optimal rate of increase where the rate levels off after a certain amount of catalase is added to the hydrogen peroxide solution.<br />Data Collection:<br />Table for Trials of One, Three, Six, and Nine Droplets of Liver Catalase vs. Rate of Gas Production<br />1 droplet (kPa)3 droplets (kPa)6 droplets (kPa)9 droplets (kPa)Trial 10.2020.5111.2421.609Trial 20.1340.6921.0474.561Trial 30.0460.5871.6776.495Trial 40.0670.5351.4032.207Trial 50.0290.5891.3141.389Average Rate of Gas Production0.0960.5831.3373.252<br />Conclusion and Evaluation:<br />According to the data collection, my hypothesis is correct because the rate of gas production increased as more droplets of liver catalase was added to the hydrogen peroxide solution. As seen on the data table, the average rate of gas production increased as more droplets of liver catalase is added into the hydrogen peroxide. The slope of each graph demonstrates a steeper slope as the droplets of catalase is increased. Hypothetically, it is assumed that there is a optimal level in which the gas production rate is working, but it is not seen in the results of this experiment. In order to be sure this is true, another experiment could be conducted and increase the number of droplets of catalase that is being added to the hydrogen peroxide. Although it’s not as visible, in the graph with three drops of liver catalase, we can see a little bit of the rate leveling off as all the hydrogen peroxide molecules have been changed into water and oxygen gas; this means that even with more than enough enzymes are added, it would not keep speeding up the rate of production if all the molecules have already been changed into another form.<br />Some limitations of this experiment could be the consistency in putting the correct and same amount of catalase into the test tube for each trial; some droplets may vary in size depending on how hard the pipet was squeezed, so this could have caused the inconsistency or inaccurate results. Another limitation could possibly be the re-usage of test tubes and not having the test tubes washed thoroughly, which could have left some catalase in the test tubes, which could affect the results of the experiment. Another limitation could possibly be the use of technology, loggerpro more specifically, because it may not be accurate because of not calibrating the equipment. <br />Improvements that could be made could possibly be using different test tubes for each trial so that it is 100% washed without having previous liver catalase or hydrogen peroxide left over in the test tubes. Also, the equipment used to calculate the rate of gas production could possibly be calibrated before the experiment to ensure there are no problems with the equipment. Also, make sure that the cap on the test tube is tightly closed so that no gas is being released. <br />