Lab Report The effect of temperature on the reaction between Catalase and H2O2 Sarah AlShemesi In this experiment we’ll be exploring the effects of temperature on the reaction between Catalase and H2O2. We’ll be using five different temperatures to test this. The five different temperatures will be 10, 30, 50, 70 and 90 oC. We will use the liver as a source of Catalase. A 1 gram piece of liver will be inserted into a test tube with 2 cm3 of water, then 2 cm3 of H2O2 will be added.

The Catalase and H2O2 are expected to react and result in bubbles and a rise in the solution. If the bubbles form and the solution rises quickly then this suggests that the enzymes are working sufficiently and the nearing the optimum temperature. Investigation question: What is the effect of the different temperatures 10 oC, 30 oC, 50 oC, 70 oC and 90 oC on the reaction between Catalase found in liver and H2O2 and what will be the Catalase’s optimum temperature? Variables: * Independent variable: Temperature in oC Dependant variable: the height of the solution, measured with a ruler in cm. * Controlled variables: mass of liver, volume of water, volume of H2O2, method of pouring H2O2 into the liver/water solution. * The mass of the liver was controlled by measuring the liver pieces after they’ve been cut to ensure that each is 1 gram only. * Volume of water was controlled by measuring 2 cm3 using the same 10 cm3 measuring cylinder. * Volume of H2O2 was controlled by measuring 2 cm3 of it using the same 10 cm3 measuring cylinder. The method of pouring the H2O2 into the liver/water solution was kept consistent by having the same person pour it in every time at the same approximate speed. Materials: * Liver * H2O2 60 cm3 * 1 Ruler ( cm ) * Water 60 cm3 * 12 Test tubes * 2 Tongue * 2 Measuring cylinder 10 cm3 * 2 Droppers * 1 Beaker 100 cm3 * A bowl of ice cubes * 1 Knife * 1 Bunsen Burner * 1 Glass rod * 1 Digital balance * 3 Thermometers ( oC ) Method: 1. Cut the liver into twenty five pieces using the knife, use the digital balance to ensure that each piece of liver weighs 1 gram only. 2. Place each liver piece in an individual test tube. 3.

Use the 10 cm3 measuring cylinder to measure 2 cm3 ( this amount of H2O was chosen so that when the H2O2 is added the solution can bubble and rise without spilling out of the test tube ) of H2O and add that amount of water to the test tube containing the piece of liver. 4. Place ice cubes at the bottom of the 100 cm3 beaker till the base of it is completely covered. 5. Place the previously mentioned test tube ( containing the water/liver solution) into the beaker holding it up at the center as you or your partner continue to fill the beaker with ice cubes till the test tube is completely submerged in ice and only the top is not. . Continuously measure the temperature of the solution. 7. When the solution reaches the temperature of 10 oC, remove the test tube from the beaker filled with ice and perform step 8 immediately. 8. Add 2 cm3 of H2O2, wait for the solution to react and for the bubbles to rise and then use your cm ruler to measure the height of the solution after it has risen and note the height down. 9. For the other trials you must heat your solution rather than cool it down. To do so, prepare your liver/water solution with the same dimensions as before. 0. Light up the Bunsen Burner to a soft flame. 11. Use the tongues to hold one test tube over the flame, you must move the test tube continuously to avoid burning or overheating and you must also measure the temperature of the solution continuously till it reaches the desired temperature for that trial; either 30 oC, 50 oC, 70 oC or 90 oC. 12. When the solution reaches the desired temperature quickly repeat step 8. 13. Repeat the procedure five times for each temperature to produce five trials.

Data collected on the effect of Temperature on the reaction between Catalase and H2O2: This Date shows the temperature, the final height of the solution in the test tube after it rose and the change in height given that the initial height for all is 1. 4 cm. | Height of solution ( cm ±0. 1 )| Temperatures ( oC ± 0. 5 ) | Trial 1| Trial 2| Trial 3| Trial 4 | Trial 5| Mean of change| | Final height| Change in height| Final height| Change In height| Final height| Change in height| Final Height| Change in Height| Final Height| Change in height| | 10| 2. 1| 0. 7| 2. 3| 0. | 2. 2| 0. 8| 2. 4| 1. 0| 2. 3| 0. 9| 0. 9| 30| 2. 6| 1. 2| 2. 7| 1. 3| 3. 0| 1. 6| 2. 8| 1. 4| 2. 6| 1. 2| 1. 3| 50| 3. 1| 1. 7| 3. 2| 1. 8| 3. 3| 1. 9| 3. 1| 1. 7| 3. 4| 2. 0| 1. 8| 70| 2. 5| 1. 1| 2. 4| 1. 0| 2. 6| 1. 2| 2. 7| 1. 3| 2. 4| 1. 0| 1. 1| 90| 1. 4| 0. 0| 1. 4| 0. 0| 1. 4| 0. 0| 1. 4| 0. 0| 1. 4| 0. 0| 0. 0| Uncertainties were calculated by finding the lowest unit of the measuring equipment and then dividing it by two. For example the lowest unit of measuring on the thermometer is 1, to calculate the uncertainty: 1 / 2 = 0. 5 So the uncertainty is: ± 0. However in the case of height, we’re using both ends to measure so we don't divide by two. So since the smallest measuring unit is 0. 1 cm the uncertainty is ± 0. 1 Table 2 : Standard Deviation of each trial : Temperature ( oC )| StandardDeviation ( cm) of Data| 10| 0. 10. 1| 30| 0. 149| 50| 0. 116| 70| 0. 116| 90| 0. 000| The standard deviation was calculated using a TI-83 GDC. The steps were the following: 1. STAT ; EDIT ; Edit :1 2. Enter the variables ( In this case, the change in height in the different trials of the same temperature ) under L1. . STAT ; CALC ; 1-Var Stats to view the values. 4. Standard deviation is displayed as Sx. The standard deviation will be used on the graph to indicate how much results may deviate from the collected data. I could further process my data using the T-test or the Chi squared test to see whether there is a clear correleational link between temperature and height of the solution of water/liver after it reacts with H2O2. However, I will study this correlational link through the following graph: Temperature of Liver/Water solution ( oC ± 0. 5)

Change in Height of the Liver/Water solution after H2O2 was added. (± 0. 1 cm) The trend line is polynomial ( Order : 3 ) so it shows the predicted heights of the liver/water solution after H2O2 is added against the temperatures. Conclusion: Our data shows that the enzymatic activity of Catalase varied depending on temperature. At 10 oC the activity decreased because the Catalase molecules moved slower thus resulting in less collision with the H2O2 molecules. In the temperature 30 o C we find that the activity increases slightly because the molecules are colliding more often.

However we notice that at the temperature 50 oC the activity is the highest and has significantly rose above the others. This suggests that at the temperature of 50 oC Catalase is most sufficient; it is the optimum temperature. The trend line’s curve also supports that since the curve is highest at 50 oC. At 70 oC the activity decreases and the solution rises almost as high as it did at the temperature of 30 oC, this is due to the enzymes denaturing because of the high temperature. At 90 oC we observed no reaction whatsoever because all the enzymes had denatured.

Our graph was very similar to the one found in the Pearson Baccalaureate SL Biology book that displayed the effect of temperature on Catalase activity. They both exhibited a steady rise followed by a steep decrease, as the temperatures got higher. My data and graph also clearly suggest that the optimum temperature for Catalase is around 50 oC while an experiment conducted by Arefan Khan concluded that 40 oC is the optimum temperature for Catalase (Effect of Temperature on Catalase Enzyme, pg1).

The different results may be because I had large intervals of temperature; I did not test for the effect of 40 oC on Catalase, which is why my results are closer to 50 oC. Evaluation: Error 1: -Step: cutting the liver Weakness: the liver wasn't frozen and so the cutting was not very accurate. This resulted in us cutting small pieces of liver to complete 1 gm, thus resulting in different surface areas for different trials and temperatures. This may affected the experiment by exposing more Catalase to the H2O2 in some trials than others.

Improvement: Make sure the liver is frozen and can be easily cut so that all trials receive liver with roughly the same surface area. Error 2: -Step: Using the Bunsen Burner to heat the solution to the desired temperature. Weakness: the temperature of the solution continued to rise even after heating was stopped. Improvement: Using an electric water bath and setting it to the different desired temperatures to heat the liver and water solution to ensured that temperature is constant. Error 3: -Step: Using the Bunsen Burner to heat the solution to the desired temperature.

Weakness: The thermometer’s temperature might have affected the temperature of the solution when it was inserted into it to measure its temperature. For example: the thermometer is at room temperature and is inserted into solution being heated to 70 oC, the solution might haven risen above that, however when the thermometer is inserted, it cools down the solution and gives a temperature of 70 oC. Improvement : Keeping the thermometer inside the solution as it is heating or cooling, however it must be ensured that it does not touch the bottom of the test tube as that may give false temperatures.