Enzymes are a protein catalyst that speed up the rate at which a chemical reaction occurs. Hydrogen peroxide is taken apart and separated into water and oxygen by a catalase specific to this reaction. The substrate concentration as well as the temperature effect the rate of the chemical reaction. On the other end of the spectrum adding too much of the substrate can have the reverse effect on the reaction. This is also true if the temperature gets outside of a certain range the reaction can then slow down as well. In this experiment we tested the hypothesis that as substrate concentration increases, so will reaction rate because more substrate molecules will be colliding with the enzyme. We also tested the hypothesis that as the temperature increases so will the reaction rate because faster moving substrates bump into each other and bond quicker. We used four different temperatures of enzymes to test how the temperature of the enzyme affects the rate at which the chemical reaction occurs. We also used a variation of substrate concentration ranging from0.1 percent all the way to 0.8 percent. This was done to test how the substrate concentration affects the rate of the chemical reaction. The first experiment demonstrated that when the substrate concentration increases the rate of the chemical reaction also increases. For example, the average rate of the reaction for .1 percent is 1.74ml/min and for .8 it is 55.95ml/min. The results from experiment one support the hypothesis that as the substrate concentration increases the rate of the chemical reaction. The second experiment displayed that when the temperature increases the rate of the chemical reaction decreases. An example of this is at room temperature the average rate of chemical reaction is 55.95ml/min, in contrast at boiling temperatures the average was 1.10ml/min. These results prove that our hypothesis that as the temperature goes up the rate of the chemical reaction goes down.
Materials and Methods
The use of a catalase to speed up the rate of a reaction includes a variety of steps. First the 600 ml beaker was filled to the brim with water. Since some of the water was bound to spill a paper towel was placed under the beaker to absorb the spillage. Next the 10ml graduated cylinder was overfilled with water and then capped off by a person’s finger. They then inverted the graduated cylinder and immersed it into the water careful to not let any air bubbles into the cylinder. This would skew the results and call for a redo of this portion of the experiment. Following the insertion of the cylinder, a U-shaped glass tube was placed into the beaker and maneuvered into the cylinder. On the other end of the glass tube a rubber stopper was placed into the opening of the 50ml Erlenmeyer flask. This was done directly after 10ml of the substrate and 10ml of the catalase were poured into the Erlenmeyer flask. Once everything was added the flask was swirled around as the time it took for air to fill the graduated cylinder was recorded. The substrate concentrations were 0.8 percent, 0.4 percent, 0.2 percent, and 0 percent. The different catalases used consisted of warm(37degrees C),boiled(100degrees C), room temperature (25degrees C), and cold(0degrees C).These concentrations and room temperature were used for both experiments. The data recorded was then put into Microsoft Excel. In Microsoft excel certain programs were run to find the averages, standard deviation, and the p values.
The results for the first experiment are showcased in Table 1. The average and standard deviation for each concentrations reaction rate as well as the results for each of the concentration are shown in the Table 1. An example of this is at 0.4 percent the average rate of the chemical reaction is 26.41ml/min. The standard deviation at the same percent is 18.164. The standard deviation and the average for each concentration was calculated using Microsoft Excel.
The results for the second experiment are displayed in Table 2. The table shows the reaction rate for all of the different temperatures of water. The standard deviation and average are displayed in the Table 2 also. When water is at room temperature the average rate of the chemical reaction is 55.95ml/min and the standard deviation is 39.68. The average and the stand deviation are calculated using Microsoft Excel.
Table 1 is displayed by the graph in Figure 1, and Table 2 is shown graphically in Figure 2. Each of which were graphed used Microsoft Excel.
Table 1: Effect of change in substrate concentration on reaction rate
Substrate concentration Group 1 Group 2 Group 3 Group 4 Group 5 Group 6 Group 7 Group 8 Average Std dev
0.0% 0 0 0 0 0 0 0 0 0.00 0
0.1% 3 0 2.5 2 0 1 2.8 2.6 1.74 1.236282
0.2% 6.5 5 5 6 6 6 5.5 6 5.75 0.534522
0.4% 42.64 15.9 15 27.27 16.67 10 20 63.82 26.41 18.16414
0.8% 63.63 32.03 30 54.45 28.57 27.3 66 145.63 55.95 39.6787
Table 2: Effect of change in temperature on reaction rate in a catalase mediated breakdown of H2O2
Temperature factor Group 1 Group 2 Group 3 Group 4 Group 5 Group 6 Group 7 Group 8 Average Stdev
Cold (0oC) 91.88 24.34 35.19 30 18.75 37.5 37.5 71.51 43.33 25.15
Room Temperature(25oC) 63.63 32.03 30 54.45 28.57 27.3 66 145.62 55.95 39.68
Warm (37oC) 206.9 52.9 120 85.71 200 120 150 173.9 138.68 54.31
Boiled (100oC) 0 3 1.5 0 0 1.33 2.9 0.05 1.10 1.30
Table 3: Analysis of statistical significance for each temperature condition vs room temperature (t-test : two sample assuming equal variances)
temperature comparison used for t-test statistical analysis p values
p value for room temp vs warm temperature 0.00368573
p value room temp vs cold 0.460075553
p value room temp vs boiled 0.001575828
Figure 1. The reaction rate vs substrate concentration
Figure 2. Temperature Factors on Reaction Rate
The experiments that were conducted were meant to test two separate hypotheses. The first hypothesis said that as substrate concentration increases, the reaction rate would also increase. At 0.8 percent the average reaction rate was 55.95ml/min. At 0.1 percent the reaction rate average was 1.74ml/min. These averages support our hypothesis. The second experiment we predicted the higher the temperature the slower the reaction would occur. We also stated that the optimal temperature for the quickest reaction rate would be in-between 25 and 37 degrees Celsius. Boiling catalase had an average reaction rate of 1.10ml/min. When the temperature is 25 degrees Celsius the average is 55.95ml/min and when the temperature is 37 degrees Celsius the average is 138.68ml/min. These results support our hypothesis. It is likely that the reasoning behind the increase of the average reaction rate as the catalase concentration increased was because of the amount of the substrate. For experiment one we can verify that as the substrate concentration increases the rate of the chemical reaction equally increases. In experiment two we can also verify that when the temperature increases too much that the reaction rate will decrease. This most likely occurs because when the temperature crosses a certain point the catalase cannot perform as efficiently.()The temperature can also be too cold and the same outcome occurs. The results shown from both experiments are very important because it shows that a threshold for temperature exist for the optimal performance of a catalase. Some of the possible miscalculations can occur from a variety of reasons including: human error, slight variations in amounts poured, slight variations in temperature of materials used. For future experiments double checking the data recorded as well as making sure the temperature is a little bit more evenly distributed.