Effect of Temperature and pH in Catalase Action

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Effect of Temperature and pH in Catalase Action – Lab Report


Inorganic catalysts are often used by chemist in order to speed up the chemical reactions. These inorganic catalysts are not present in living organisms, so instead the living cells of an organism use enzymes. Enzymes speed up chemical reactions as well and they contain the right acids in order to create chemical reactions that are fast enough to support life. It is said that an enzyme functions best within a rather narrow range of temperature and pH ranges. The changes in temperature and pH disrupt the hydrogen which then alters the shape and causes the inactivation of an enzyme. Enzymes protect organisms from harmful products such as Hydrogen Peroxide. Hydrogen peroxide, H202, can seriously damage the cell but with the help of catalase, one of many enzymes of cells, hydrogen peroxide is quickly broken down into water and oxygen. Catalase breaks down hydrogen peroxide at a rate of 40,000,000 molecules per second. Catalase is abundant in the liver of humans and other vertebrates. When the reaction occurs in test tubes, there is layer of foam on the surface of the peroxide. The amount of foamed produced is a measure of catalase activity. The catalase activity is basically the creation of oxygen and water from the broken down hydrogen peroxide (Enzymes Lab). In this lab, different temperatures and pH values will be used in order to determine how much the catalase activity is affected by these changes. The optimal range, which is the most conductive range, will be determined after the labs are completed. The prediction is that there will be a higher catalase activity in the warmer temperature. This means if the reaction takes place in a warm environment, then there will be a higher catalase action than in a cool environment. The other prediction is that there will be a higher catalase activity when pH 7 is added. If pH 7 is added into the substrate, then there will be a higher catalase action than if pH 2 and pH 11 are added.[K1]


The purpose of the first experiment was to find the effect of different temperatures would have on the catalase activity. Each test tube was placed in different temperatures in order to figure out what role does temperature play. The first step into the experiment was to place 5 drops of potato juice into each of the 6 test tubes (1A, 2A, 3A, 1B, 2B, 3B). After the potato juice was added, 5 drops of distilled water were placed into each test tube to combine with the potato juice already in there. Each of the tests tubes where then placed in different temperatures for 5 minutes each. Test tube 1A and 1B were placed in boiling water at a temperature of 90 degrees Celsius. Test tubes 2A and 2B were placed at room temperature at 23 degrees Celsius. The last 2 tubes, test tube 3A and 3B, were placed in crushed ice at 0 degrees Celsius. After 5 minutes passed, Hydrogen peroxide, 3% was added into each test tube in order for a reaction to take place. The catalase action was then measured by the amount of foam produced inside the test tubes.

The purpose of the second experiment was to find out how the addition of different pH values will affect the amount of catalase activity. Different values of pH were added to three different test tubes containing potato juice. The first step in the experiment was to place 10 drops of potato juice into three different test tubes using a medicine dropper. After labeling the three test tubes (1, 2, 3), 10 drops of pH 2 were added into the first test tube. 10 drops of pH 7 were added to the second test tube and 10 drops of pH 11 were added onto the third test tube. Now that we had three different test tubes containing potato juice with different pH values, 5 minutes were given in order for the catalase reaction to take place inside the test tubes. The amount of foam layer each reaction produced was then measured with a metric ruler and recorded.


After completing the first experiment, it was shown in the results that the tubes placed in the crushed ice had a thicker foam layer than the test tubes in room temperature and the ones placed in boiling water (Table 1). As the temperature increased, the catalase reaction was less. The thickness in the foam layer of tubes 1 and 2 (placed in boiling water) was 0 millimeters. The thickness of the foam in tubes 3 and 4 (placed in room temperature) averaged at 3.5 millimeters. The thickness of the foam layer in tubes 5 and 6 (placed in crushed ice) averaged 4 millimeters.

After completing the second experiment, it was seen that the test tube containing potato juice which received the pH 7 had a greater catalase activity than the other test tubes with different pH values (Table 2). The first test tube of potato juice which received the pH 2 was inactivated[K4] and produced no foam. Similar to the first test tube, the third tube with the pH 11 was inactivated as well. The only test tube that received a foam layer was the second one with the pH 7. The second test tube’s foam layer was 7 millimeters.

Temperature and Catalase Action - Table 1


Temperature (Celsius)

Thickness of Foam Layer



0 mm



0 mm



4 mm



3 mm



5 mm



3 mm

Table 1 demonstrates the amount of Foam that was created in the different test tubes which were placed in different temperatures. The thickness of the foam is the measure of how fast the catalase action took place.

pH and Catalase Action - Table 2



Thickness of Foam Layer



0 mm



7 mm



0 mm

Table 2 demonstrates the amount of foam created in the three different test tubes containing potato juice which were combined with different value of pH each.

Discussion: [K5]

After getting the results of the first experiment, it is seen that the results did not match the hypothesis mentioned in the introduction. It was predicted that the tubes in the boiling water would have a greater catalase action but it was wrong. The results demonstrated that the catalase action was greater in the crushed ice and was actually inactivated in the boiling water. There was no foam created inside the boiling water and less foam was seen as the temperature the test tubes were placed in increased.

The results recorded from the second experiment match the hypothesis made in the introduction. The prediction was that the pH 7 added into one of the test tubes would have a greater catalase activity than the pH 2 and pH 11. The pH 7 was the only tube that created foam meaning that it was the only tube that went under catalase activity.


Like mentioned in the introduction, the results show that the enzymes react better in a narrow range of temperature and pH. The catalase action only took place in the range of temperature from 0 degrees Celsius to 23 degrees Celsius. When the temperature reached 90 degrees Celsius, the enzyme was inactivated because the change of temperature disrupts the hydrogen bonding. The hypothesis for the first experiment was not correct, but the hypothesis for the second experiment was. It was shown that enzymes worked better in a narrow range of pH. The change of pH which was caused by the addition of pH 2 and pH 11 inactivated the enzyme and it resulted in no catalase activity taking place in those two beakers only. With the results, it is learned in which ranges of temperature and pH catalase actions take place in.

Works Cited:

Lafortune, T., Briggs, K. 2013 Catalase activity in different tissues at different temperatures and pH values. Science. Vol. 4 Issue 2.[K7]

Laboratory Report 6 – Enzymes. Exercise 6.

[K1]Introduction is real good but the hypothesis should be in if-then format. Take a loo at the lab report notes document to see how to do that.

[K2]Methods are good


[K4]This statement is more appropriate in the discussion


[K6]Everything here could have been incorporated into the discussion section.

[K7]In order to use this as a source you need to mention it somewhere in the report.