NAME :
CLASS : DBT 4A
DATE SUBMITTED : 14 AUG 2015

EXPERIMENT 4: CATALASE AND THE DECOMPOSITION OF H2O2 (VIRTUAL)


PROCEDURE

1. Fill the beaker with water and 5ml of hydrogen peroxide.
2. Pipette 1ml of catalase enzyme into the beaker.
3. After 10 seconds, add sulfuric acid into the beaker.
4. Using titration method, check the presence of hydrogen peroxide in beaker.
5. Fill the burette with 5ml of potassium permanganate ( KMnO4).
6. Add KMnO4 drop by drop into the beaker until the H2O2 become purple color.
7. Record the data.
8. Repeat the step 1 until step 7 for 30, 60, 90, 120 and 180 seconds.

RESULTS
Determination of catalase activity

Time (s) 10 30 60 90 120 180
Initial reading of KMnO4 (ml)
5
5
5
5
5
5
Final reading of KMnO4 (ml)
0.5
1.5
3
4
4.5
4.9
Amount of H2O2 that reacts with KMnO4 (ml)
4.5
3.5
2
1
0.5
0.1
Amount of H2O2 that was broken down by catalase
0.5
1.5
3
4
4.5
4.9
Amount of KMnO4 (ml) used
4.5
3.5
2
1
0.5
0.1
Rate determination
Time intervals (s) 0 - 10 10 - 30 30 - 60 60 - 90 90 -120 120 - 180
Rate (ml/s) 0.45
0.18 0.07 0.03 0.02 1.67 X 10-3

Calculation :
Amount of H2O2 that reacts with KMnO4 (ml) = Rate (ml/s)
Time

1) 4.5ml
10 - 0
= 0.45 ml/s

Graph





DISCUSSION

The purpose of this experiment is to study the rate of enzyme catalase which involves in hydrolyzing process. This means that to determine the time taken for the catalase to breaks down hydrogen peroxide into water and oxygen. Amount of hydrogen peroxide that was broken down by catalase determined by the production of the bubbles. While the amount of remaining hydrogen peroxide measured by the help of potassium permanganate. Which means that amount of potassium permanganate needed to change the color of the catalase solution to purple is the remaining amount of hydrogen peroxide. Substrate of this experiment is the hydrogen peroxide while the products are water and oxygen gas. When the catalase enzyme is added to the beaker which contains water and hydrogen peroxide bubbling in the solution can be observed. The production of bubbles shows the process of breaking down of hydrogen peroxide into water and oxygen gas and it is the appearance of products. For an instance, 0.5ml of hydrogen peroxide was broken down by catalase enzyme in 10 seconds. Potassium permanganate was used to measure the disappearance of hydrogen peroxide by titration method. Potassium permanganate added to the hydrogen peroxide solution drop by drop until color changes occur. The solution turns into purple color which indicate the disappearance of the hydrogen peroxide. For an example, 4.5ml of potassium permanganate is used to change the color of solution into purple. The break down of hydrogen peroxide into water and oxygen gas by catalase can be summarized as :
Catalase
2 H2O2 2 H2O + O2

Potassium permanganate is an oxidizing agent. Thus, it is reduced by hydrogen peroxide to a clear solution. But as soon as the hydrogen peroxide is gone the intense purple color of the permanganate will be visible. The equation of this reaction is :
5 H2O2 + 2MnO4- + 6H+ = 5O2 + 2Mn2+ + 8H2O