Enzyme Catalysis
Sections
1. Activity A: Decomposition of H2O2 by Catalase
2. Activity A: Predictions
3. Activity A: Results
4. Catalase Reaction and Titration: What to expect
5. Activity B: Determining Baseline Solution
6. Activity C: Uncatalyzed Decomposition
7. Activity D: Catalyzed Decomposition
8. Review
Sections
1. Activity A: Decomposition of H2O2 by Catalase
2. Activity A: Predictions
3. Activity A: Results
4. Catalase Reaction and Titration: What to expect
5. Activity B: Determining Baseline Solution
6. Activity C: Uncatalyzed Decomposition
7. Activity D: Catalyzed Decomposition
8. Review
1. Activity A: Decomposition of H2O2 by Catalase
Hydrogen peroxide (H2O2) naturally decomposes into water and oxygen gas on its own.
The enzyme catalase speeds up this process significantly.
The result is a bubling effect, resembling the fizz of a carbonated beverage.
This fizz is the oxygen gas being released quickly as the hydrogen peroxide breaks down.
Click the Next Section button to enter your predictions before beginning Activity A.
Click the Next Section button to enter your predictions before beginning Activity A.
2. Activity A: Predictions
Goals Answer all questions
Submit your answers
| What do you expect to see when the H2O2 is combined with catalase?
What do you expect to see when the H2O2 is combined with boiled catalase?
What do you expect to see when the H2O2 is mixed with a potato or liver sample?
|
3. Activity A: Results
Goals Answer all questions
Submit your answers
| What did you see when the H2O2 was combined with catalase?
What did you see when the H2O2 was combined with boiled catalase?
What did you see when the H2O2 was mixed with a potato or liver sample?
|
4. Catalase Reaction and Titration: What to expect
Goals Watch the titration experiment
| As you saw in Activity A,
the catalase will react with hydrogen peroxide to speed up decomposition into water and oxygen gas.
To stop the reaction, hydrogen sulfide is added.
Hydrogen sulfide is a strong acid, capable of denaturing the enzyme.
It stops the enzyme just like boiling did in Activity A.
Both heat and acids can denature enzymes to make them inactive.
Once the enzyme has been denatured and the reaction is stopped, potassium permanganate is used to see how much hydrogen peroxide remains. Potassium permanganate is dark purple, but when it makes contact with hydrogen peroxide, it gets reduced and becomes colorless. Watch the video below to see what to expect. loading... When titrating, try to add only one drop at a time so that you get an accurate reading.
Keep swirling the reaction vessel so that the reactants mix well.
Once the potassium permanganate no longer becomes colorless while swirling the vessel,
you know you have reacted with all the hydrogen peroxide.
By adding the potassium permanganate one drop at a time,
you can determine the volume that was needed to react with all of the hydrogen peroxide left.
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5. Activity B: Determining Baseline Solution
Instructions Enter your titration volumes. Goals Enter titration volumes.
Check calculations.
|
Enter your change in volume as the baseline reading.
Baseline (mL) |
6. Activity C: Uncatalyzed Decomposition
Instructions Enter your titration volumes. Goals Enter titration volumes.
Check calculations.
|
The uncatalyzed rate of decomposition is the Baseline
from Activity B minus the Change in Volume in the table above.
Calculate the uncatalyzed rate and enter it below.
Uncatalyzed decomposition (mL) |
7. Activity D: Catalyzed Decomposition
8. Review
Goals Answer all questions
Submit your answers
| Hydrogen peroxide decomposes into _____.
What catalyzed the reaction?
What was the substrate in the reaction?
What stopped the reaction?
Why did the molecule in the previous question stop the reaction?
What was used to measure the hydrogen peroxide left in solution after the reaction was stopped?
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9. Lesson Done
Instructions You have completed the lesson. You may scroll up to review the lesson. |
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