Simplified Catalase Lab

Question:

Chose one question to investigate:

1. What effect will decreasing the substrate (H₂O₂) concentration by 50% have on the reaction rate?
2. What effect will decreasing the enzyme (catalase) concentration by 50% have on the reaction rate?

Background:

"A catalyst ... increases the rate of the [chemical] reaction without being used up in the process. Catalase is an enzyme, a biological (organic) catalyst. Hydrogen peroxide (H₂O₂) is a poisonous byproduct of metabolism that can damage cells if it is not removed. Catalase is an enzyme that speeds up the breakdown of hydrogen peroxide into H₂O and O₂." Source: Genevieve Nelson. Access Excellence Catalase Lab. On-line. © The National Health Museum.

We will be using a potato extract as a source of catalase. You will record the time it takes a catalase-soaked paper disk to rise when placed in H₂O₂. The disk will rise from the added buoyancy of O₂ bubbles clinging to it. We will use this time as a proxy measurement for reaction rate.

Hypotheses (predictions):

A prediction using the "If __ then ___, because ____" format is provided by the student.

Equipment:

10 ml graduated cylinder (2) test tubes petri dishes forceps

5 ml catalase solution (potato extract) in ice bath. hydrogen peroxide (H2O2). 3% standard dilution. 6 mm diameter filter paper discs

Procedure for Measuring Catalase Activity:

Contamination is an issue with this lab. Do not use your fingers. Use the forceps and wash the forceps after touching the catalase or H₂O₂ solution.

1. Fill a test tube with _____ ml of fresh H₂O₂ solution.
2. Use the forceps to place a paper disc in the enzyme solution for _____ seconds.
3. Use the forceps to place the disc on a paper towel for ____ seconds to drain off the excess enzyme solution.
4. Use the forceps to place the disc at the bottom of the H₂O₂ solution.
5. Measure and record the time it takes the disk to rise to the surface.
6. Repeated trails: repeat steps 1 through 5 ______ times.

Procedure for Creating Catalase or Substrate Dilutions:

Student provided.

Data Tables

Student provided.

Conclusions

Student provided.