Chose one question to investigate:
- What effect will decreasing the substrate (H2O2) concentration by 50% have on the reaction rate?
- What effect will decreasing the enzyme (catalase) concentration by 50% have on the reaction rate?
Source: Genevieve Nelson. Access Excellence Catalase Lab. On-line. © The National Health Museum. Accessed 3/20/2007
- "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."
Mr. Rick says:
- 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.
A prediction using the "If __ then ___, because ____" format is provided by the student.
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.
The student will create a procedure to:
- Measure the baseline catalase activity (undiluted solution).
- Dilute the catalase or substrate.
- Measure the catalase activity using the diluted solutions.
Generic Procedure for Measuring Catalase Activity:
- Fill a test tube with _____ ml of fresh H2O2 solution.
- Use the forceps to place a paper disc in the enzyme solution for _____ seconds.
- Use the forceps to place the disc on a paper towel for ____ seconds to drain off the excess enzyme solution.
- Use the forceps to place the disc at the bottom of the H2O2 solution.
- Measure and record the time it takes the disk to rise to the surface.
- Repeated trails: repeat steps 1 through 5 ______ times.