Effects of pH on Enzyme Activity

Problem: To what extent does pH affect enzyme activity rate?

Research: Please research the following terms: enzymes, catalyst, catalase, hydrogen peroxide,

Hypothesis: H1



Materials: hydrogen peroxide, 50 ml beaker, 250 ml beaker, graduated cylinder, distilled water, filter paper disks, forceps from dissecting kits, stopwatch


  1. Cut a small slice of potato to take to your lab table.
  2. Pour 5 ml of hydrogen peroxide into a 50 ml beaker.
  3. Pour 45 ml of distilled water into the beaker to make a total liquid volume of 50 ml.
  4. Take the temperature of the mixture in degrees C and record it in the data table
  5. Dip a disk of filter paper (cut with a hole punch) into the freshly cut potato's wet liquid until it is soaked completely.
  6. When the timer says go, force the filter paper using the forceps to the bottom of the 50 ml beaker with peroxide and water.
  7. Record the number of seconds it takes for the paper to reach the top.
  8. Repeat steps 5 through 7 four more times so that you have 5 trials at the room temperature.
  9. Change the temperature of the solution by placing the 50 ml beaker with the solution into a 250 ml beaker with ice.
  10. Allow the smaller beaker and solution to sit in the ice until it drops 4 degrees C. Record the new temperature in the data table.
  11. Repeat steps 5 through 7 at the new temperature for 5 trials.
  12. Record and graph the data.
  13. Calculate the averages.
  14. Calculate the difference between the groups.
  15. Do a ttest to see if the difference you got was significant.
  16. If you have time, repeat the above procedure by heating the solution in a 250 ml beaker hot water bath 8 degrees from the low.

Data Table an Graph:


original solution temp. in deg. C


time to reach surface (sec)

temp. after cooling in deg .C


time to reach surface (sec)

temp after heating 8 degree C


time to reach surface (se)

______ XXXXX  
ttest = p =
______ XXXXX  
to Reach

Temperature on Enzyme Activity Levels


temperature deg. C