This demonstration investigates how the pH of a solution affects the activity of the enzyme catalase, obtained from yeast. The enzyme breaks down hydrogen peroxide into water and oxygen, and the rate of reaction is measured by the height of foam produced as oxygen gas is trapped by detergent.

1. Label five test tubes with the pH values 1, 4, 7, 8, and 12.
2. Add 5 ml of hydrogen peroxide to each test tube.
3. Adjust the pH of each tube by adding suitable acid or alkali solutions to reach the target pH levels.
4. Add a few drops of universal indicator to confirm the pH of each tube.
5. Add a few drops of detergent to each tube to trap oxygen gas as foam.
6. Add 1 ml of yeast solution (a source of catalase enzyme) to each tube.
7. Allow the reactions to proceed for 5 minutes at room temperature.
8. Measure and record the height of foam produced in each tube as an indicator of enzyme activity.

How pH effects enzyme activity - Milne’s Science Tech:

• Test additional pH values between 5 and 9 to more precisely determine the optimum pH.
• Use catalase from different sources such as potato or liver.
• Repeat the experiment at different temperatures to see combined effects of pH and temperature.

• Wear safety goggles and gloves when handling acids, alkalis, and hydrogen peroxide.
• Avoid skin contact with hydrogen peroxide and strong pH solutions.
• Work in a well-ventilated area or fume hood if possible.
• Dispose of chemical mixtures safely according to local regulations.

• What is the function of catalase in this experiment? (It breaks down hydrogen peroxide into water and oxygen.)
• Why is detergent added to the test tubes? (It traps the oxygen gas released, forming foam that can be measured.)
• At which pH was enzyme activity highest? (The highest foam production occurred at pH 8, suggesting this is near the enzyme’s optimum pH.)
• Why does enzyme activity decrease at very high or low pH values? (Extreme pH levels alter the enzyme’s shape and denature the active site, reducing activity.)