Potato Catalase Hydrogen Peroxide Decomposition

Students observe how the enzyme catalase in potato accelerates the decomposition of hydrogen peroxide into water and oxygen. By comparing room-temperature, boiled, and frozen potato, they explore how temperature affects enzyme activity.

1. Gather a potato, hydrogen peroxide solution, a knife, heat-safe cup or beaker, and a way to chill and boil samples.
2. Cut the potato into three equal pieces: one for room temperature, one to freeze for at least 30 minutes, and one to boil for at least 5 minutes; cool the boiled piece to room temperature before use.
3. Chop and gently mash about 1 tablespoon of the room-temperature potato in a small cup to increase surface area.
4. Add enough hydrogen peroxide to fully cover the potato and watch for bubble formation.
5. Repeat the mash-and-add-peroxide steps for the boiled sample and for the frozen sample (allow the frozen piece to be chopped quickly while still cold).
6. Compare bubble production across the three conditions and note which sample shows the fastest and slowest reactions.
7. Record qualitative observations (bubble height, speed, duration) and relate them to enzyme activity.

Enzyme Potato Experiment - Professor Revell:

Potato Catalyzed H2O2 Decomposition - North Carolina School of Science and Mathematics:

📄 Catalase and Hydrogen Peroxide Experiment - Education.com: https://www.education.com/activity/article/activator/

• Test additional temperatures (refrigerated vs warm water bath) to build a simple enzyme activity curve.
• Compare different plant sources of catalase (apple, liver substitute like spinach leaves) with equal masses.
• Vary hydrogen peroxide concentration using store dilutions to explore substrate concentration effects.
• Compare different particle sizes of potato by finely dividing some.

• Wear eye protection; hydrogen peroxide can irritate eyes and skin.
• Use only low-concentration household hydrogen peroxide (about 3%); higher concentrations require additional precautions and should be avoided in classrooms.
• Handle knives and hot items (boiling water, hot potato) carefully; use tongs or heat-resistant gloves.
• Do not ingest any materials; treat all samples as not food and dispose of mixtures in the sink with plenty of water.
• Clean all surfaces and wash hands after the activity.

• What gas forms the bubbles you observe, and how is it produced? (Oxygen gas, produced when catalase catalyzes the breakdown of hydrogen peroxide into water and oxygen.)
• Why did the boiled potato show little or no bubbling? (Heat denatured catalase, changing its shape so it no longer functions.)
• Why did the frozen potato react more slowly than the room-temperature sample? (Lower temperature reduces molecular motion, slowing enzyme-substrate collisions and reaction rate.)
• How would changing the amount of potato affect the reaction? (More catalase increases the number of active sites, generally increasing the rate and bubble volume up to other limiting factors.)
• If two room-temperature trials gave different bubbling, what variables might explain the difference? (Differences in potato surface area, mass, peroxide volume or freshness, or sample temperature and mixing.)