Elephant Toothpaste Lab Worksheet
Middle / High School Chemistry Lab
Name: Date: Period:
Lab Investigation: Elephant Toothpaste & Reactions
Exploring Catalyzed Decomposition, Conservation of Mass & Energy Changes
Safety First: Goggles & Gloves Required
Driving Question
How can we prove that a chemical reaction has occurred when hydrogen peroxide (\(\text{H}_2\text{O}_2\)) interacts with a yeast catalyst?
Part 1: Pre-Lab Hypothesis & Predictions
1. Prediction: Read the lab procedure. What do you predict will happen when the yeast mixture is added to the hydrogen peroxide and dish soap solution?
2. Observable Criteria: Based on your knowledge of physical and chemical changes, what specific evidence will you look for to prove a chemical change has taken place?
Part 2: Qualitative Data & Observations
Record physical states, sensory details, and temperatures
| Substance / Phase | Physical Properties Before Reaction
(Color, state of matter, clarity, temperature) | Observations During & After Reaction
(What do you see, feel, smell, and hear?) |
| --- | --- | --- |
| Hydrogen Peroxide (\(\text{H}_2\text{O}_2\)) + Soap | | |
| Yeast + Warm Water Mixture | | |
| The Resulting Foam | (Leave blank before reaction) | |
Thermal Energy Check
Carefully touch the outside of the reaction vessel (bottle) during the peak of foam eruption. What do you notice about the temperature change?
Elephant Toothpaste Chemistry Investigation Page 1 of 2 • Continue to Analysis & Conservation of Mass →
Elephant Toothpaste Lab: Post-Lab Analysis & Modeling
Student Name:
Part 3: Analysis & Molecular Modeling
Balanced Decomposition Equation
\( 2\text{H}_2\text{O}_2 \xrightarrow{\text{Catalyst (Yeast)}} 2\text{H}_2\text{O} + \text{O}_2\uparrow \)
+ Thermal Energy (Heat Released)
Identify the Chemical Components:
What are the reactants in this experiment?
What are the products in this experiment?
What role did the yeast play in the reaction?
Count the Atoms (Law of Conservation of Mass): Reactants side vs. Products side
| Element | Total Atoms on Reactant Side
2 H₂O₂ | Total Atoms on Product Side
2 H₂O + 1 O₂ |
| --- | --- | --- |
| Hydrogen (H) | | |
| Oxygen (O) | | |
Did the total number of atoms change? Explain how this demonstrates the Law of Conservation of Mass:
Part 4: Conclusion & Evidence
1. Thermal Energy Classification: Was this reaction endothermic (absorbed heat) or exothermic (released heat)? Use your laboratory observations to justify your answer:
2. Evidence of Chemical Change: Provide two concrete pieces of evidence from this lab proving that a chemical reaction occurred rather than just a physical mixture:
Evidence 1:
Evidence 2:
Elephant Toothpaste Chemistry Investigation Page 2 of 2 • Assessment Ready
Elephant Toothpaste Reaction Slides
Chemistry Lab Investigation
Physical vs. Chemical Changes
Elephant Toothpaste:
Catalyzed Reactions & Energy
Driving Question
How can we prove that a chemical reaction has occurred when hydrogen peroxide interacts with a yeast catalyst?
Investigation & Molecular Modeling Guide Slide 1 of 6
The Chemical Equation & Catalyst
Chemical Decomposition
Decomposition Equation
\( 2\text{H}_2\text{O}_2 \xrightarrow{\text{Catalyst}} 2\text{H}_2\text{O} + \text{O}_2 \)
Reactant: Liquid Hydrogen Peroxide (\(\text{H}_2\text{O}_2\))
Products: Liquid Water (\(\text{H}_2\text{O}\)) & Oxygen Gas (\(\text{O}_2\))
What Does Yeast Do?
Yeast contains catalase, a natural enzyme that acts as a catalyst.
A catalyst speeds up the reaction without being consumed or permanently altered.
Dish soap traps the escaping \(\text{O}_2\) gas, creating millions of foamy bubbles!
Key Point: Catalysts are facilitators, not chemical reactants.
Part 1 Pre-Lab Hypothesis Slide 2 of 6
Lab Safety & Procedure Checklist
Safety First
PPE Required
Splash goggles and nitrile gloves must stay on throughout the entire experiment and cleanup.
Contain Eruption
Position your bottle squarely in the center of the spill tray before pouring your yeast mixture.
Safe Touch
Touch only the outside of the plastic bottle. Avoid touching hot foam until cooled and instructed.
Ready to combine? Add warm yeast solution in one smooth pour and step back immediately! Slide 3 of 6
Active Observation: What to Record
Data Table Focus
Visual & Auditory Clues
Gas Bubbles: Rapid column of foam emerging from bottle mouth.
Sound: Listen closely for hissing, sizzling, and crackling gas release.
Texture: Density, height, and expansion of the soap-foam matrix.
Thermal & State Observations
Bottle Heat: Feel the bottle exterior at peak reaction. Is it hot or cold?
Vapor / Steam: Look for thermal water vapor rising from the hot foam plume.
Record Details: Write precise descriptive words into your Part 2 Data Table.
Fill out Part 2 Data Table on Worksheet Page 1 Slide 4 of 6
