Elephant Toothpaste Chemical Reaction Investigation
Science Lab · Grade 7
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Type
science_lab
Pre Lab
Background: Every day, chemical reactions happen all around us — from food cooking in the oven to rust forming on a bicycle. A **chemical reaction** is a process in which substances called reactants are transformed into new substances called products. Scientists look for evidence that a reaction has occurred, such as a color change, gas production, temperature change, or the formation of a precipitate. In today's lab, you will observe a dramatic reaction that produces all of these signs at once!
The reaction you will investigate is called the decomposition of **hydrogen peroxide** (H₂O₂). Hydrogen peroxide is a liquid that slowly breaks apart into water (H₂O) and oxygen gas (O₂) on its own, but this process normally happens very slowly. When a **catalyst** is added, the **reaction rate** — or the speed at which the reaction occurs — increases dramatically. A catalyst is a substance that speeds up a chemical reaction without being used up itself. In this lab, yeast mixed with warm water acts as the catalyst. Yeast contains an enzyme called catalase that causes the hydrogen peroxide to decompose rapidly, releasing a large burst of oxygen gas. This is also an example of **oxidation**, a type of reaction involving oxygen.
The **concentration** of hydrogen peroxide refers to how much hydrogen peroxide is dissolved in a solution — a higher concentration means more hydrogen peroxide molecules are present. Scientists hypothesize that higher concentrations lead to faster reaction rates because there are more reactant molecules available to interact with the catalyst. You will test this idea by comparing reactions using different concentrations of hydrogen peroxide and measuring how quickly and how much foam is produced. As you investigate, think like a scientist: plan your experiment carefully, control your variables, and use your data as **evidence** to support your explanation.
Vocabulary
Term: chemical reaction
Definition: A process in which reactants are chemically changed into new substances called products, often accompanied by observable evidence such as gas production, color change, or heat release
Term: catalyst
Lab Type
Post Lab
Standards
Safety Level
Teacher Notes
Estimated Time
Experiment Design
Research Question
Learning Objectives
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