Summary

In this demonstration, students will identify factors that indicate a chemical change has occurred while observing the production of giant toothpaste. This reaction uses simpler materials than those that are often used in the typical high school version of the Elephant’s toothpaste demonstration.

Grade Level

Elementary and Middle School

Objectives

By the end of this demonstration, students should be able to

• Determine indicators that help identify a chemical change.
• Identify a chemical change.
• Record Observations.

Chemistry Topics

This demonstration supports students’ understanding of

• Chemical Reactions
• Chemical changes
• Indicators of Chemical Change
• Energy
• Exothermic & Endothermic

Time

Teacher Preparation: 10 minutes

Lesson: 15 minutes

Materials

• 12 oz. Plastic bottle
• ½ Cup of 3% Hydrogen peroxide
• Liquid dish soap
• 1 package of dry yeast (1/4 ounce)
• 3 tbsp. of warm water
• Plastic or glass cup/bowl
• Stir stick
• Baking sheet/pan to collect the foam produced
• Funnel
• Food coloring
• Measuring spoons & cups

Safety

• Always wear safety goggles when handling chemicals in the lab.
• Students should wear proper safety gear during chemistry demonstrations. Safety goggles and lab apron are required.
• Gloves are recommended during this demonstration.

Teacher Notes

• Factors that indicate a chemical change are: color change, formation of a gas, change of temperature, formation of a solid (precipitate). This lab will demonstrate at least 2 of these.
• I suggest pre-measuring the ingredients so that the demonstration moves along quickly.
• As an option, you may want to conduct two demonstrations, one using a 20 oz. bottle and then another using a 2-liter bottle. You could easily spiral in a quick memo about pressure and how it’s affected by the circumference of a vessel (if you’ve already covered the human body system, more specifically the cardiovascular system).
• You could make a real-world connection to the toothpaste that we use and have them identify chemical changes they’ve noticed while using it.
• If you have access to 6% hydrogen peroxide you could to a comparison of rate of reaction based on difference in concentration.
• Procedure:
  1. Place a large pan or tray on a table.
  2. Stand the bottle upright in the middle of the tray.
  3. Measure 1/2 cup of 3% hydrogen peroxide.
  4. Place a funnel in the mouth of the empty bottle.
  5. Carefully add the hydrogen peroxide to the bottle.
  6. Add a few drops of food coloring to the bottle and swirl.
  7. Add a few drops of dish soap to the mixture. Swirl again.
  8. In the plastic cup or bowl, add 1 package of dry yeast (1/4 ounce).
  9. Measure 3 tbsp. of warm water, and add to the dry yeast. Use your stir stick to mix the water and yeast.
  10. Again, using the funnel, add the water-yeast mixture to the bottle.
  11. Immediately remove the funnel, and observe the reaction!