Summary

In this lab, students create a mixture of oil, water and food coloring, and then add an Alka-Seltzer tablet, to create a homemade lava lamp. Student will record their observations during each step of the process and answer follow-up questions about the chemical and physical changes that took place.

Grade Level

Elementary school

NGSS Alignment

This lab will help prepare your students to meet the performance expectations in the following standards:

• 2-PS1-1: Plan and conduct an investigation to describe and classify different kinds of materials by their observable properties.
• MS-PS1-2: Analyze and interpret data on the properties of substances before and after the substances interact to determine if a chemical reaction has occurred.
• 5-PS1-4: Conduct an investigation to determine whether the mixing of two or more substances results in new substances.

Objectives

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

• identify chemical changes.
• identify physical changes.
• compare the densities of different substances.

Chemistry Topics

This lesson supports students’ understanding of

• Mixtures
• Observations
• Chemical change
• Physical change

Time

Teacher Preparation: 15 minutes
Lesson: 40 minutes

Materials

For each group:

• Water (approximately 1/2 cup)
• 1 Mason jar with lid, or reusable plastic bottle
• Vegetable oil (approximately 1 cup)
• Food coloring
• 1 Alka-Seltzer tablet
• Dish soap

Safety

• Always wear safety goggles when working with chemicals in a laboratory setting.
• Students should wash their hands thoroughly before leaving the lab.
• When students complete the lab, instruct them how to clean up their materials and dispose of any chemicals.

Teacher Notes

• This lab was inspired by and adapted from the high school version, The Lovely Lava Lamp.
• Place students in pairs or groups of 3.
• Have a large container at the front of the room to discard the used vegetable oil.
• It is recommended that the teacher practice this before completing the lab with their students.
• A video has been included to help prepare for teacher expectations.

Procedure

1. Pour water into the plastic bottle until it is approximately 1/3 of the way full. (The exact measurement doesn’t matter)
2. Add vegetable oil to the bottle, use about double the amount of oil as you did water, fill it close to the top (again, the exact amount doesn’t matter)
3. Wait until the oil and water have separated. Record your observations in the data table.
4. Add 10-15 drops of food coloring to the bottle.
5. Watch as the food coloring falls through the oil (it may or may not mix with the water yet). Record your observations in the data table.



6. Break an Alka-Seltzer tablet into five or six pieces and drop the pieces into the bottle. Record your observations in the data table.
7. Clean up: After the reaction has stopped, slowly pour most of the oil into the designated container. Try not to pour in any colored water. Add a squirt of dish soap to the remaining oil and water in your bottle, swish it around to mix, and dump the resulting solution down the drain. Put the empty bottle in the trash, NOT the recycling bin.