Summary

In this lab, students will be challenged to create a density column, consisting of three distinct layers of sugar-water solution. This is an inquiry lab, where the students must apply their understanding of density and concentration in order to devise a successful plan for creating the column correctly.

Grade Level

High School

NGSS Alignment

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

• Scientific and Engineering Practices:
  • Using Mathematics and Computational Thinking
  • Analyzing and Interpreting Data

Objectives

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

• Design and create a density column using three different concentrations of sugar-water solution.
• Explain the concept of density.
• Use inquiry to successful develop and carryout a lab procedure.

Chemistry Topics

This lab supports students’ understanding of

• Density
• Solutions
• Concentration

Time

Teacher Preparation: 30 minutes

Lesson: 45 minutes

Materials (per group)

• Sugar
• Food Coloring
• Water
• Large Test Tube
• Pipette or Eye Dropper
• Beakers
• Metal Scoop
• Balance

Safety

• Always wear safety goggles when handling chemicals in the lab.
• 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.
• Food coloring stains skin and clothes, so precautions should be made.
• Do not consume lab solutions, even if they’re otherwise edible products.
• Food in the lab should be considered a chemical not for consumption.

Teacher Notes

• The students must show the final product to the teacher, and explain how much water and sugar are in each level for full credit.
• Sometimes I give bonus to the first three groups to successfully finish.
• Due to its cost, food coloring cannot be its own layer. It should only be used to differentiate between layers.Also, pure sugar cannot be a layer. All layers must be solutions.
• Direct students to slowly add one layer on top of another.If added too fast, the layers will mix.

• If there are not enough balances, the students can substitute the unit “scoop” for grams/mass.Have the class agree on the size of a “scoop” (typically a pea-sized amount on the tip of a scoopula).
• In order to be successful students must create 3 solutions of different densities. Ideally, the students would use the same amount of water, and three different amounts of sugar. Food coloring is used just to distinguish the different layers. A layer can be clear if desired. The students should add the most dense solution to the tube first, then slowly add the next solution (second dense solution) so the layers won’t mix. Then add the third.
• The color combination shown in the test tube on the student sheet can be modified based on the availability of food coloring.
• Sample student test tube is shown in the photograph.
• All chemicals can be safely disposed of in the sink.