Summary

In this lab, students will create a supersaturated solution by dissolving borax in boiling water. They will create a snowflake using pipe cleaner to suspend in the solution, which will serve as a nucleation site for crystallization as the solution cools and remains undistributed overnight. This lab gives students an opportunity to experience the exciting crystallization process and become more familiar with an engaging chemistry spectacle!

Grade Level

High, middle or elementary school

Objectives

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

• Describe the meaning of supersaturated solution as well as how to prepare one.
• Differentiate between the vocabulary terms solute, solvent and solution.
• Understand how temperature change can affect the concentration of solute in a solution.

Chemistry Topics

This lab supports students’ understanding of

• Solutions
• Solubility
• Solute
• Solvent
• Concentration
• Saturation
• Nucleation

Time

Teacher Preparation: 20 minutes

Lesson: Day 1 -45 minutes, Day2 – 25 minutes

Materials

Per 2 students:

• 2-3 pipe cleaners (preferably white)
• String
• Scissors
• 2 Pencil or wooden sticks
• Water (~470ml, or 2 cups)
• Hot plate
• 1-600ml beaker
• Beaker tongs/heat-resistant gloves
• 2 Styrofoam cups
• Stirring rod
• Borax (62.7grams, or 6 tbsp.)
• Weighing boat
• Electronic scale

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.
• Exercise caution when using a heat source. Hot plates should be turned off and unplugged as soon as they are no longer needed.
• Long hair should be tied back, and loose clothing secured.

Teacher Notes

• This lab is fun to complete near winter break, or when it first starts to snow.
• Note that this lab can be beneficial for all ages of students, elementary through high school. However, additional adult support will be needed in an elementary classroom. See below for extension ideas when completing this activity with different grade levels.
• In a high school or middle school lab setting, the water should be boiled in 600ml beakers. This will be enough water to make borax solutions for 2 students to use.
• In an elementary classroom, the teacher should use a microwave or electric kettle to boil the water.
• When students create their snowflake, remind them that it should be able to hang inside of the cup or beaker without touching the inside of the container for best results.
• The corresponding student worksheet for this laboratory activity is written for middle and high school students.
• For reference, the ratio needed per student is 3tbsp. of borax for 1cup water, or 31.35g of borax for 235ml of water.
• Photos are shown in the student procedures to help guide students through the lab.
• Note that some students may ask to keep their snowflake, or use it as an ornament. If you allow students to take the snowflake home please caution students about the hazards related to ingestion of Borax (especially if they have pets) – ingestion may cause: gastrointestinal disturbances such as headache nausea, vomiting, abdominal pain, and diarrhea, with delayed effects of skin redness and peeling. The complete safety information for Borax can be found here.
• The photos below show the final snowflake after 6 hours and again after 24 hours:

• Extensions:
  • High School
    • Students can be asked to calculated molarity of the supersaturated Borax solution.
    • Students can be introduced to Solubility charts/graphs as a follow-up.
    • Show this Flinn Video to differentiate between unsaturated, saturated and super saturated solutions.
    • Students can be asked to draw a flow chart to model what is happening during this process on the molecular level.
    • This AACT Solubility animation is a good resource for introducing solubility at the particle level.
    • Students can research Rock Candy, and the process for making it.
    • Many relevant topics from Middle School Chemistry’s unit can be applied in the high school classroom.
  • Middle School:
    • Students can further investigate concentration and solutions through this AACT lab.
    • Students can research Rock Candy, and the process for making it.
    • Show this Flinn Video to differentiate between unsaturated, saturated and super saturated solutions.
    • middleschoolchemistry.com provides an entire unit focused on dissolving solutes in water, many activities and multimedia can be used in combination with this lab.
  • Elementary School:
    • This animated video can help introduce the concept of solute, solvent and solutions to young students.
    • Some basic vocabulary, and a video connection to solutions and the water cycle can be found online.