In this lab, students will be given a test tube with four substances with unknown identities to the students. They will mix the substances in the test tube and recreate the original four layers through chemical and physical means.
By the end of this lesson, students will
- collect quantitative and qualitative data and use chemical and physical properties to separate a mixture.
This lesson supports students’ understanding of
- Chemical change
- Physical change
- Separating mixtures
Teacher Preparation: 30 minutes
Lesson: 2 class periods
For each group:
- Test tube with four (unknown) layers
- Empty test tube
- Hot plate
- Stirring rod
- Other materials as students request
- Always wear safety goggles when working 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.
- Students should exercise caution when using a heat source. Hot plates should be turned off and unplugged as soon as they are no longer needed.
- The following substances are possible layers, but other substances can be substituted: sodium chloride, iron filings, sand, and wood shavings.
- I do not tell the students what the substances are.
- This is a relatively simple lab to prepare. The lab is inquiry and students can be given very little prompt to successfully separate the mixture and return it to its original state within the test tube.
For the Student
- Obtain a test tube. It should have four distinct layers.
- Record qualitative and quantitative observations.
- Mix the substances by holding the stopper with your thumb and tilt the test tube back and forth.
- Record additional observations after mixing.
- Now separate the mixture and recreate the original test tube. Identify whether the process used to separate a particular layer was based on a physical or chemical property.
- Identify the substances in the test tube.
Did you recreate the test tube using chemical changes, physical changes, or both kinds of changes?
Connections to Standards
Missouri Content Standards
1.1.A.a, 1.1.A.b, 7.1.A.a, 7.1.A.b, 7.1.A.c, 7.1.A.g, 7.1.B.a, 7.1.B.c, 7.1.C.b, 7.1.C.c, 7.1.C.d, 7.1.D.a