MnSTEP Teaching Activity Collection > MnSTEP Activities > Lab Investigation Mixture Separation

Lab Investigation Mixture Separation

John Ristvedt, CGB High School, Graceville, MN, Modern Chemistry Book
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Summary

This investigation is to help reinforce the idea that a mixture can be taken apart by physical means. It will be set up as a contest in which students will have 3 hours of class to separate as much pure substance as they can. These will be broken into percentages based on purity and the amount they have been able to separate. There is no procedure written so students have a completely open and inquiry based activity.

Learning Goals

The difference between a mixture and a compound
Some of the physical properties of the substances
Practice in writing procedures that others would be able to follow
How to use evaporation baths correctly and other lab equipment.
Vocabulary - The difference between a compound and a mixture.

Context for Use

This is to be used in the beginning of the year to help the students become familiar with the different lab equipment.

Student level 9-12

The students should be allowed any equipment within reason as well has have an understanding of the equipment before using it. Generally this is coupled with a lab equipment quiz in the chapter.

Time needed is about 3 days of 50min class periods for best results.

Skills the students should know are the different types of equipment in the lab and lab safety.

This would be easy to adapt to other activity settings

Subject: Chemistry:General Chemistry:Mixtures, Solutions, & Compounds
Resource Type: Activities:Lab Activity
Grade Level: High School (9-12), Middle (6-8)

Description and Teaching Materials

This lesson may be met with some whining because it is a little difficult for the students to imagine different ways to separate the different materials; however, it is a good practice toward student based learning. The students will receive the lab report below that they need to separate the mixture. I will also give them a list of materials that will be available to them. They have the night to think about how they will separate the solution through the use of different physical processes. Their main objective is to separate as much of the pure substances as possible.
Set up the lab using the materials listed below for the students before they arrive. They will also be working in pairs so have a sample of the mixture in test tubes. They are to take one test tube and begin working immediately. Walk around and observe what is going on. Answer most of the questions with the phrase, "maybe you can think of a way to do that." Once students have as much of the substances sorted out then take percentages of the total amount and add them together. The group with the highest percentage wins and will get a treat of their choice. Collect all of the other labs and check them over.

Materials needed for the lesson:
- Lab Investigation Mixture Separation (link)
- Lab Investigation Mixture Separation Check (link)
- 60g of mixture made of
o 15g of Sand
o 15g of Salt
o 15g of Iron Filings
o 15g of Poppy Seeds
- At the labs possible equipment
o Petri Dishes
o Wells
o Micro funnels
o Tape
- At the center table
o Roll of Cellophane
o Test tubes
o Rubber Stoppers
o Roll of Al Foil
o Wooden splints
o Plastic Forks
o Pipets
o Filter Funnel
o Filter Paper
o Forceps
o Tissue Paper
o Paper Towels
o Straws
o Paper Clips
o Distilled Water
o Magnets

The closure to this activity is to talk to the students and find out what they did. Have them share a brief version what they did. Ask how the different methods arrived at the same goal. Can students think of other ways of doing it? What did they learn? The most important part to the students is who did the best, although this is not what is the most important overall. The lesson plan I have (Microsoft Word 36kB Aug13 08) The student's lab (Microsoft Word 27kB Aug13 08) The Student's Lab Answers (Microsoft Word 29kB Aug13 08) An excel sheet created with examples of how to determine the best sample (Excel 51kB Aug13 08)

Teaching Notes and Tips

When doing the total, mass it first and then look at it. If they are over 15g then they have some impurity or it is still wet. This hurts the purity percentage.
Allow students to expand the list within reason and walk around and observe them in action; this gives you a feel for how they will be in lab and how they are using the equipment.

Assessment

Students are graded on the answer to the Conclusions and Questions as well as their procedure on how they accomplished the separation procedure. The underlying question when looking at the procedure is if I can replicate it.

Standards

II.A.9

Physical Science. Structure of Matter. The student will differentiate between an element and compound

1.B.1-4

Students designing an experiment in scientific inquiry

References and Resources

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