Solutions: Solubility and Miscibility

Tracy Hegarty, New York Mills High School, New York Mills, MN, based on demonstration from 75 Easy Chemistry Demonstrations, Solutions: Solids and Liquids, p. 27

Summary

In this lab, students will investigate the solubility and miscibility of several substances using water as the solvent. Students will need to describe what is happening at the molecular level for each case. Lastly, students will be asked to predict the result of both a solid and a liquid added to the solvent.

Learning Goals

Concepts & content:
1. Predicting results (hypothesis formation)
2. Interpreting results.
3. Explaining results in terms of intermolecular forces.
Skills
1. Safe laboratory procedure/behavior
2. Observing and recording data
3. Writing a lab report
Key concepts:
1. "Likes dissolve likes".
2. Solids that dissolve in liquids are soluble.
3. Solids that do not dissolve liquids are insoluble.
4. Liquids that mix with other liquids are miscible.
5. Liquids that do not dissolve are immiscible.
Vocabulary:
1. soluble
2. insoluble
3. miscible
4. immiscible
5. polar substance
6. non-polar substance
7. intermolecular forces

Context for Use

This activity is designed for high school chemistry classes. It is to be used during the study of solutions when solubility and miscibility have been introduced. One class period would be plenty of time for introduction of lab and completion of an informal lab report. Use standard laboratory precautions.
Subject: Chemistry
Resource Type: Lab Activity
Grade Level: High School (9-12)

Description and Teaching Materials

Introduce lab by having students give examples of what they think are soluble, insoluble, miscible, and immiscible substances. Students should work in groups of three. Materials can be dispensed from a central location. Materials: test tube rack, nine test tubes, water, salt, sugar, oil, vinegar, alcohol, iron filings, sulfur, glycerol, diluted food coloring (with water), dish soap. Students will add four solids to four test tubes half-filled with water. (Students should first predict solubility of each). Then students will add four liquids to four more test tubes one third-filled with water (after making predictions of miscibility). Students will then explain what is happening and why at the molecular level in each of the cases. Students then add sodium chloride to the test tube already containing glycerol and water, predict, record, and explain results. Lastly, a small drop of dish soap could be added to the last test tube. Students would submit an informal lab report. For closure, as a large group, each lab group could share their reasoning as to why the substances behaved the way they did using the board to draw molecular diagrams of the substances Student Handout for Solutions Lab (Microsoft Word 32kB Aug2 09)

Teaching Notes and Tips

Assessment

Students will hand in an informal lab report that includes predictions, data table, and analysis. The analysis will include an explanation of how the substances combined or didn't combine for each case in molecular terms.

Standards

8.2.1.1.1 Matter

References and Resources