This article describes a laboratory module designed to help students understand how different compounds behave when they are dissolved in water. Students measure the conductivities of various aqueous solutions using handheld conductivity testers with LED displays. By counting the number of LEDs illuminated, students can differentiate between electrolytes and nonelectrolytes and approximate the relative numbers of ions in solution. This enables students to discover how ionic compounds dissociate when dissolved in water. The laboratory module introduces the model–observe–reflect–explain (MORE) thinking frame, an instructional tool that encourages students to connect their macroscopic observations with their understanding of the behavior of particles at the molecular level. These activities are designed for college-level general chemistry courses, but have also been adapted to the high-school level.
Supplement
Student handouts for a college-level general chemistry course, required supplies, sample results, instructor notes, examples of student work, and suggestions for grading are available.
Our Secondary School editors work hard to distill all the JCE materials to produce a fraction of particular interest to high school teachers. We call it CLIC.
In recent years we have worked hard to better match our advertisers with our readers. When shopping for chemistry education materials, visit our advertisers' WWW sites first.
Take JCE along on your outreach missions. Copies of the Journal, guest access to JCE Online, our publications catalog, and more are available for your participants.