Conductivity of Strong Electrolytes, Weak Electrolytes, and Non-Electrolytes Presentation

A lecture presentation (draft) to accompany the Conductivity of Strong Electrolytes, Weak Electrolyte, and Non-Electrolytes Demonstration and Class Activity.

Includes visual images, main student activities, computer animations, computer simulations, videos, and a sample of clicker questions.  This presentation is available to download from the menu.

This presentation illustrates the conductivity properties of a strong electrolyte, a weak electrolyte, and a non-electrolyte. Deionized water fails to light the light bulb in the conductivity tester.  A light bulb conductivity tester does not light up at all when the electrodes are inserted into either solid granular sodium chloride or solid granular sucrose. However, when solid NaCl dissolves in water, the sodium chloride solution lights the bulb brightly.  When solid sucrose dissolves in water the sucrose solution fails to light the bulb. A 1M acetic acid solution makes the bulb glow dimly. 

A computer simulation representing the conductivity of solutions experiment with a light bulb can accompany this demonstration or it can be used as a before, during or after class activity.

A computer animation of the migration of Na+ ions and Cl- ions during a conductivity test accompanies this demonstration.

Curriculum Notes 

This demonstration can be used to illustrate how the number of ion particles in solution classify an aqueous solution as a strong electrolyte , weak electrolyte or non-electrolyte. This demonstration can be used to help discuss topics such as the solution process, intermolecular forces, or the relative strengths of chemical bonds vs. IMF. The effectiveness of this demonstration is increased when 1) students make their own predictions, observations, and inferences; 2) draw particle level diagrams of all of the tested solutions and solids; and 3) answer questions and write explanations about solutions. 

There is a draft of a POGIL-like student activity that can accompany (and enhance) this demonstration.

Learning Objectives

1.  Explain why water is a polar molecule and how five or six water molecules interact with substances to participate in the dissolving process.  

2. From physics, apply the concepts of "unlike charges attract", dipole moment, and vectors to help explain why polar substances and soluble ionic substances dissolve in water.  

3.Categorize an aqueous solution as being a strong electrolyte, weak electrolyte, or non-electrolyte.

4.  Represent solid ionic substances, polar covalent substances, and covalent substances using particle level diagrams.

5.  Represent the dissolving process of solid ionic substances and  polar covalent substances, and covalent substances using particle level diagrams and chemical equations

6. Clearly illustrate and explain the distinctions among strong electrolyte, weak electrolyte, and non-electrolyte solutions.

7.  Identify weak acids, strong acids, weak bases, and strong bases.

© Copyright 2012 Email: Randy Sullivan, University of Oregon Chemistry Department and UO Libraries Interactive Media Group