Aqueous Equilibria: Acids, Bases, and Solubility. A General Chemistry Laboratory Experiment

TCE

The Chemical Educator

ISSN: 1430-4171 (electronic version)

Table of Contents

Abstract Volume 5 Issue 6 (2000) pp 312-314

Aqueous Equilibria: Acids, Bases, and Solubility. A General Chemistry Laboratory Experiment

Michael A. Janusa,* Cynthia M. Lamberty, and Glenn Lo

Department of Physical Sciences, Nicholls State University, P.O. Box 2022, Thibodaux, LA 70310

Published online: 17 November 2000

Abstract. We refer to two major types of general chemistry freshman laboratory experiments: discovery and cookbook. The typical Freshman enrolled in general chemistry has the skills to perform an experiment that is somewhere between cookbook and discovery, and we have developed a laboratory experiment that is midway between these extremes. This experiment aids the student's understanding of the concept of aqueous equilibria. In this experiment, students are asked to prepare and measure the pH of a variety of acidic and basic solutions. Students are also asked to calculate pH values from literature dissociation constants and dissociation constants from their experimental pH values. This experiment demonstrates the relationships between dissociation constants, percent ionization, pH and strength of acids and bases, as well as molar solubility and the solubility product constant, K_sp. A Mathcad-based prelaboratory activity provides a review of the concepts and engages students in what-if explorations.

Key Words: Laboratories and Demonstrations; general chemistry; acid-base; pH

(*) Corresponding author. (E-mail: phsc-maj@mail.nich.edu)

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Supporting Materials:

MathCad examples (25 KB) 10.1007/s00897000433b

Student Handout (140 KB) 10.1007/s00897000433c (rev. 4/19/01)