Making the implicit explicit in the teaching of chemical equilibrium

CHED 386

David J. Yaron1, Jodi Davenport2, Michael Karabinos1, James G. Greeno3, and Gaea Leinhardt3. (1) Department of Chemistry, Carnegie Mellon University, 4400 Fifth Ave., Pittsburgh, PA 15213, (2) Department of Psychology, Carnegie Mellon University, 5000 Forbes Ave., Pittsburgh, PA 15213, (3) Learning Research and Development Center (LRDC), University of Pittsburgh, 3939 O'Hara Street, Pittsburgh, PA 15260
A detailed task analysis, combined with student interviews, reveals a set of concepts and strategies that are important in chemical equilibrium problem solving but that are left implicit in traditional instruction. For instance, the distinction between the current state of a chemical system versus the equilibrium state is important to problem conceptualization, but is not emphasized sufficiently in current instruction. The task analysis also reveals a single strategy that encompasses a broad range of chemical equilibrium problem solving. This strategy involves a two step process: determination of majority species followed by determination of minority species. In addition to providing a single uniform approach to solving a broad range of problems (including acid-base and solubility chemistry), emphasis is shifted away from a strictly quantitative approach to a qualitative analysis of the chemical system. New instructional materials based on these findings will be presented along with initial data on student learning.