Identification and Analysis of Student Conceptions Used to Solve Chemical Equilibrium Problems

Abstract

This study identified and quantified chemistry conceptions students use when solving chemical equilibrium problems requiring application of Le Chatelier's principle, and explored the feasibility of designing a paper and pencil test to accomplish these purposes. A 10-item pencil and paper, two-tier diagnostic instrument, the Test to Identify Student Conceptualizations (TISC), was developed and administered to 95 second-semester university general chemistry students after they received regular course instruction concerning equilibrium in homogeneous aqueous, heterogeneous aqueous, and homogeneous gaseous systems. To validate TISC, nine students from a stratified random sample were selected for interviews incorporating comparable chemistry problems. The probability that TISC correctly identified an answer given by a student in the interview was p = .64, whereas the probability that TISC correctly identified a reason given by a student in the interview was p = .49. Eleven prevalent incorrect student conceptions about chemical equilibrium were identified by TISC. Students consistently selected correct answers more frequently (53% of the time) than they provided correct reasons (33% of the time). The level of association between student answers and their respective reasons on each TISC item was quantified using conditional probabilities calculated from logistic regression coefficients. The Kuder-Richardson 20 reliability for TISC was .79. © 2000 John Wiley & Sons, Inc. J Res Sci Teach 37: 160–176, 2000