An Analysis of Student Performance on Acid-Base Equilibria Problems Before and After Instruction
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Date
2020-05
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The Ohio State University
Abstract
Solving quantitative problems is an important feature of most undergraduate chemistry
courses. Students frequently struggle with these complex quantitative problems because they
require mathematical skills, conceptual understanding, and problem-solving strategies. The topic
of acid-base equilibria includes quantitative problems that are difficult for many students in
General Chemistry, and this same topic is also an important part of upper-level Analytical
Chemistry courses. General Chemistry students are novices when they first encounter this topic,
and students that complete Analytical Chemistry can be considered undergraduate experts. This
investigation aimed to understand how novice and expert students solve acid-base equilibria
problems and identify their problem-solving strategies, the heuristics they use, and any essential
skills that they demonstrate. Two open-response instruments were written to elicit student
problem-solving for questions involving strong electrolytes, weak electrolytes, neutralization
reactions, and titrations. The study design included testing before and after instruction for
General Chemistry students (n=169) and Analytical Chemistry students (n=34), and class
experiences characterized for both courses in terms of lecture, homework, and laboratory
activities. The open-response data were analyzed using a qualitative approach to characterize
conceptual understanding, problem-solving strategies, and errors. In general, successful
problem-solving strategies were the same for both novices and experts, including the application
of prior knowledge and essential skills to identify the problem concept and execute the correct
problem strategy. On the other hand, greater variability was found for the errors exhibited by
unsuccessful novice and expert students. The analysis suggests algorithmic heuristics are
commonplace, frequently without a deeper conceptual understanding.
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Keywords
chemical education, acid-base equilibria, problem-solving strategies