Concentration is a fundamental concept in chemistry and critically important in a laboratory setting. However, while students can demonstrate competence in algorithmic problem solving of concentration problems, prior evidence suggests that students may not have a clear conceptualization of the meaning or implications of those calculations. To address this gap, a concentration assessment composed of 17 multiple-choice items was developed. Items on the instrument were designed to reflect the three levels of chemistry knowledge – symbolic, macroscopic, and particulate – and tap student understanding of the relationships between concentration, volume, and mass of solute, while avoiding cueing of rote calculations. The instrument was administered to primarily first-year general chemistry students on either side of a laboratory activity that was intended to help students develop a conceptual understanding of concentration. In this presentation, we will report on student response patterns across different models (symbolic, macroscopic, and particulate), on particular misconceptions and interpretations, and on how much change might be engendered by focused instruction.

Assessing student understanding of concentration at the symbolic, macroscopic, and particulate levels

ACS Spring 2022

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