Identifying Liquid–Gas System Misconceptions and Addressing Them Using a Laboratory Exercise on Pressure–Temperature Diagrams of a Mixed Gas Involving Liquid–Vapor Equilibrium

This study focuses on students’ understandings of a liquid–gas system with liquid–vapor equilibrium in a closed system using a pressure–temperature (P–T) diagram. By administrating three assessment questions concerning the P–T diagrams of liquid–gas systems to students at the beginning of undergraduate general chemistry course, lack of understanding of the fundamental concepts concerning liquid–vapor equilibria, the ideal gas law, and boiling points was identified. A learning program for liquid–gas systems was then designed for students at the undergraduate general chemistry level to address this issue. It consists of a laboratory experiment and postlaboratory exercise and is intended to provide integrated student understanding. During the learning program, students actively used the related concepts to explain the physical chemistry of a liquid–gas system and integrated the concepts to explain practical systems in their daily lives using a P–T diagram. An outline of the learning program is reported on the basis of our educational practice.