Physical Quantities and their Changes: Difficulties and Perceptions by Chemistry Students

Abstract Physical quantities pertain to the description of systems and their changes pertain to the description of processes. A variety of imprecisions and mistakes in the corresponding definitions and utilisation have been identified in the works of chemistry students. This paper presents an overview of the types of confusion that appear more frequently within general chemistry and physical chemistry courses. The physical quantities concerned range from state properties (like temperature and volume) to thermodynamic functions (enthalpy, entropy, etc.) to more specifically chemical concepts (like reaction rate). Hypotheses on the causes behind the confusions are proposed and discussed within a comprehensive framework including method-related aspects. The rate/extent to which the confusions appear, and the range of contexts concerned, suggest the opportunity of designing ad hoc remedial measures and prevention measures, the latter being relevant for the pre-tertiary levels of education.