ENERGY BALANCES – Tools for Structured Problem Solving and Visual Learners

The material and energy balances course is a crucial course in the chemical engineering curriculum. In the energy balances part of the course, definition of the reference state and calculation of specific enthalpies relative to the reference state are confusing concepts for students. Our aim in this talk is to provide some tools to clarify the role played by the reference state and the importance of applying a reference state consistently. The first tool uses maps to develop the reference state concept, targeting visual learners. The second step is to use enthalpy-temperature diagrams to illustrate the path independence of changes in enthalpy, and the impact of choosing different reference states. The specific enthalpy data is organized in material balance tables for calculations, reinforcing the importance of structured problem solving practices. Finally, at several points in the unit, summary checklists and decision trees are used to reinforce the concepts.