Abstract: Entropy is a fundamental function in physical chemistry, and the calculation of entropy change serves as a basic criterion for determining the direction of processes. This paper discusses various methods for deriving the entropy change calculation formula in teaching, which can enhance instructional quality and improve learning outcomes. Additionally, the paper introduces the calculation of entropy change for real gases in chemical engineering, thereby broadening students’ knowledge and illustrating the close connection between physical chemistry and practical issues in chemical engineering.

Key words: Physical chemistry, Entropy change, Ideal gas, Real gas