Phase Transitions: Thermodynamic Principles and Applications

This lecture covers the fundamental concepts of phase transitions in thermodynamics. It begins with a discussion on the stability conditions for entropy and thermodynamic potentials, emphasizing how violations lead to transitions from unstable to stable phases. The instructor illustrates these concepts using phase diagrams, highlighting the significance of solid, liquid, and gas phases, as well as critical points and triple points. The lecture also delves into latent heat, explaining the energy required for phase changes such as fusion and vaporization. The Clausius-Clapeyron relation is introduced, which describes how pressure and temperature affect phase transitions. The instructor provides practical examples, including the behavior of water and carbon dioxide under varying conditions. The session concludes with a discussion on Gibbs' phase rule, which relates the number of phases in equilibrium to the degrees of freedom in a system. Overall, the lecture integrates theoretical principles with experimental observations to enhance understanding of thermodynamic behavior during phase transitions.