版权所有：华东理工大学物理化学教研室 2 The simplest applications of thermodynamics to chemically significant systems are to the discussion of the phase transitions of pure substances. We shall see that a phase diagram is a map of the pressures and temperatures at which each phase of a substance is the most stable. 6. Physical transformation of pure substances版权所有：华东理工大学物理化学教研室 2 The simplest applications of thermodynamics to chemically significant systems are to the discussion of the phase transitions of pure substances. We shall see that a phase diagram is a map of the pressures and temperatures at which each phase of a substance is the most stable. 6. Physical transformation of pure substances