Duduli

The changes of phase which take place at constant temperature & pressure & in which heat is either absorbed or evolved during change of phase are called first order phase transitions. → In first order please transitions, the entropy & density (or volume) change.

Second order phase transitions can be defined as the phenomenon that takes place with no change in entropy & volume at constant temperature & pressure. e.g  ★ Transition of a ferromagnetic material to a paramagnetic material at the curie point. ★ Order-disorder transitions in chemical compounds & alloys.