Answer:
Any phase change that takes you from higher energy particles to lower energy particles is exothermic.
Similarly, any phase change that takes you from lower energy particles to higher energy particles is endothermic.
The idea here is that in order to change the state of a substance you must either provide with energy or take away energy.
When you're going from particles that are in a lower energetic state to particles that are in a higher energetic state, you must provide energy.
This implies that the process will be endothermic since heat must be absorbed. You will thus have -- I'll ignore plasma here and stick to the traditional phase changes
solid to liquid →melting→requires an energy liquid to gas →evaporation→requires energy solid to gas →sublimation→requires an energy
When you're going from particles that are in a higher energy state to particles that are in a lower energy state, you must take away energy.
This implies that the process will be exothermic since heat is being released. You will thus have
gas to liquid →condensation→gives off a energy liquid to solid →freezing→gives off an energy gas to solid →deposition→gives off an energy
And there you have it -- six phase changes, three exothermic and three endothermic correspond to the three traditional phases of matter, liquid, solid, and gas.
When you're going from particles that are in a higher energy state to particles that are in a lower energy state, you must take away energy.
