Phase Changes

[Selena Yu 1H]

Are there any phase changes from vapor --> liquid, liquid --> solid, or vapor --> solid? Are these changes just the exothermic process of the ones we talked about in class?

[Sean Cheah 1E]

The names for the phase changes you listed are, in order, condensation, freezing, and deposition. These are indeed simply the reverse of vaporization, melting, and sublimation, respectively, and are therefore exothermic.

[smurphy1D]

For all phase change equations, do we always subtract the end phase by the beginning phase stat, just like we would do in equilibrium equations?

[Wilson 2E]

Yes, it's just the change in heat between the final and initial states. The deltaH between states will be the same, only the sign will be different (e.g. solid -> liquid deltaH = 50, liquid -> solid deltaH = -50)