Forward and Reverse phase change

[Andrew Nguyen 2K]

Will the enthalpy of vaporization be the opposite of the enthalpy of condensation, or would there be another value? Is this the same for all of the phase changes?

[Sunny Xiao 1A]

Yes, they would be equivalent but of opposite signs. This holds true for all that are related, but just inverse phase changes (liquid--> solid vs solid --> liquid).

[Devon Shao 1E]

Yes, the enthalpy of vaporization would be the same numerical value as the enthalpy of condensation, but with an opposite sign. This is because if you write out the phase change reaction formula for condensation the same way Dr. Lavelle did so for vaporization in the lecture, you would find that it is: vapor --> liquid. Then, if you follow the same next step that Dr. Lavelle did in the lecture, you would find that

deltaHcondensation = Hliquid - Hvapor

Which is the opposite of the given equation for enthalpy of vaporization.

Sorry for the weird formatting, I hope this helped explain it a bit more quantitatively?

[Mikayla 2G]

They will be equivalent because moving from one phase to another and back is just like a forward and reverse reaction

for example: solid + Energy <---> liquid
as a solid is heated up and melts, the energy put in is stored in the liquid. When the liquid freezes/ solidifies, it will release the heat/energy that is stored, following the law of thermodynamics that energy is neither created nor destroyed.

[Elena Chan 2L]

Yes! You're correct. The enthalpy of vaporization is just the opposite process of the enthalpy of condensation with opposite signs. It can be represented by ΔHvaporization = −ΔHcondensation. If you look at the phase changes and their equations, they all work hand in hand with each other. Hope this helps!

[Tsii 2H]

Yea, the enthalpy of vaporization is equivalent to the enthalpy of condensation just with opposite signs.

[Amy Wong 2F]

Yes, the enthalpy of vaporization and enthalpy of condensation are equivalent with opposite signs. It's the amount of energy required to either break the bonds when a liquid becomes a gas, or the energy released when a gas becomes a liquid, therefore they have opposite signs.

[oliviahelou]

Yes, they are equivalent with the only difference that you must change the signs.