Gas Phase Only vs Liquid Phase Only

[Jennifer_Lam_1A]

In lecture today, we went over page 39 in the course reader. Can someone please explain how do you know if it is a "gas phase only" reaction (T>333 K) or if it is a "liquid phase only" (T<333 K)

I understand how to find T and I understand why we have to look at this problem in three situations (T =, >, < 333 K) but I am unsure to what this actually means.

Thanks!

[Navarro_Bree_1D]

From the reaction: Br2(l) --> Br2(g), you know you are starting with a liquid and ending with a gas.

When T>333K, the temp is high enough to make the reaction spontaneous. Therefore the reaction is considered "gas phase only" because all of the liquid Br2 is becoming gaseous Br2.

When T<333K, the temp is NOT high enough. Therefore, liquid Br2 cannot become gaseous Br2. This is why the reaction is considered "liquid phase only."

Hope this clarifies things for you!