Chemistry - Thermodynamics - II Question with Solution | TestHub

(P) Vaporization ($l\to g$) increases randomness ($\Delta S_{sys}>0$), but since H₂O(l) is stable at $100^{\circ }C$ and $2atm$, vaporization is non-spontaneous ($\Delta S_{total}<0$). $\to$ (4)

(Q) Condensation ($g\to l$) decreases randomness ($\Delta S_{sys}<0$), but since H₂O(g) is stable at $100^{\circ }C$ and $0.5atm$, condensation is non-spontaneous ($\Delta S_{total}<0$). $\to$ (5)

(R) Freezing ($l\to s$) decreases randomness ($\Delta S_{sys}<0$), and because water spontaneously freezes below $0^{\circ }C$ at $1atm$, the process is spontaneous ($\Delta S_{total}>0$). $\to$ (1)

(S) Melting ($s\to l$) increases randomness ($\Delta S_{sys}>0$), and because increasing pressure favors the denser liquid phase of water, melting is spontaneous at $2atm$ ($\Delta S_{total}>0$). $\to$ (2)