As O2(l) is cooled at 1 atm, it freezes at 54.5 K to form solid I. At

Question:

As O2(l) is cooled at 1 atm, it freezes at 54.5 K to form solid I. At a lower temperature, solid I rearranges to solid II, which has a different crystal structure. Thermal measurements show that ΔH for the I → II phase transition is –743.1 J/ mol, and DS for the same transition is 217.0 J K-1 mol-1. At what temperature are sol-ids I and II in equilibrium?