 Consider the transition between two forms of solid tin, $\mathrm{Sn}(s$, gray $) \rightarrow \mathrm{Sn}(s$, white $)$. The two phases are in equilibrium at 1 bar and $18^{\circ} \mathrm{C}$. The densities for gray and white tin are 5750 and $7280 \mathrm{~kg} \mathrm{~m}^{-3}$, respectively, and the molar entropies for gray and white tin are 44.14 and $51.18 \mathrm{~J} \mathrm{~K}^{-1} \mathrm{~mol}^{-1}$, respectively. Calculate the temperature at which the two phases are in equilibrium at 350. bar.
-3.5