The entropy versus temperature plot for phases α and β at 1 bar pressure is given. ST and S0 are entropies of the phases at temperatures T and 0 K, respectively.
(see diagram)
The transition temperature for α to β phase change is 600 K and CP,β−CP,α=1Jmol−1K−1. Assume (CP,β−CP,α) is independent of temperature in the range of 200 to 700K.CP,α and CP,β are heat capacities of α and β phases, respectively.
The value of enthalpy change, Hβ−Hα (in Jmol−1 ), at 300 K is ____.
Answer: 300
Solution
At the transition temperature (600 K), the two phases are in equilibrium: