4.6 Phosphine exists in three allotropic forms, known as the , and forms. The ...

4.6 Phosphine exists in three allotropic forms, known as the α, β and

γ forms. The α and β forms are in equilibrium at 49.43 K, the α and

γ forms at 30.29 K. Obtain the molar heat of transformation for the γ

form changing to the α form at 30.29 K from the following data:

(i) The entropy of the α form at 49.43 K is 34.03 J mol–1 K–1.

(ii) The entropy change in heating the γ form from 0K to 30.29K is 11.22 J mol–1 K–1.

(iii) The entropy change in heating the α form from 30.29 K to 49.43 K is 20.10 J mol–1 K–1.