Question

Entropy and Solid Phase Change It is quite common for a solid to change from one solid state structure to another at a temperature below its melting point. For example, sulfur undergoes a phase change from the a-orthorhombic form (Sg; density=2.07 g/cm3) to the B-monoclinic form (Sg; density=2.00 g/cm3) as it is warmed above 95.3 °C. Assuming that AH for this phase change is 0.310 kJ/mol, calculate AS for this phase change. Submit Answer Tries 0/5

Answer 1

Entropy change due to a phase transition is given by,

$\Delta S=\frac{\Delta H}{T}$

Now,

$\Delta H=0.310kJ/mol = 310 J/mol$

$T=95.3^oC=(95.3+273)K= 368.3K$

$So,\Delta S=\frac{310\, J/mol}{368K}=0.8424\, J.K^{-1}.mol^{-1}$