Chapter 8, Problem 8.36NP

Interpretation Introduction

Interpretation:

The value of ${\text{ΔH}}_{\text{fusion}}^{\text{0}}$ and ${\text{ΔS}}_{\text{fusion}}^{\text{0}}$ needs to be calculated from the given densities of the solid and liquid phases of the substance

Concept Introduction:

The relationship between pressure (P), temperature (T) and the enthalpy change ( ΔH) associated with a phase transition reaction is given via the Clapeyron equation:

  $\left(\frac{\partial \text{P}}{\partial \text{T}}\right)\text{ = }\frac{\text{ΔH}}{\text{TΔV}}\text{ -----(1)}$

Here, ΔH and ΔV are the molar enthalpy and volume between the two phases

T is the temperature of phase transition

For a reaction at equilibrium, the free energy change ΔG = 0, therefore based on the thermodynamic equation

  $\begin{array}{l}\text{dG = VdP }-\text{ SdT}\\ \left(\frac{\partial \text{P}}{\partial \text{T}}\right)=\frac{\text{ΔS}}{\text{ΔV}}\text{ -----(2)}\end{array}$

For phase transition reactions the entropy change is given as:

  $\text{ΔS = }\frac{\text{ΔH}}{\text{T}}\text{ -------(3)}$