Chapter 8, Problem 8.33NP

Interpretation Introduction

Interpretation:

The change in the normal freezing point of water needs to be calculated at a pressure of 100 bar and 500 bar respectively

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 and T is the temperature of phase transition

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

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