Chapter 8, Problem 8.43NP

Interpretation Introduction

Interpretation: The temperature at which the two phases are in equilibrium at 350 bar needs to be determined for conversion of gray solid tin to white solid tin in equilibrium with each other at 1 bar and 18°C.

Concept Introduction: All substances can mainly exist in three phases; solid, liquid and gas. These three phases can convert into each other by the application of temperature and pressure such as heating of solid leads to the conversion to liquid and then gaseous state of matter.

The enthalpy change during the fusion of solid to liquid is called as enthalpy of fusion that is denoted as ${\text{ΔH}}_{\text{fus}}$ . Similarly, the enthalpy of vaporization involves in the vaporization of liquid to gas is called as enthalpy of vaporization that is denoted as ${\text{ΔH}}_{\text{vap}}$ .

Clausius - Clapeyron equation proposed the relationship between the pressure and temperature for conditions of equilibrium between two phases; vapor and solid for sublimation or solid and liquid for fusion.

  $\text{ln}\frac{{\text{P}}_{\text{f}}}{{\text{P}}_{\text{i}}}\text{=}\frac{{\text{ΔH}}_{\text{vap}}}{\text{R}}\left(\frac{\text{1}}{{\text{T}}_{\text{f}}}\text{-}\frac{\text{1}}{{\text{T}}_{\text{i}}}\right)$

Here, P is pressure, T is temperature, R is Universal gas constant and ${\text{ΔH}}_{\text{vap}}$ is change in enthalpy of vaporization.