Chapter 15, Problem 15.112SP

Interpretation Introduction

Interpretation:

The vapour pressure of water at $\text{60°C}$ has to be determined.

Concept Introduction:

Clausius-Clapeyron equation:

  $\text{ln}\text{P}\text{=}-\left(\frac{{\text{Δ}}_{\text{vap}}{\text{H}}_{\text{0}}}{\text{RT}}\right)\text{+}\text{C}$

From this relationship we can calculate the molar enthalpy of vaporization by knowing the corresponding temperature and pressure values.

If we have pressures at two different temperatures, then enthalpy of vaporization can be calculated by,

  $\text{ln}\frac{{\text{P}}_{\text{2}}}{{\text{p}}_{\text{1}}}\text{=}\text{-}\frac{{\text{Δ}}_{\text{vap}}{\text{H}}_{\text{0}}}{\text{R}}\left[\frac{\text{1}}{{\text{T}}_{\text{2}}}\text{-}\frac{\text{1}}{{\text{T}}_{\text{1}}}\right]$

The van’t Hoff equation which relates the equilibrium constant of a reaction to change in temperature is given below:

    $\text{ln}\frac{{\text{K}}_{\text{1}}}{{\text{K}}_{\text{2}}}\text{=}\frac{{\text{Δ}}_{\text{vap}}{\text{H}}_{\text{0}}}{\text{R}}\left[\frac{\text{1}}{{\text{T}}_{\text{2}}}-\frac{\text{1}}{{\text{T}}_{\text{1}}}\right]$