Chapter 12, Problem 12.79QP

Interpretation Introduction

Interpretation:

The molar heat of vaporization of Mercury has to be determined graphically from the vapor pressure measurements at different temperatures.

Concept Introduction:

• Molar heat of vaporization is defined as the quantity of heat required to vaporize one mole of substance at its boiling point.
• The heat of vaporization or molar heat of vaporization ${\text{ΔH}}_{\text{vap}}$ can be related to quantity of heat ‘q’ as follows –

$\text{q}\text{ =}{\text{ΔH}}_{\text{vap}}$

• Vapor pressure of a liquid can be related to molar heat of vaporization of the liquid by “Clausius – Clapeyron” equation as follows –

$\begin{array}{l}\text{ln}\text{P}\text{=}\frac{{\text{-ΔH}}_{\text{vap}}}{\text{R}}\left(\frac{\text{1}}{\text{T}}\right)\text{+}\text{C}\\ \text{Where}\text{T}\text{=}\text{Temperature}\\ \text{ P}\text{=}\text{vapor}\text{pressure}\text{of}\text{the}\text{liquid}\text{}\text{at}\text{temperature}\text{T}\\ {\text{ΔH}}_{\text{vap}}\text{=}\text{Molar}\text{heat}\text{of}\text{vaporization}\\ \text{R}\text{=}\text{Universal}\text{Gas constant}\text{.}\end{array}$