Chapter 18, Problem 68GQ

Interpretation Introduction

Interpretation:

The vapour pressure of ethanol at $\text{37 }°\text{C}$ should be estimated using thermodynamic data which then has to be expressed in millimeters of mercury.

Concept introduction:

The vapor pressure of a substance is related to its enthalpy of vaporisation by the

expression,

$\ln \left(\frac{p_2}{p_1}\right)=\frac{\Delta H_{\text{vap}}}{\text{R}}\left(\frac{1}{T_1}-\frac{1}{T_2}\right)$

Here, $p_1$ and $p_2$ are the vapour pressures at two different temperatures $T_1$ and $T_2$.

This equation is known as Clausius-Clapeyron equation and is used to estimate the vapour pressure of a substance at a particular temperature.