Chapter 11, Problem 11.34SP

Interpretation Introduction

Interpretation:

The heat of vaporization $\left(\Delta H_{\text{vap}}\right)$ calculated from the plot and data is to be compared.

Concept introduction:

Clausius-Clapeyron equation is used to estimate the vapor pressure at another temperature if vapor pressure at one temperature and enthalpy of vaporization is known.

The expression of Clausius-Clapeyron equation is as follows:

$\ln P_{\text{vap}}=\left(\frac{-\Delta H_{\text{vap}}}{\text{R}}\right)\left(\frac{1}{T}\right)+C$

Where,

• $P_{\text{vap}}$ is the vapor pressure.
• $\Delta H_{\text{vap}}$ is the heat of vaporization.
• $T$ is the temperature.
• $C$ is the constant.
• $\text{R}$ is the universal gas constant.

For the two pressures and temperature, the Clausius-Clapeyron equation is modified as follows:

$\ln \frac{P{}_1}{P_2}=\left(\frac{\Delta H_{\text{vap}}}{\text{R}}\right)\left(\frac{1}{T_2}-\frac{1}{T_1}\right)$

The conversion factor to convert $°\text{C}$ to Kelvin is,

$T\left(\text{K}\right)=T\left(°\text{C}\right)+273$

The conversion factor to convert $\text{kJ}$ to $\text{J}$ is as follows:

$1\text{ kJ}=\text{1000 J}$