Chapter 12, Problem 123FP

Interpretation Introduction

(a)

Interpretation:

An equation for the vapor pressure of C₂H₄(l) as a function of temperature should be derived if ${\Delta }_{vap}H=15.971+14.55T-0.160T^2$ in Jmol-1.

Concept introduction:

$\frac{dP}{dT}=\frac{{\Delta }_{vap}H}{T(V_g-V_l)}$

V_g − molar volume of the vapor

V_l− molar volume of the liquid

Compared to the molar volume of vapor, molar volume of liquid is negligible. Therefore $V_g\approx 0$. And if the vapor pressure is not unusually high, vapor is assumed to be an ideal gas.

Interpretation Introduction

(b)

Interpretation:

Normal boiling point of ethylene should be determined.

Concept introduction:

The normal boiling point of ethylene can be calculated using the following formula:

$\ln \left(\frac{P_1}{P_2}\right)=\frac{\left(15971\right)}{R}\left(\frac{1}{T_1}-\frac{1}{T_2}\right)+\frac{\left(14.55\right)}{R}\left(\frac{T_2}{T_1}\right)-\frac{\left(0.160\right)}{R}\left(T_2-T_1\right)$

Here, P is pressure, R is Universal gas constant and T is temperature.