Chapter 7, Problem 7.15P

Interpretation Introduction

(a)

Interpretation:

The reference state that is used to generate the listed specific internal energies is to be stated.

Concept introduction:

The reference states are considered as the stable and pure states of the chemical substances. The change in specific internal energy and change in specific enthalpy is represented by $\Delta \stackrel{\wedge }{U}$ and $\Delta \stackrel{\wedge }{H}$ respectively. The relationship between $\Delta \stackrel{\wedge }{U}$ and $\Delta \stackrel{\wedge }{H}$ is shown below,

$\Delta \stackrel{\wedge }{H}=\Delta \stackrel{\wedge }{U}+\text{P}\Delta \stackrel{\wedge }{V}$

Interpretation Introduction

(b)

Interpretation:

The values of $\Delta \stackrel{\wedge }{U}\left(\text{kJ}/\text{mol}\right)$ and $\Delta \stackrel{\wedge }{H}\left(\text{kJ}/\text{mol}\right)$ for a process in which bromine vapor condensed at $300\text{K}$ and constant pressure are to be calculated. The value of $\Delta H\left(\text{kJ}\right)$ for $5.00\text{mol}$ of bromine undergoing the process is to be calculated.

Concept introduction:

The change in specific internal energy and change in specific enthalpy is represented by $\Delta \stackrel{\wedge }{U}$ and $\Delta \stackrel{\wedge }{H}$ respectively. The relationship between $\Delta \stackrel{\wedge }{U}$ and $\Delta \stackrel{\wedge }{H}$ is shown below,

$\Delta \stackrel{\wedge }{H}=\Delta \stackrel{\wedge }{U}+\text{P}\Delta \stackrel{\wedge }{V}$

Interpretation Introduction

(c)

Interpretation:

The heat that must be transferred to the gas to achieve the desired temperature increase by assuming that $\stackrel{\wedge }{U}$ is independent of pressure is to be calculated.

Concept introduction:

The change in specific internal energy and change in specific enthalpy is represented by $\Delta \stackrel{\wedge }{U}$ and $\Delta \stackrel{\wedge }{H}$ respectively. The relationship between $\Delta \stackrel{\wedge }{U}$ and $\Delta \stackrel{\wedge }{H}$ is shown below,

$\Delta \stackrel{\wedge }{H}=\Delta \stackrel{\wedge }{U}+\text{P}\Delta \stackrel{\wedge }{V}$

The equation for energy balance when there is only one output and one input stream is shown below.

$Q+W_s=\Delta U+\Delta E_{\text{k}}+\Delta E_{\text{p}}$

Interpretation Introduction

(d)

Interpretation:

The two reasons for the requirement of more heat than the amount calculated in part (c) is to be stated.

Concept introduction:

The reference states are considered as the stable and pure states of the chemical substances. The change in specific internal energy and change in specific enthalpy is represented by $\Delta \stackrel{\wedge }{U}$ and $\Delta \stackrel{\wedge }{H}$ respectively. The relationship between $\Delta \stackrel{\wedge }{U}$ and $\Delta \stackrel{\wedge }{H}$ is shown below,

$\Delta \stackrel{\wedge }{H}=\Delta \stackrel{\wedge }{U}+\text{P}\Delta \stackrel{\wedge }{V}$