Chapter 6, Problem 6.30P

(a)

Interpretation Introduction

Interpretation:

Whether the value of $q_{\text{sys}}$ in the phase change represented in the circle is positive $(+)$, negative $(-)$, or zero is to be determined.

Concept introduction:

Heat $\left(q\right)$ is the energy transferred as a consequence of the difference of the temperature between the system and surrounding.

The heat released by the system is negative and heat taken by the system is positive.

(b)

Interpretation Introduction

Interpretation:

Whether the value of $\Delta E_{\text{system}}$ in the phase change represented in the circle is positive $(+)$, negative $(-)$, or zero is to be determined.

Concept introduction:

The internal energy of a process is the summation of the kinetic energy and potential energy associated with the process. In the case of a reaction, the change in internal energy $\left(\Delta E\right)$ is the difference in the energy of the product and reactant.

Heat $\left(q\right)$ is the energy transferred as a consequence of the difference of the temperature between the system and surrounding.

Work $\left(w\right)$ is the energy needed to move an object in the opposite direction of the force applied.

The expression to calculate $\left(\Delta E\right)$ is as follows:

$\Delta E=q+w$        (1)

Here,

$\Delta E$ is the internal energy of the system.

$q$ is the heat released or absorbed.

$w$ is the work done by the system or on the system.

(c)

Interpretation Introduction

Interpretation:

Whether the value of $\Delta E_{\text{universe}}$ in the phase change represented in the circle is positive $(+)$, negative $(-)$, or zero is to be determined.

Concept introduction:

According to the law of conservation of energy “the total energy of the system plus surrounding remains constant”. The expression of the law of conservation of energy is as follows:

$\Delta E_{\text{universe}}=\Delta E_{\text{system}}+\Delta E_{\text{surrounding}}$        (2)

Or,

$\Delta E_{\text{universe}}=0$

Here,

$\Delta E_{\text{system}}$ is the internal energy of the system.

$\Delta E_{\text{universe}}$ is the internal energy of the universe.

$\Delta E_{\text{surrounding}}$ is the internal energy of the surrounding.