Chapter 16, Problem 105QRT

(a)

Interpretation Introduction

Interpretation:

Whether the statement “the enthalpy change for the reaction is zero” is true or false has to be stated.

Concept Introduction:

The standard enthalpy of formation that is ${\Delta }_{\text{f}}H°$ is the enthalpy of formation for a reaction which involves formation of one mole of product from pure reactants in their standard states at a particular temperature.  The standard enthalpies of formations are used for estimating the enthalpy of a reaction.

(b)

Interpretation Introduction

Interpretation:

Whether the statement “the entropy change for the reaction is zero” is true or false has to be stated.

Concept Introduction:

The term entropy is used to represent the randomness in a system.  When a system moves from an ordered arrangement to a less ordered arrangement, then the entropy of the system increases.  The second law of thermodynamics state that “the entropy of the system either increases or remains the same.”

(c)

Interpretation Introduction

Interpretation:

Whether the statement “the Gibbs free energy change for the reaction is zero” is true or false has to be stated.

Concept Introduction:

The Gibbs free energy of a system is directly related to the equilibrium constant of a reaction.  The Gibbs free energy of a system is defined as the enthalpy of the system minus the product of the temperature times the entropy of the system.  The Gibbs free energy of the system is a state function as it is defined in terms of thermodynamic properties that are state functions.  The symbol for equilibrium constant is $K_{\text{P}}$.

(d)

Interpretation Introduction

Interpretation:

Whether the statement “the ${\Delta }_{\text{r}}H°$ and ${\Delta }_{\text{r}}S°$ have the same sign” is true or false has to be stated.

Concept Introduction:

The Gibbs free energy of a system is defined as the enthalpy of the system minus the product of the temperature times the entropy of the system.  The Gibbs free energy of the system is a state function as it is defined in terms of thermodynamic properties that are state functions.

(e)

Interpretation Introduction

Interpretation:

Whether the statement “the ${\Delta }_{\text{r}}H°/T={\Delta }_{\text{r}}S°$ at temperature $T$” is true or false has to be stated.

Concept Introduction:

The randomness present in the system is known as its entropy.  It is an extensive property.  At equilibrium, the entropy of the system is zero.  It is denoted by $S$.  The entropy that is measured under the standard conditions of temperature is known as standard entropy.  The standard entropy change is denoted by $\Delta S°$.