   Chapter 18, Problem 102SCQ

Chapter
Section
Textbook Problem

Consider the reaction of NO and Cl2 to produce NOCI. (a) What is ΔS°(system) for this reaction? (b) Does ΔS°(system) change with temperature? (c) Does ΔS°(surroundings) change with temperature? (d) Does ΔS°(universe) always change with an increase in temperature? (e) Do exothermic reactions always lead to positive values of ΔS°(universe)? (f) Is the NO + Cl2 reaction spontaneous at 298 K? At 700 K?

(a)

Interpretation Introduction

Interpretation:

The  ΔSo(system) for reaction between NO(g) and Cl2(g) should be determined.

Concept introduction:

The universe consists of two parts, systems and surroundings. The entropy change for the universe is the sum of entropy change for the system and for surroundings.

ΔSo(universe)= ΔSo(system)+ΔSo(surroundings)

The ΔSo(universe) should be greater than zero for a spontaneous process.

The  ΔSo(system) can be calculated by the following expression,

ΔSo(system)=ΔrS°nS°(products)-nS°(reactants)

The ΔSo(surroundings) can be calculated by the following expression,

ΔSo(surroundings)=rHoT

Here, ΔrH° is the enthalpy change for the reaction.

The Gibbs free energy or the free energy change is a thermodynamic quantity represented by ΔGo. It is related to entropy and entropy by the following expression,

ΔGo= ΔHo- TΔSo

ΔGo is also related to the equilibrium constant K by the equation,

ΔrGo= -RTlnKp

The rearranged expression is,

Kp= eΔrGoRT

Explanation

The  ΔSo(system) for the reaction is calculated below.

Given:

Refer to Appendix L for the values of standard entropies.

The standard entropy of NOCl(g) is 261.8 J/Kmol.

The standard entropy of NO(g) is 210.76 J/Kmol.

The standard entropy of Cl2(g) is 223.08 J/Kmol.

The balanced chemical equation is:

NO(g)+12Cl2(g)NOCl(g)

The  ΔSo(system) can be calculated by the following expression,

ΔSo(system)=ΔrS°nS°(products)-nS°(reactants)=[(1 mol NOCl(g)/mol-rxn)S°

(b)

Interpretation Introduction

Interpretation:

It should be identified that  ΔSo(system) changes with temperature or not.

Concept introduction:

The universe consists of two parts, systems and surroundings. The entropy change for the universe is the sum of entropy change for the system and for surroundings.

ΔSo(universe)= ΔSo(system)+ΔSo(surroundings)

The ΔSo(universe) should be greater than zero for a spontaneous process.

The  ΔSo(system) can be calculated by the following expression,

ΔSo(system)=ΔrS°nS°(products)-nS°(reactants)

The ΔSo(surroundings) can be calculated by the following expression,

ΔSo(surroundings)=rHoT

Here, ΔrH° is the enthalpy change for the reaction.

The Gibbs free energy or the free energy change is a thermodynamic quantity represented by ΔGo. It is related to entropy and entropy by the following expression,

ΔGo= ΔHo- TΔSo

ΔGo is also related to the equilibrium constant K by the equation,

ΔrGo= -RTlnKp

The rearranged expression is,

Kp= eΔrGoRT

(c)

Interpretation Introduction

Interpretation:

It should be identified that ΔSo(surroundings) changes with temperature.

Concept introduction:

The universe consists of two parts, systems and surroundings. The entropy change for the universe is the sum of entropy change for the system and for surroundings.

ΔSo(universe)= ΔSo(system)+ΔSo(surroundings)

The ΔSo(universe) should be greater than zero for a spontaneous process.

The  ΔSo(system) can be calculated by the following expression,

ΔSo(system)=ΔrS°nS°(products)-nS°(reactants)

The ΔSo(surroundings) can be calculated by the following expression,

ΔSo(surroundings)=rHoT

Here, ΔrH° is the enthalpy change for the reaction.

The Gibbs free energy or the free energy change is a thermodynamic quantity represented by ΔGo. It is related to entropy and entropy by the following expression,

ΔGo= ΔHo- TΔSo

ΔGo is also related to the equilibrium constant K by the equation,

ΔrGo= -RTlnKp

The rearranged expression is,

Kp= eΔrGoRT

(d)

Interpretation Introduction

Interpretation:

It should be identified that ΔSo(surroundings) changes with increase in temperature or not.

Concept introduction:

The universe consists of two parts, systems and surroundings. The entropy change for the universe is the sum of entropy change for the system and for surroundings.

ΔSo(universe)= ΔSo(system)+ΔSo(surroundings)

The ΔSo(universe) should be greater than zero for a spontaneous process.

The  ΔSo(system) can be calculated by the following expression,

ΔSo(system)=ΔrS°nS°(products)-nS°(reactants)

The ΔSo(surroundings) can be calculated by the following expression,

ΔSo(surroundings)=rHoT

Here, ΔrH° is the enthalpy change for the reaction.

The Gibbs free energy or the free energy change is a thermodynamic quantity represented by ΔGo. It is related to entropy and entropy by the following expression,

ΔGo= ΔHo- TΔSo

ΔGo is also related to the equilibrium constant K by the equation,

ΔrGo= -RTlnKp

The rearranged expression is,

Kp= eΔrGoRT

(e)

Interpretation Introduction

Interpretation:

It should be identified that does exothermic reaction will always results in positive ΔSo(universe) value.

Concept introduction:

The universe consists of two parts, systems and surroundings. The entropy change for the universe is the sum of entropy change for the system and for surroundings.

ΔSo(universe)= ΔSo(system)+ΔSo(surroundings)

The ΔSo(universe) should be greater than zero for a spontaneous process.

The  ΔSo(system) can be calculated by the following expression,

ΔSo(system)=ΔrS°nS°(products)-nS°(reactants)

The ΔSo(surroundings) can be calculated by the following expression,

ΔSo(surroundings)=rHoT

Here, ΔrH° is the enthalpy change for the reaction.

The Gibbs free energy or the free energy change is a thermodynamic quantity represented by ΔGo. It is related to entropy and entropy by the following expression,

ΔGo= ΔHo- TΔSo

ΔGo is also related to the equilibrium constant K by the equation,

ΔrGo= -RTlnKp

The rearranged expression is,

Kp= eΔrGoRT

(f)

Interpretation Introduction

Interpretation:

It should be identified that reaction of NO(g) and Cl2(g) is spontaneous or not.

Concept introduction:

The universe consists of two parts, systems and surroundings. The entropy change for the universe is the sum of entropy change for the system and for surroundings.

ΔSo(universe)= ΔSo(system)+ΔSo(surroundings)

The ΔSo(universe) should be greater than zero for a spontaneous process.

The  ΔSo(system) can be calculated by the following expression,

ΔSo(system)=ΔrS°nS°(products)-nS°(reactants)

The ΔSo(surroundings) can be calculated by the following expression,

ΔSo(surroundings)=rHoT

Here, ΔrH° is the enthalpy change for the reaction.

The Gibbs free energy or the free energy change is a thermodynamic quantity represented by ΔGo. It is related to entropy and entropy by the following expression,

ΔGo= ΔHo- TΔSo

ΔGo is also related to the equilibrium constant K by the equation,

ΔrGo= -RTlnKp

The rearranged expression is,

Kp= eΔrGoRT

Still sussing out bartleby?

Check out a sample textbook solution.

See a sample solution

The Solution to Your Study Problems

Bartleby provides explanations to thousands of textbook problems written by our experts, many with advanced degrees!

Get Started

What are the features of a healthy high-fat diet?

Understanding Nutrition (MindTap Course List)

Do lipases degrade (a) cholesterol or (b) fatty acids?

Introduction to General, Organic and Biochemistry

Does the cell cycle refer to mitosis as well as meiosis?

Human Heredity: Principles and Issues (MindTap Course List)

In which domain and kingdom are humans classified?

Biology: The Dynamic Science (MindTap Course List)

Why is the Moon red during a total lunar eclipse?

Horizons: Exploring the Universe (MindTap Course List)

Consider the two vectors A=3i2j and B=i4j. Calculate(a) A + B, (b) A B, (c) |A + B|, (d) |A B|, and (e) the d...

Physics for Scientists and Engineers, Technology Update (No access codes included) 