Question 1

State the second and third laws of thermodynamics.

Accepted Answer

All spontaneous processes are

Question 2

Use the given data at 298 K to calculate $\Delta$G$\degree$for the reaction

Accepted Answer

A)  129.3 kJ 
B)  133.6 kJ 
C)  196.0 kJ 
D)  199.8 kJ 
E)  229.6 kJ 
A)  129.3 kJ 
B)  133.6 kJ 
C)  196.0 kJ 
D)  199.8 kJ 
E)  229.6 kJ

Question 3

Which of the following values is based on the Third Law of Thermodynamics?

Accepted Answer

A)  ($\Delta$H $\degree$f = 0 for Al(s) at 298 K) 
B) ($\Delta$G $\degree$f = 0 for H2(g) at 298 K) 
C)  (S $\degree$= 51.446 J/(mol·K) for Na(s) at 298 K) 
D)  (q sys 2O(l)$\rightarrow$H2O(s) at 0 $\degree$
C)  
E)  None of these choices is correct. 
A)  ($\Delta$H $\degree$f = 0 for Al(s) at 298 K) 
B) ($\Delta$G $\degree$f = 0 for H2(g) at 298 K) 
C)  (S $\degree$= 51.446 J/(mol·K) for Na(s) at 298 K) 
D)  (q sys 2O(l)$\rightarrow$H2O(s) at 0 $\degree$
C)  
E)  None of these choices is correct.

Question 4

"A diamond is forever" is one of the most successful advertising slogans of all time. But is it true? For the reaction shown below, calculate the standard free energy change at 298 K and determine whether or not a diamond is "forever." C(diamond) $\degree$C(graphite)
Data: $\Delta$Hf$\degree$(diamond) = 1.895 kJ/mol; S$\degree$(diamond) = 2.337 J mol¯1 K¯1; S$\degree$(graphite) = 5.740 J mol¯1K¯1.

Accepted Answer

A)  ($\Delta$G$\degree$ = 2.19 kJ; forever 
B)  ($\Delta$G$\degree$= -1.90 kJ; not forever) 
C)  ($\Delta$G$\degree$ = -2.90 kJ; not forever) 
D) ( $\Delta$G$\degree$ = 1.90 kJ; forever) 
E)  ($\Delta$G$\degree$ = < -1000 kJ; not forever) 
A)  ($\Delta$G$\degree$ = 2.19 kJ; forever 
B)  ($\Delta$G$\degree$= -1.90 kJ; not forever) 
C)  ($\Delta$G$\degree$ = -2.90 kJ; not forever) 
D) ( $\Delta$G$\degree$ = 1.90 kJ; forever) 
E)  ($\Delta$G$\degree$ = < -1000 kJ; not forever)

Question 5

Which of the following is true for a system at equilibrium?

Accepted Answer

A)  ($\Delta$S$\degree$sys = $\Delta$S$\degree$surr) 
B)  ($\Delta$S$\degree$sys = -$\Delta$S$\degree$surr) 
C)  ($\Delta$S$\degree$sys = $\Delta$S$\degree$surr = 0 
D)  ($\Delta$S$\degree$univ > 0) 
E)  None of these choices is a sufficient condition. 
A)  ($\Delta$S$\degree$sys = $\Delta$S$\degree$surr) 
B)  ($\Delta$S$\degree$sys = -$\Delta$S$\degree$surr) 
C)  ($\Delta$S$\degree$sys = $\Delta$S$\degree$surr = 0 
D)  ($\Delta$S$\degree$univ > 0) 
E)  None of these choices is a sufficient condition.

Question 6

For a chemical reaction to be spontaneous at all temperatures, which of the following conditions must be met?

Accepted Answer

A)  ($\Delta$S$\degree$  > 0, $\Delta$H$\degree$ > 0) 
B)  ($\Delta$S$\degree$  > 0, $\Delta$H$\degree$  0) 
E)  It is not possible for a reaction to be spontaneous at all temperatures. 
A)  ($\Delta$S$\degree$  > 0, $\Delta$H$\degree$ > 0) 
B)  ($\Delta$S$\degree$  > 0, $\Delta$H$\degree$  0) 
E)  It is not possible for a reaction to be spontaneous at all temperatures.

Question 7

In which one of the following pairs will the first system have a higher entropy than the second? Assume P and T are the same for each pair, unless stated otherwise.

Accepted Answer

A)  1 mole He(g); 1 mole Kr(g) 
B)  1 mole O2(g); 2 mole O(g) 
C)  1 mole CH4(g); 1 mole C2H6(g) 
D)  1 mole Xe(g) at 1 atmosphere; 1 mole Xe(g) at 0.5 atmosphere 
E)  20 one-dollar bills distributed randomly among 20 people; 20 one-dollar bills distributed randomly among 10 people 
A)  1 mole He(g); 1 mole Kr(g) 
B)  1 mole O2(g); 2 mole O(g) 
C)  1 mole CH4(g); 1 mole C2H6(g) 
D)  1 mole Xe(g) at 1 atmosphere; 1 mole Xe(g) at 0.5 atmosphere 
E)  20 one-dollar bills distributed randomly among 20 people; 20 one-dollar bills distributed randomly among 10 people

Question 8

Which relationship or statement best describes $\Delta$S$\degree$ for the following reaction? HgS(s) + O2(g) $\rightarrow$ Hg(l) + SO2(g)

Accepted Answer

A) ( $\Delta$S$\degree$$\approx$ 0) 
B)  ($\Delta$S$\degree$  0) 
D)  ($\Delta$S$\degree$= $\Delta$H$\degree$/T) 
E)  More information is needed to make a reasonable prediction. 
A) ( $\Delta$S$\degree$$\approx$ 0) 
B)  ($\Delta$S$\degree$  0) 
D)  ($\Delta$S$\degree$= $\Delta$H$\degree$/T) 
E)  More information is needed to make a reasonable prediction.

Question 9

Which relationship or statement best describes $\Delta$S $\degree$ for the following reaction? 2NH3(g) + 2ClF3(g) $\rightarrow$ 6HF(g) + N2(g) + Cl2(g)

Accepted Answer

A)  ($\Delta$SF $\degree$$\approx$ 0) 
B)  ($\Delta$S $\degree$  0) 
D)  ($\Delta$S $\degree$ = $\Delta$H $\degree$/T) 
E)  More information is needed to make a reasonable prediction. 
A)  ($\Delta$SF $\degree$$\approx$ 0) 
B)  ($\Delta$S $\degree$  0) 
D)  ($\Delta$S $\degree$ = $\Delta$H $\degree$/T) 
E)  More information is needed to make a reasonable prediction.

Question 10

A chemical reaction has $\Delta$H$\degree$  = 42.8 kJ and $\Delta$S$\degree$  = 92.5 J/K, at 25$\degree$ C. Calculate the temperature at which $\Delta$G$\degree$ = 0. State any approximation involved in your calculation.

Accepted Answer

T = 463 K. The calculation is

Question 11

In the expression, S = k ln W, W is called the number of microstates. Explain clearly the meaning of the word "microstate," and why a system under a given set of conditions normally has many microstates.

Accepted Answer

A microstate is a specific, quantized st

Question 12

You are given pure samples of pentane, $ \mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{CH}_{2} \mathrm{CH}_{2} \mathrm{CH}_{3}(l) $, and 1,3-pentadiene, $ \mathrm{CH}_{2}=\mathrm{CHCH}=\mathrm{CHCH}_{3}(l) $ What prediction would you make concerning their standard molar entropies at 298 K?

Accepted Answer

A)  S$\degree$pentane > S$\degree$1,3-pentadiene 
B)  S $\degree$pentane 1,3-pentadiene 
C)  S$\degree$pentane $\approx$S$\degree$1,3-pentadiene 
D)  S$\degree$pentane &#61501; S$\degree$1,3-pentadiene + 2*  
E)  More information is needed to make reasonable predictions. 
A)  S$\degree$pentane > S$\degree$1,3-pentadiene 
B)  S $\degree$pentane 1,3-pentadiene 
C)  S$\degree$pentane $\approx$S$\degree$1,3-pentadiene 
D)  S$\degree$pentane &#61501; S$\degree$1,3-pentadiene + 2*  
E)  More information is needed to make reasonable predictions.

Question 13

(p. Various sections) For a given reaction, a change in the pressure may result in a change in the sign of $\Delta$G.

Accepted Answer

A) True 
 B)False

Question 14

Consider the figure below which shows $\Delta$G$\degree$ for a chemical process plotted against absolute temperature.   From this plot, it is reasonable to conclude that:

Accepted Answer

A) ( $\Delta$H$\degree$ > 0, $\Delta$S$\degree$ > 0) B) ($\Delta$H$\degree$ > 0, $\Delta$S$\degree$ 0) D) ($\Delta$H$\degree$ < 0, $\Delta$S$\degree$ < 0) E) None of these choices is correct. A) ( $\Delta$H$\degree$ > 0, $\Delta$S$\degree$ > 0) B) ($\Delta$H$\degree$ > 0, $\Delta$S$\degree$ 0) D) ($\Delta$H$\degree$ < 0, $\Delta$S$\degree$ < 0) E) None of these choices is correct.

Question 15

A certain process has $\Delta$0H $\degree$> 0, $\Delta$S $\degree$  0. The values of $\Delta$H $\degree$ and $\Delta$S $\degree$do not depend on the temperature. Which of the following is a correct conclusion about this process?

Accepted Answer

A)  It is non-spontaneous at all T. 
B)  It is spontaneous at high T. 
C)  It is spontaneous at low T. 
D)  It is spontaneous at all T. 
E)  None of these conclusions is correct. 
A)  It is non-spontaneous at all T. 
B)  It is spontaneous at high T. 
C)  It is spontaneous at low T. 
D)  It is spontaneous at all T. 
E)  None of these conclusions is correct.

Question 16

Which relationship or statement best describes $\Delta$S$\degree$ for the following reaction?

Accepted Answer

A)  ($\Delta$S$\degree$ $\approx$ 0) 
B)  ($\Delta$S$\degree$ 0) 
D)  ($\Delta$S$\degree$ = $\Delta$H$\degree$/T) 
E)  More information is needed to make a reasonable prediction. 
A)  ($\Delta$S$\degree$ $\approx$ 0) 
B)  ($\Delta$S$\degree$ 0) 
D)  ($\Delta$S$\degree$ = $\Delta$H$\degree$/T) 
E)  More information is needed to make a reasonable prediction.

Question 17

Which of the following conditions will ensure that a chemical reaction will definitely proceed in the forward direction, toward products?

Accepted Answer

A)  ($\Delta$H > 0) 
B)  ($\Delta$H sys > 0) 
D)  ($\Delta$Ssurr > $\Delta$Ssys) 
E)  ($\Delta$S > $\Delta$H/T) 
A)  ($\Delta$H > 0) 
B)  ($\Delta$H sys > 0) 
D)  ($\Delta$Ssurr > $\Delta$Ssys) 
E)  ($\Delta$S > $\Delta$H/T)

Question 18

Elemental boron can be formed by reaction of boron trichloride with hydrogen.   Calculate $\Delta$G$\degree$ for the reaction.

Accepted Answer

A)  -293.4 kJ 
B)  293.4 kJ 
C)  -102.8 kJ 
D)  102.8 kJ 
E)  None of these choices is correct. 
A)  -293.4 kJ 
B)  293.4 kJ 
C)  -102.8 kJ 
D)  102.8 kJ 
E)  None of these choices is correct.

Question 19

Which one of the following phase changes decreases the entropy of the system?

Accepted Answer

A)  melting 
B)  heating a gas 
C)  vaporization 
D)  condensation 
E)  sublimation 
A)  melting 
B)  heating a gas 
C)  vaporization 
D)  condensation 
E)  sublimation

Question 20

Elemental boron can be formed by reaction of boron trichloride with hydrogen.     If $\Delta$S$\degree$  = 80.3 J/K for the reaction above, what is S $\degree$ for BCl3(g)?

Accepted Answer

A)  -18.2 J/K*mol 
B)  18.2 J/K*mol 
C)  290.1 J/K*mol 
D)  355.4 J/K*mol 
E)  450.6 J/K*mol 
A)  -18.2 J/K*mol 
B)  18.2 J/K*mol 
C)  290.1 J/K*mol 
D)  355.4 J/K*mol 
E)  450.6 J/K*mol

State the second and third laws of thermodynamics.

Use the given data at 298 K to calculate $\Delta$ G $\degree$ for the reaction $Use the given data at 298 K to calculate \Delta G \degree for the reaction$ $Use the given data at 298 K to calculate \Delta G \degree for the reaction$

Which of the following values is based on the Third Law of Thermodynamics?

Which of the following is true for a system at equilibrium?

For a chemical reaction to be spontaneous at all temperatures, which of the following conditions must be met?

In which one of the following pairs will the first system have a higher entropy than the second? Assume P and T are the same for each pair, unless stated otherwise.

Which relationship or statement best describes $\Delta$ S $\degree$ for the following reaction? HgS(s) + O₂(g) $\rightarrow$ Hg(l) + SO₂(g)

Which relationship or statement best describes $\Delta$ S $\degree$ for the following reaction? 2NH₃(g) + 2ClF₃(g) $\rightarrow$ 6HF(g) + N₂(g) + Cl₂(g)

A chemical reaction has $\Delta$ H $\degree$ = 42.8 kJ and $\Delta$ S $\degree$ = 92.5 J/K, at 25 $\degree$ C. Calculate the temperature at which $\Delta$ G $\degree$ = 0. State any approximation involved in your calculation.

In the expression, S = k ln W, W is called the number of microstates. Explain clearly the meaning of the word "microstate," and why a system under a given set of conditions normally has many microstates.

You are given pure samples of pentane, $\mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{CH}_{2} \mathrm{CH}_{2} \mathrm{CH}_{3}(l)$ , and 1,3-pentadiene, $\mathrm{CH}_{2}=\mathrm{CHCH}=\mathrm{CHCH}_{3}(l)$ What prediction would you make concerning their standard molar entropies at 298 K?

(p. Various sections) For a given reaction, a change in the pressure may result in a change in the sign of $\Delta$ G.

A certain process has $\Delta$ 0H $\degree$ > 0, $\Delta$ S $\degree$ < 0, and $\Delta$ G $\degree$ > 0. The values of $\Delta$ H $\degree$ and $\Delta$ S $\degree$ do not depend on the temperature. Which of the following is a correct conclusion about this process?

Which relationship or statement best describes $\Delta$ S $\degree$ for the following reaction? $Which relationship or statement best describes \Delta S \degree for the following reaction?$

Which of the following conditions will ensure that a chemical reaction will definitely proceed in the forward direction, toward products?

Which one of the following phase changes decreases the entropy of the system?

Keys to the Study of Chemistry

The Components of Matter

Stoichiometry of Formulas and Equations

Three Major Classes of Chemical Reactions

Gases and the Kinetic-Molecular Theory

Thermochemistry: Energy Flow and Chemical Change

Quantum Theory and Atomic Structure

Electron Configuration and Chemical Periodicity

Models of Chemical Bonding

The Shapes of Molecules

Theories of Covalent Bonding

Intermolecular Forces: Liquids, Solids, and Phase Changes

The Properties of Mixtures: Solutions and Colloids

Periodic Patterns in the Main-Group Elements

Organic Compounds and the Atomic Properties of Carbon

Kinetics: Rates and Mechanisms of Chemical Reactions

Equilibrium: the Extent of Chemical Reactions

Acid-Base Equilibria

Ionic Equilibria in Aqueous Systems

Electrochemistry: Chemical Change and Electrical Work

The Elements in Nature and Industry

The Transition Elements and Their Coordination Compounds

Nuclear Reactions and Their Applications

Filters

Exam 20: Thermodynamics: Entropy, Free Energy, and the Direction of Chemical Reactions

State the second and third laws of thermodynamics.

Use the given data at 298 K to calculate Δ\DeltaΔ G °\degree° for the reaction

Which of the following values is based on the Third Law of Thermodynamics?

Which of the following is true for a system at equilibrium?

For a chemical reaction to be spontaneous at all temperatures, which of the following conditions must be met?

In which one of the following pairs will the first system have a higher entropy than the second? Assume P and T are the same for each pair, unless stated otherwise.

Which relationship or statement best describes Δ\DeltaΔ S °\degree° for the following reaction? HgS(s) + O2(g) →\rightarrow→ Hg(l) + SO2(g)

Which relationship or statement best describes Δ\DeltaΔ S °\degree° for the following reaction? 2NH3(g) + 2ClF3(g) →\rightarrow→ 6HF(g) + N2(g) + Cl2(g)

A chemical reaction has Δ\DeltaΔ H °\degree° = 42.8 kJ and Δ\DeltaΔ S °\degree° = 92.5 J/K, at 25 °\degree° C. Calculate the temperature at which Δ\DeltaΔ G °\degree° = 0. State any approximation involved in your calculation.

In the expression, S = k ln W, W is called the number of microstates. Explain clearly the meaning of the word "microstate," and why a system under a given set of conditions normally has many microstates.

(p. Various sections) For a given reaction, a change in the pressure may result in a change in the sign of Δ\DeltaΔ G.

Consider the figure below which shows Δ\DeltaΔ G °\degree° for a chemical process plotted against absolute temperature. From this plot, it is reasonable to conclude that:

A certain process has Δ\DeltaΔ 0H °\degree° > 0, Δ\DeltaΔ S °\degree° < 0, and Δ\DeltaΔ G °\degree° > 0. The values of Δ\DeltaΔ H °\degree° and Δ\DeltaΔ S °\degree° do not depend on the temperature. Which of the following is a correct conclusion about this process?

Which relationship or statement best describes Δ\DeltaΔ S °\degree° for the following reaction?

Which of the following conditions will ensure that a chemical reaction will definitely proceed in the forward direction, toward products?

Elemental boron can be formed by reaction of boron trichloride with hydrogen. Calculate Δ\DeltaΔ G °\degree° for the reaction.

Which one of the following phase changes decreases the entropy of the system?

Elemental boron can be formed by reaction of boron trichloride with hydrogen. If Δ\DeltaΔ S °\degree° = 80.3 J/K for the reaction above, what is S °\degree° for BCl3(g)?

Keys to the Study of Chemistry

The Components of Matter

Stoichiometry of Formulas and Equations

Three Major Classes of Chemical Reactions

Gases and the Kinetic-Molecular Theory

Thermochemistry: Energy Flow and Chemical Change

Quantum Theory and Atomic Structure

Electron Configuration and Chemical Periodicity

Models of Chemical Bonding

The Shapes of Molecules

Theories of Covalent Bonding

Intermolecular Forces: Liquids, Solids, and Phase Changes

The Properties of Mixtures: Solutions and Colloids

Periodic Patterns in the Main-Group Elements

Organic Compounds and the Atomic Properties of Carbon

Kinetics: Rates and Mechanisms of Chemical Reactions

Equilibrium: the Extent of Chemical Reactions

Acid-Base Equilibria

Ionic Equilibria in Aqueous Systems

Electrochemistry: Chemical Change and Electrical Work

The Elements in Nature and Industry

The Transition Elements and Their Coordination Compounds

Nuclear Reactions and Their Applications

Filters

Use the given data at 298 K to calculate $\Delta$ G $\degree$ for the reaction $Use the given data at 298 K to calculate \Delta G \degree for the reaction$ $Use the given data at 298 K to calculate \Delta G \degree for the reaction$

Which relationship or statement best describes $\Delta$ S $\degree$ for the following reaction? HgS(s) + O₂(g) $\rightarrow$ Hg(l) + SO₂(g)

Which relationship or statement best describes $\Delta$ S $\degree$ for the following reaction? 2NH₃(g) + 2ClF₃(g) $\rightarrow$ 6HF(g) + N₂(g) + Cl₂(g)

A chemical reaction has $\Delta$ H $\degree$ = 42.8 kJ and $\Delta$ S $\degree$ = 92.5 J/K, at 25 $\degree$ C. Calculate the temperature at which $\Delta$ G $\degree$ = 0. State any approximation involved in your calculation.

(p. Various sections) For a given reaction, a change in the pressure may result in a change in the sign of $\Delta$ G.

A certain process has $\Delta$ 0H $\degree$ > 0, $\Delta$ S $\degree$ < 0, and $\Delta$ G $\degree$ > 0. The values of $\Delta$ H $\degree$ and $\Delta$ S $\degree$ do not depend on the temperature. Which of the following is a correct conclusion about this process?

Which relationship or statement best describes $\Delta$ S $\degree$ for the following reaction? $Which relationship or statement best describes \Delta S \degree for the following reaction?$