Question 1

Δ\DeltaΔ Ssys can be directly related to the heat, q. Which of statements A-D is not true regarding this relationship? If all are true, select E.

Accepted Answer

A)   ( Δ\DeltaΔ Ssys can always be determined from the heat transferred during the actual process.) 
B)   For a reversible spontaneous endothermic process, both q and  Δ\DeltaΔ Ssys will be positive.
C)   The more heat that is transferred, the larger the magnitude of the entropy change.
D)   The higher the temperature at which heat is transferred, the lower the entropy change.
E)   All of the above are true.

Question 2

The entropy of a NaCl crystal is ________

Accepted Answer

A)   an intensive property and a state function.
B)   an intensive property and a path function.
C)   an extensive property and a state function.
D)   an extensive property and a path function.
E)   not appropriately described in terms of an intensive property, an extensive property, a state function, or a path function.

Question 3

The change in standard molar entropy, $\Delta$S$\degree$ for the following reaction is 494.6 J/mol . K at 25$\degree$C.
2KClO3(s) $\leftrightarrow$2KCl(s) + 3O2(g)
What is the standard molar entropy of O2(g) at 25$\degree$C?
S°(KClO3, s)
= 143.1 J/mol . K
S°(KCl, s)
= 82.6 J/mol . K

Accepted Answer

Question 4

At body temperature, many proteins have a well-defined structure that is essential to their
Function. However, as the temperature is raised, the structure changes and the protein is no longer functional. This process is referred to as protein denaturation. What can be deduced from this information about the signs of the enthalpy and entropy changes for denaturation?

Accepted Answer

A)   ( Δ\DeltaΔ H > 0 and Δ\DeltaΔ S > 0) 
B)   ( Δ\DeltaΔ H > 0 and  Δ\DeltaΔ S 
C)   ( Δ\DeltaΔ H Δ\DeltaΔ S > 0) 
D)   ( Δ\DeltaΔ H Δ\DeltaΔ S 
E)   There is insufficient information to deduce anything about the signs of  Δ\DeltaΔ H and  Δ\DeltaΔ S.

Question 5

NO gas is converted to NO2 gas according to the following reaction:
NO(g)  +  12\frac { 1 } { 2 }21​  O2(g)   →ightarrow→  NO2(g) 
What is the standard entropy change when 0.5 mol of NO gas reacts with 0.5 mol of O2 gas?   Substance S∘(J/mol⋅K) NO(g) 210.7O2(g) 205.0NO2(g) 240.0\begin{array} { l c } 	ext { Substance } & \boldsymbol { S } ^ { \circ } ( \mathbf { J } / \mathbf { m o l } \cdot \mathbf { K } )  \\mathrm { NO } ( g )  & 210.7 \\mathrm { O } _ { 2 } ( g )  & 205.0 \\mathrm { NO } _ { 2 } ( g )  & 240.0\end{array} Substance NO(g) O2​(g) NO2​(g) ​S∘(J/mol⋅K) 210.7205.0240.0​

Accepted Answer

A)   -36.6 J/K
B)   -175.7 J/K
C)   -83.4 J/K
D)   +83.4 J/K
E)   +36.6 J/K

Question 6

Which statement about the reaction below, where en = ethylenediamine (H2NCH2CH2NH2) , is not correct?
Cr(NH3) 63+ + 3en ↔\leftrightarrow↔ Cr(en) 33+ + 6NH3

Accepted Answer

A)   The reaction is product-favored because the entropy of the system increases.
B)   The Lewis basicity of the amino groups in en is comparable to that of the ammonia molecules.
C)   The reaction is reactant-favored because the concentration of ammonia on the right side is higher than the concentration of en on the left side.
D)   The reaction enthalpy is small because the Cr-NH3 and Cr-en bond strengths are very similar.
E)   Both Cr(NH3) 63+ and Cr(en) 33+ have an octahedral coordination geometry and a coordination number of 6.

Question 7

What is the overall standard free-energy change for the following two reactions?
A + B  →\rightarrow→  C 
 Δ\DeltaΔ G  °  rxn =  Δ\DeltaΔ G1
C + D  →\rightarrow→  E 
 Δ\DeltaΔ G ° rxn=  Δ\DeltaΔ G2

Accepted Answer

A)   ( Δ\DeltaΔ G1 +  Δ\DeltaΔ G2) 
B)   ( Δ\DeltaΔ G1 -  Δ\DeltaΔ G2) 
C)   ( Δ\DeltaΔ G2 -  Δ\DeltaΔ G1) 
D)  ( Δ\DeltaΔ G1 Δ\DeltaΔ G2) 
E)  ( Δ\DeltaΔ G1/ Δ\DeltaΔ G2)

Question 8

According to the second law of thermodynamics, the change in the entropy of the universe ( Δ\DeltaΔ Suniv)  during a spontaneous reaction is ________

Accepted Answer

A)   zero.
B)   negative.
C)   positive.
D)   less than the change in entropy of the system ( Δ\DeltaΔ Ssys) .
E)   greater than the change in entropy of the system ( Δ\DeltaΔ Ssys) .

Question 9

Nitrogen monoxide molecules can react to form dinitrogen oxide and nitrogen dioxide. Determine the equilibrium constant for this reaction under standard conditions from the following data and note whether the reaction is product-favored or reactant-favored.
$\Delta$G°(NO, g) = 86.6 kJ/mol
$\Delta$G°(N2O, g) = 104.2 kJ/mol
$\Delta$G°(NO2, g) = 51.3 kJ/mol

Accepted Answer

K = 1.9 *1...

Question 10

Determine  Δ\DeltaΔ S  ∘rxn\begin{array} { l } \circ\\mathrm { rxn }\end{array}∘rxn​  for H2(g)  + I2(g)  ↔\leftrightarrow↔   2HI(g)  given the following information:   Substance S∘(J/mol⋅K) H2(g) 130.58I2(g) 116.73HI(g) 206.3\begin{array} { l c } 	ext { Substance } & \mathbf { S } ^ { \circ } ( \mathbf { J } / \mathbf { m o l } \cdot \mathbf { K } )  \\mathrm { H } _ { 2 } ( g )  & 130.58 \\mathrm { I } _ { 2 } ( g )  & 116.73 \\mathrm { HI } ( g )  & 206.3\end{array} Substance H2​(g) I2​(g) HI(g) ​S∘(J/mol⋅K) 130.58116.73206.3​

Accepted Answer

A)   -41.10 J/K
B)   -165.29 J/K
C)   +398.75 J/K
D)   +165.29 J/K
E)   +41.10 J/K

Question 11

Which of the following statements is/are correct? A large equilibrium constant means that ________
I. the standard free-energy change for the reaction is large and negative.
II. the standard free-energy change for the reaction is large and positive.
III. the reaction greatly favors formation of the products.
IV. only a small amount of product is produced at equilibrium.

Accepted Answer

A)   I only
B)   II only
C)   both I and III
D)   both II and IV
E)   both II and III

Question 12

What are the signs of$\Delta$H°, $\Delta$S°, and $\Delta$G° for the conversion of liquid water to ice at 10°C and 1 atm? Briefly explain each answer.

Accepted Answer

<img  loading="lazy" src="/assets/images/blured-textbook.svg" class="d-inline m-1" alt="blured image" width="139" height="30">H° is negative, because heat m...

Question 13

An oxygen molecule can have several different modes of motions. One type of motion is ________

Accepted Answer

A)   kinetic energy.
B)   potential energy.
C)   vibrational.
D)   elastic.
E)   Boltzmann.

Question 14

Indicate which of the following has the smallest standard molar entropy (S°) .

Accepted Answer

A)   CH4(g) 
B)   CH3CH2OH(l) 
C)   H2O(s) 
D)   Na(s) 
E)   He(g)

Question 15

In a spontaneous process, which of the following always increases?

Accepted Answer

A)   the entropy of the system
B)   the entropy of the surroundings
C)   the entropy of the universe
D)   the entropy of the system and the universe
E)   the entropy of the system, the surroundings, and the universe

Question 16

Which of the following processes will lead to a decrease in the entropy of the system?

Accepted Answer

A)   Salt crystals dissolve in water.
B)   Air escapes from a hole in a balloon.
C)   Iron and oxygen react to form rust.
D)   Ice melts in your hand.
E)   None of these leads to a negative change in the entropy of the system, because they are all spontaneous.

Question 17

The entropy of fusion for ice at 0°C and 1 atm is 22 J/mol .K. How many joules of heat are required to melt a typical ice cube at 0°C and 1 atm? Assume an ice cube is about 1 oz or 28
g.

Accepted Answer

The answer of The entropy of fusion for ice at...

Question 18

Alcohols for use as biofuels can be produced from glucose that is obtained from starch and cellulose in plants. Use the information in the table below to determine the free-energy change and whether or not this reaction is spontaneous at 78°C, which is the boiling point of an ethanol-water azeotrope.
C6H12O6(s)   ⟶\longrightarrow⟶  2CH3CH2OH(l)  + 2CO2(g)    Compound S∘ΔHf∘[J/(mol⋅K) ] Glucose (s) (kJ/mol) 212 Ethanol (l) −1,274161 Carbon dioxide (g) −278214\begin{array} { | c | c | c | } \hline 	ext { Compound } & & \boldsymbol { S } ^ { \circ } \& \Delta \boldsymbol { H } _ { \mathbf { f } } ^ { \circ } & { [ \mathbf { J } / ( \mathbf { m o l } \cdot \mathbf { K } )  ] } \\hline 	ext { Glucose } ( s )  & ( \mathbf { k J } / \mathbf { m o l } )  & 212 \\hline 	ext { Ethanol } ( l )  & - 1,274 & 161 \\hline 	ext { Carbon dioxide } ( g )  & - 278 & 214 \\hline\end{array} Compound  Glucose (s)  Ethanol (l)  Carbon dioxide (g) ​ΔHf∘​(kJ/mol) −1,274−278​S∘[J/(mol⋅K) ]212161214​​

Accepted Answer

A)   -6 kJ, spontaneous
B)   +76 kJ, not spontaneous
C)   -76 kJ, spontaneous
D)   -258 kJ, not spontaneous
E)   -258 kJ, spontaneous

Question 19

The enthalpy of fusion for benzene (C6H6)  is 127.40 kJ/kg, and its melting point is 5.5°C. What is the entropy change when 1 mole of benzene melts at 5.5°C?

Accepted Answer

A)   9.95 kJ/K
B)   35.7 J/K
C)   1,809 J/K
D)   1.81 J/K
E)   127.40 kJ/K

Question 20

Determine the value of  Δ\DeltaΔ G° for the reaction
2NO2(g)   ↔\leftrightarrow↔ N2O4(g) 
Given  SubstanceS∘(J/(mol⋅K) ) ΔHf∘(kJ/mol) NO2(g) 33.2240.0 N2O4(g) 9.2304.2 \begin{array}{lcr} Substance&&S^{\circ}(\mathrm{J} /(\mathbf{m o l} \cdot \mathbf{K}) ) \& \Delta \boldsymbol{H}_{\mathbf{f}}^{\circ} & \ & (\mathbf{k J} / \mathbf{m o l})  & \ \mathrm{NO}_{2}(g)  & 33.2 & 240.0 \ \mathrm{~N}_{2} \mathrm{O}_{4}(g)  & 9.2 & 304.2\end{array} SubstanceNO2​(g)  N2​O4​(g) ​ΔHf∘​(kJ/mol) 33.29.2​S∘(J/(mol⋅K) ) 240.0304.2​

Accepted Answer

A)   -4.8 kJ
B)   +4.8 kJ
C)   +52.3 kJ
D)   -52.3 kJ
E)   -43 kJ

Exam 18: Thermodynamics: Spontaneous and Nonspontaneous Reactions and Processes

What are the signs of $\Delta$ H°, $\Delta$ S°, and $\Delta$ G° for the conversion of liquid water to ice at 10°C and 1 atm? Briefly explain each answer.

Correct Answer
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H° is negative, because heat m...
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The entropy of a NaCl crystal is ________

Correct Answer
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Indicate which of the following has the smallest standard molar entropy (S°) .

Correct Answer
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The change in standard molar entropy, $\Delta$ S $\degree$ for the following reaction is 494.6 J/mol . K at 25 $\degree$ C. 2KClO₃(s) $\leftrightarrow$ 2KCl(s) + 3O₂(g) What is the standard molar entropy of O₂(g) at 25 $\degree$ C? S°(KClO₃, s) = 143.1 J/mol . K S°(KCl, s) = 82.6 J/mol . K

Correct Answer
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Correct Answer
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K = 1.9 *1...
View Answer

In a spontaneous process, which of the following always increases?

Correct Answer
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According to the second law of thermodynamics, the change in the entropy of the universe ( $\Delta$ S_univ) during a spontaneous reaction is ________

Correct Answer
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Which statement about the reaction below, where en = ethylenediamine (H₂NCH₂CH₂NH₂) , is not correct? Cr(NH₃) ₆³⁺ + 3en $\leftrightarrow$ Cr(en) ₃³⁺ + 6NH₃

Correct Answer
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What is the overall standard free-energy change for the following two reactions? A + B $\rightarrow$ C $\Delta$ G ^° _rxn= $\Delta$ G₁ C + D $\rightarrow$ E $\Delta$ G ^° _rxn= $\Delta$ G₂

Correct Answer
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$\Delta$ S_sys can be directly related to the heat, q. Which of statements A-D is not true regarding this relationship? If all are true, select E.

Correct Answer
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Correct Answer
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The entropy of fusion for ice at 0°C and 1 atm is 22 J/mol .K. How many joules of heat are required to melt a typical ice cube at 0°C and 1 atm? Assume an ice cube is about 1 oz or 28 g.

Correct Answer
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An oxygen molecule can have several different modes of motions. One type of motion is ________

Correct Answer
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Which of the following processes will lead to a decrease in the entropy of the system?

Correct Answer
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The enthalpy of fusion for benzene (C₆H₆) is 127.40 kJ/kg, and its melting point is 5.5°C. What is the entropy change when 1 mole of benzene melts at 5.5°C?

Correct Answer
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Exam 18: Thermodynamics: Spontaneous and Nonspontaneous Reactions and Processes

What are the signs of Δ\DeltaΔ H°, Δ\DeltaΔ S°, and Δ\DeltaΔ G° for the conversion of liquid water to ice at 10°C and 1 atm? Briefly explain each answer.

Correct AnswerverifiedH° is negative, because heat m...View AnswerShow Answer

The entropy of a NaCl crystal is ________

Correct AnswerverifiedShow Answer

Indicate which of the following has the smallest standard molar entropy (S°) .

Correct AnswerverifiedShow Answer

Correct AnswerverifiedShow Answer

Correct AnswerverifiedShow Answer

Correct AnswerverifiedShow Answer

Correct AnswerverifiedK = 1.9 *1...View AnswerShow Answer

In a spontaneous process, which of the following always increases?

Correct AnswerverifiedShow Answer

Correct AnswerverifiedShow Answer

Correct AnswerverifiedShow Answer

According to the second law of thermodynamics, the change in the entropy of the universe ( Δ\DeltaΔ Suniv) during a spontaneous reaction is ________

Correct AnswerverifiedShow Answer

Which statement about the reaction below, where en = ethylenediamine (H2NCH2CH2NH2) , is not correct? Cr(NH3) 63+ + 3en ↔\leftrightarrow↔ Cr(en) 33+ + 6NH3

Correct AnswerverifiedShow Answer

What is the overall standard free-energy change for the following two reactions? A + B →\rightarrow→ C Δ\DeltaΔ G ° rxn = Δ\DeltaΔ G1 C + D →\rightarrow→ E Δ\DeltaΔ G ° rxn= Δ\DeltaΔ G2

Correct AnswerverifiedShow Answer

Δ\DeltaΔ Ssys can be directly related to the heat, q. Which of statements A-D is not true regarding this relationship? If all are true, select E.

Correct AnswerverifiedShow Answer

Correct AnswerverifiedShow Answer

Correct AnswerverifiedShow Answer

The entropy of fusion for ice at 0°C and 1 atm is 22 J/mol .K. How many joules of heat are required to melt a typical ice cube at 0°C and 1 atm? Assume an ice cube is about 1 oz or 28 g.

Correct AnswerverifiedShow Answer

An oxygen molecule can have several different modes of motions. One type of motion is ________

Correct AnswerverifiedShow Answer

Which of the following processes will lead to a decrease in the entropy of the system?

Correct AnswerverifiedShow Answer

The enthalpy of fusion for benzene (C6H6) is 127.40 kJ/kg, and its melting point is 5.5°C. What is the entropy change when 1 mole of benzene melts at 5.5°C?

Correct AnswerverifiedShow Answer

What are the signs of $\Delta$ H°, $\Delta$ S°, and $\Delta$ G° for the conversion of liquid water to ice at 10°C and 1 atm? Briefly explain each answer.

Correct Answer
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H° is negative, because heat m...
View Answer

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K = 1.9 *1...
View Answer

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According to the second law of thermodynamics, the change in the entropy of the universe ( $\Delta$ S_univ) during a spontaneous reaction is ________

Correct Answer
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Which statement about the reaction below, where en = ethylenediamine (H₂NCH₂CH₂NH₂) , is not correct? Cr(NH₃) ₆³⁺ + 3en $\leftrightarrow$ Cr(en) ₃³⁺ + 6NH₃

Correct Answer
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What is the overall standard free-energy change for the following two reactions? A + B $\rightarrow$ C $\Delta$ G ^° _rxn= $\Delta$ G₁ C + D $\rightarrow$ E $\Delta$ G ^° _rxn= $\Delta$ G₂

Correct Answer
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$\Delta$ S_sys can be directly related to the heat, q. Which of statements A-D is not true regarding this relationship? If all are true, select E.

Correct Answer
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The enthalpy of fusion for benzene (C₆H₆) is 127.40 kJ/kg, and its melting point is 5.5°C. What is the entropy change when 1 mole of benzene melts at 5.5°C?

Correct Answer
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