Question 1

The reaction of methane with water to form carbon dioxide and hydrogen is non-spontaneous at 298 K. At what temperature will this system make the transition from non-spontaneous to spontaneous? The data refer to 298 K.

Accepted Answer

A)   658 K
B)   683 K
C)   955 K
D)   1047 K
E)   1229 KF) A) and B)
G) A) and C)

Question 2

In tables of thermodynamic data provided in chemistry books, one finds $\Delta$H$\degree$ S1U1B1fS1U1B0, $\Delta$G$\degree$ S1U1B1fS1U1B0 and S$\degree$listed. Briefly, explain why the entropy data are supplied as S$\degree$, while the enthalpy and free energy data are in the form of $\Delta$H$\degree$ S1U1B1fS1U1B0 and $\Delta$G$\degree$ 1U1B1fS1U1B0, respectively.

Accepted Answer

The third law specifies the state of zer...

Question 3

You are given pure samples of ammonia, NH3(g) , and nitrogen trifluoride, NF3(g) . What prediction would you make concerning their standard molar entropies at 298 K?

Accepted Answer

A)   S °\degree° ammonia > S °\degree° nitrogen trifluoride
B)   S °\degree° ammonia °\degree° nitrogen trifluoride
C)   S °\degree° ammonia  ≈\approx≈  S °\degree° nitrogen trifluoride
D)   Other conditions need to be specified before a reliable prediction can be made.
E)   Even if more conditions are specified, a reliable prediction cannot be made. F) A) and E)
G) C) and E)

Question 4

A reaction has a positive value of $\Delta$H$\degree$  and a positive value of $\Delta$S$\degree$ . Draw a neat, labeled schematic plot to show how $\Delta$G$\degree$  (y-axis) will depend on absolute temperature (x-axis).

Accepted Answer

The answer of A reaction has a positive value of...

Question 5

The free energy of a perfect crystal at absolute zero, is zero.

Accepted Answer

A) True 
 B)False

Question 6

Which relationship or statement best describes  Δ\DeltaΔ S °\degree°  for the following reaction? 2H2S(g)  + 3O2(g)   →\rightarrow→ 2H2O(g)  + 2SO2(g)

Accepted Answer

A)   ( Δ\DeltaΔ S °\degree°≈\approx≈  0) 
B)   ( Δ\DeltaΔ S °\degree°  
C)   ( Δ\DeltaΔ S °\degree°  > 0) 
D)   ( Δ\DeltaΔ S °\degree° =  Δ\DeltaΔ H °\degree° /T) 
E)   More information is needed to make a reasonable prediction. F) D) and E)
G) A) and B) B

Question 7

A reaction has  Δ\DeltaΔ G= 10.0 kJ and  Δ\DeltaΔ G °\degree°  = 15.0 kJ at a temperature of 50 °\degree° C. Calculate the value of the reaction quotient Q under these conditions.

Accepted Answer

A)   0.16
B)   9.1 * 10¯5
C)   1.1 *104
D)   6.4
E)   6.0 * 10¯6 F) D) and E)
G) A) and B)

Question 8

Calculate  Δ\DeltaΔ G °\degree° for the combustion of propane.

Accepted Answer

A)   -2073.1 kJ
B)   -1387.3 kJ
C)   -598.5 kJ
D)   598.5 kJ
E)   2073.1 kJ F) A) and E)
G) B) and D)

Question 9

Which relationship or statement best describes  Δ\DeltaΔ S °\degree°  for the following reaction?
 Pb(s)  + Cl2(g)   →\rightarrow→  PbCl2(s)

Accepted Answer

A)   ( Δ\DeltaΔ S °\degree°   ≈\approx≈  0) 
B)  (  Δ\DeltaΔ S °\degree°  
C)   ( Δ\DeltaΔ S °\degree°  > 0) 
D)  (  Δ\DeltaΔ S °\degree°  =  Δ\DeltaΔ H °\degree° /T) 
E)   More information is needed to make a reasonable prediction. F) B) and E)
G) C) and E)

Question 10

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

Accepted Answer

A)  (  Δ\DeltaΔ S °\degree°   > 0,  Δ\DeltaΔ H °\degree°  > 0) 
B)   ( Δ\DeltaΔ S °\degree°   > 0,  Δ\DeltaΔ H °\degree° 
C)   ( Δ\DeltaΔ S °\degree°   Δ\DeltaΔ H °\degree°  
D)   ( Δ\DeltaΔ S °\degree°   Δ\DeltaΔ H °\degree°  > 0) 
E)   ( Δ\DeltaΔ G °\degree°  > 0)  F) C) and E)
G) None of the above

Question 11

Calculate Δ\DeltaΔ S  °\degree° for the reaction

Accepted Answer

A)   -254.96 J/K
B)   -198.02 J/K
C)   198.02 J/K
D)   254.96 J/K
E)   471.86 J/K F) B) and D)
G) A) and B)

Question 12

You are given pure samples of ethane, C2H6(g) , and toluene, C7H8(l) . What prediction would you make concerning their standard molar entropies at 298 K?

Accepted Answer

A)   S °\degree° ethane > S °\degree° toluene
B)   S °\degree° ethane °\degree° toluene
C)   S °\degree° ethane  ≈\approx≈  (S °\degree° toluene)  / 3
D)   S °\degree° ethane  ≈\approx≈ S °\degree° toluene
E)   Since toluene is much more complex than ethane, but ethane is in the gas phase while toluene is a liquid, none of these predictions can be confidently made without further information or calculations. F) B) and D)
G) All of the above

Question 13

Given: H2O(l)   →\rightarrow→  H2O(s) ,  Δ\DeltaΔ H °\degree°  = -6.02 kJ at 273K, calculate the entropy change of the surroundings ( Δ\DeltaΔ Ssurr)  when one mole of water freezes at 0 °\degree° C and a pressure of one atmosphere.

Accepted Answer

A)   22.1 J/K
B)   -22.1 J/K
C)   397 J/K
D)   -397 J/K
E)   0.022 J/K F) A) and B)
G) A) and C)

Question 14

Given: C2H2(g) $\rightarrow$ 2C(graphite) + H2(g), $\Delta$G$\degree$ = -209 kJ
A sample of gaseous C2H2 (acetylene, or ethyne) was stored for one year, yet at the end of this period, the sample remained unchanged and no graphite or hydrogen gas had been formed. Briefly explain why there is no inconsistency between the sign of $\Delta$G$\degree$ and the apparent stability of the sample.

Accepted Answer

Relative to graphite and hydrogen, acety...

Question 15

For any reaction, if $\Delta$G $\degree$ > 0, then K < 1.

Accepted Answer

A) True 
 B)False

Question 16

What is the free energy change,  Δ\DeltaΔ G °\degree°  , for the equilibrium between hydrogen iodide, hydrogen, and iodine at 453 °\degree° C?
 Kc = 0.020 c = 0.020   A)  6.4 kJ B)  8.8 kJ C)  15 kJ D)  19 kJ E)  24 kJ " class="answers-bank-image d-inline" rel="preload" >

Accepted Answer

A)   6.4 kJ
B)   8.8 kJ
C)   15 kJ
D)   19 kJ
E)   24 kJ F) A) and B)
G) All of the above

Question 17

In a spontaneous process, the entropy of the system always increases.

Accepted Answer

A) True 
 B)False  False

Question 18

Which of the following results in a decrease in the entropy of the system?

Accepted Answer

A)   O2(g) , 300 K  →\rightarrow→  O2(g) , 400 K
B)   H2O(s) , 0 °\degree° C  →\rightarrow→ H2O(l) , 0 °\degree° C
C)   N2(g) , 25 °\degree° C  →\rightarrow→  N2(aq) , 25 °\degree° C
D)   NH3(l) , -34.5 °\degree° C  →\rightarrow→ NH3(g) , -34.5 °\degree° C
E)   2H2O2(g)   →\rightarrow→  2H2O(g)  + O2(g)  F) B) and D)
G) D) and E)

Question 19

Which, if any, of the following processes is spontaneous under the specified conditions?

Accepted Answer

A)   H2O(l)   →\rightarrow→  H2O(s)  at 25 °\degree° C
B)   CO2(s)   →\rightarrow→  CO2(g)  at 0 °\degree° C
C)   2H2O(g)   →\rightarrow→ H2(g)  + O2(g) 
D)   C(graphite)   →\rightarrow→  C(diamond)  at 25 °\degree° C and 1 atm pressure
E)   None of these choices is spontaneous. F) All of the above
G) C) and E) B

Question 20

A reaction is proceeding towards equilibrium. At a certain stage, the concentrations of reactants and products are such that  Δ\DeltaΔ G  =  Δ\DeltaΔ G °\degree°  . What conclusion can reasonably be drawn about the reaction at this time?

Accepted Answer

A)   K > Q
B)   K 
C)   K = Q
D)   K = 1
E)   Q = 1 F) A) and E)
G) A) and D)

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

The reaction of methane with water to form carbon dioxide and hydrogen is non-spontaneous at 298 K. At what temperature will this system make the transition from non-spontaneous to spontaneous? The data refer to 298 K.

Correct Answer
verified

Correct Answer
verified
The third law specifies the state of zer...
View Answer

You are given pure samples of ammonia, NH₃(g) , and nitrogen trifluoride, NF₃(g) . What prediction would you make concerning their standard molar entropies at 298 K?

Correct Answer
verified

A reaction has a positive value of $\Delta$ H $\degree$ and a positive value of $\Delta$ S $\degree$ . Draw a neat, labeled schematic plot to show how $\Delta$ G $\degree$ (y-axis) will depend on absolute temperature (x-axis).

Correct Answer
verified

The free energy of a perfect crystal at absolute zero, is zero.

Correct Answer
verified

Which relationship or statement best describes $\Delta$ S $\degree$ for the following reaction? 2H₂S(g) + 3O₂(g) $\rightarrow$ 2H₂O(g) + 2SO₂(g)

Correct Answer
verified
B

A reaction has $\Delta$ G= 10.0 kJ and $\Delta$ G $\degree$ = 15.0 kJ at a temperature of 50 $\degree$ C. Calculate the value of the reaction quotient Q under these conditions.

Correct Answer
verified

Correct Answer
verified

Which relationship or statement best describes $\Delta$ S $\degree$ for the following reaction? Pb(s) + Cl₂(g) $\rightarrow$ PbCl₂(s)

Correct Answer
verified

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

Correct Answer
verified

Calculate $\Delta$ S $\degree$ for the reaction $Calculate \Delta S \degree for the reaction A) -254.96 J/K B) -198.02 J/K C) 198.02 J/K D) 254.96 J/K E) 471.86 J/K$ $Calculate \Delta S \degree for the reaction A) -254.96 J/K B) -198.02 J/K C) 198.02 J/K D) 254.96 J/K E) 471.86 J/K$

Correct Answer
verified

You are given pure samples of ethane, C₂H₆(g) , and toluene, C₇H₈(l) . What prediction would you make concerning their standard molar entropies at 298 K?

Correct Answer
verified

Given: H₂O(l) $\rightarrow$ H₂O(s) , $\Delta$ H $\degree$ = -6.02 kJ at 273K, calculate the entropy change of the surroundings ( $\Delta$ S_surr) when one mole of water freezes at 0 $\degree$ C and a pressure of one atmosphere.

Correct Answer
verified

Correct Answer
verified
Relative to graphite and hydrogen, acety...
View Answer

For any reaction, if $\Delta$ G $\degree$ > 0, then K < 1.

Correct Answer
verified

Correct Answer
verified

In a spontaneous process, the entropy of the system always increases.

Correct Answer
verified
False

Which of the following results in a decrease in the entropy of the system?

Correct Answer
verified

Which, if any, of the following processes is spontaneous under the specified conditions?

Correct Answer
verified
B

A reaction is proceeding towards equilibrium. At a certain stage, the concentrations of reactants and products are such that $\Delta$ G = $\Delta$ G $\degree$ . What conclusion can reasonably be drawn about the reaction at this time?

Correct Answer
verified

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

The reaction of methane with water to form carbon dioxide and hydrogen is non-spontaneous at 298 K. At what temperature will this system make the transition from non-spontaneous to spontaneous? The data refer to 298 K.

Correct AnswerverifiedShow Answer

Correct AnswerverifiedThe third law specifies the state of zer...View AnswerShow Answer

You are given pure samples of ammonia, NH3(g) , and nitrogen trifluoride, NF3(g) . What prediction would you make concerning their standard molar entropies at 298 K?

Correct AnswerverifiedShow Answer

A reaction has a positive value of Δ\DeltaΔ H °\degree° and a positive value of Δ\DeltaΔ S °\degree° . Draw a neat, labeled schematic plot to show how Δ\DeltaΔ G °\degree° (y-axis) will depend on absolute temperature (x-axis).

Correct AnswerverifiedShow Answer

The free energy of a perfect crystal at absolute zero, is zero.

Correct AnswerverifiedShow Answer

Which relationship or statement best describes Δ\DeltaΔ S °\degree° for the following reaction? 2H2S(g) + 3O2(g) →\rightarrow→ 2H2O(g) + 2SO2(g)

Correct AnswerverifiedB

A reaction has Δ\DeltaΔ G= 10.0 kJ and Δ\DeltaΔ G °\degree° = 15.0 kJ at a temperature of 50 °\degree° C. Calculate the value of the reaction quotient Q under these conditions.

Correct AnswerverifiedShow Answer

Calculate Δ\DeltaΔ G °\degree° for the combustion of propane.

Correct AnswerverifiedShow Answer

Which relationship or statement best describes Δ\DeltaΔ S °\degree° for the following reaction? Pb(s) + Cl2(g) →\rightarrow→ PbCl2(s)

Correct AnswerverifiedShow Answer

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

Correct AnswerverifiedShow Answer

Calculate Δ\DeltaΔ S °\degree° for the reaction

Correct AnswerverifiedShow Answer

You are given pure samples of ethane, C2H6(g) , and toluene, C7H8(l) . What prediction would you make concerning their standard molar entropies at 298 K?

Correct AnswerverifiedShow Answer

Given: H2O(l) →\rightarrow→ H2O(s) , Δ\DeltaΔ H °\degree° = -6.02 kJ at 273K, calculate the entropy change of the surroundings ( Δ\DeltaΔ Ssurr) when one mole of water freezes at 0 °\degree° C and a pressure of one atmosphere.

Correct AnswerverifiedShow Answer

Correct AnswerverifiedRelative to graphite and hydrogen, acety...View AnswerShow Answer

For any reaction, if Δ\DeltaΔ G °\degree° > 0, then K < 1.

Correct AnswerverifiedShow Answer

What is the free energy change, Δ\DeltaΔ G °\degree° , for the equilibrium between hydrogen iodide, hydrogen, and iodine at 453 °\degree° C? Kc = 0.020

Correct AnswerverifiedShow Answer

In a spontaneous process, the entropy of the system always increases.

Correct AnswerverifiedFalse

Which of the following results in a decrease in the entropy of the system?

Correct AnswerverifiedShow Answer

Which, if any, of the following processes is spontaneous under the specified conditions?

Correct AnswerverifiedB

A reaction is proceeding towards equilibrium. At a certain stage, the concentrations of reactants and products are such that Δ\DeltaΔ G = Δ\DeltaΔ G °\degree° . What conclusion can reasonably be drawn about the reaction at this time?

Correct AnswerverifiedShow Answer

Correct Answer
verified

Correct Answer
verified
The third law specifies the state of zer...
View Answer

You are given pure samples of ammonia, NH₃(g) , and nitrogen trifluoride, NF₃(g) . What prediction would you make concerning their standard molar entropies at 298 K?

Correct Answer
verified

A reaction has a positive value of $\Delta$ H $\degree$ and a positive value of $\Delta$ S $\degree$ . Draw a neat, labeled schematic plot to show how $\Delta$ G $\degree$ (y-axis) will depend on absolute temperature (x-axis).

Correct Answer
verified

Correct Answer
verified

Which relationship or statement best describes $\Delta$ S $\degree$ for the following reaction? 2H₂S(g) + 3O₂(g) $\rightarrow$ 2H₂O(g) + 2SO₂(g)

Correct Answer
verified
B

A reaction has $\Delta$ G= 10.0 kJ and $\Delta$ G $\degree$ = 15.0 kJ at a temperature of 50 $\degree$ C. Calculate the value of the reaction quotient Q under these conditions.

Correct Answer
verified

Correct Answer
verified

Which relationship or statement best describes $\Delta$ S $\degree$ for the following reaction? Pb(s) + Cl₂(g) $\rightarrow$ PbCl₂(s)

Correct Answer
verified

Correct Answer
verified

Calculate $\Delta$ S $\degree$ for the reaction $Calculate \Delta S \degree for the reaction A) -254.96 J/K B) -198.02 J/K C) 198.02 J/K D) 254.96 J/K E) 471.86 J/K$ $Calculate \Delta S \degree for the reaction A) -254.96 J/K B) -198.02 J/K C) 198.02 J/K D) 254.96 J/K E) 471.86 J/K$

Correct Answer
verified

You are given pure samples of ethane, C₂H₆(g) , and toluene, C₇H₈(l) . What prediction would you make concerning their standard molar entropies at 298 K?

Correct Answer
verified

Given: H₂O(l) $\rightarrow$ H₂O(s) , $\Delta$ H $\degree$ = -6.02 kJ at 273K, calculate the entropy change of the surroundings ( $\Delta$ S_surr) when one mole of water freezes at 0 $\degree$ C and a pressure of one atmosphere.

Correct Answer
verified

Correct Answer
verified
Relative to graphite and hydrogen, acety...
View Answer

For any reaction, if $\Delta$ G $\degree$ > 0, then K < 1.

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified
False

Correct Answer
verified

Correct Answer
verified
B

A reaction is proceeding towards equilibrium. At a certain stage, the concentrations of reactants and products are such that $\Delta$ G = $\Delta$ G $\degree$ . What conclusion can reasonably be drawn about the reaction at this time?

Correct Answer
verified