Question 1

What is the equilibrium constant of the reaction at 25°C if ΔG° = 2.8 kJ?
N2O4(g)⇌ 2NO2(g)

Accepted Answer

A) 0.32 
B) 3.1 
C) 1.1 
D) 102.8 
A) 0.32 
B) 3.1 
C) 1.1 
D) 102.8 A

Question 2

If ΔG > 0,which of the following statements is true?

Accepted Answer

A) The reaction is spontaneous. 
B) The reaction is not spontaneous. 
C) The reaction is at equilibrium. 
D) Not enough information is given. 
A) The reaction is spontaneous. 
B) The reaction is not spontaneous. 
C) The reaction is at equilibrium. 
D) Not enough information is given. B

Question 3

Which of the following statements is true?

Accepted Answer

A) There is a "heat tax" for every energy transaction. 
B) A spontaneous reaction is always a fast reaction. 
C) The entropy of a system always decreases for a spontaneous process. 
D) Perpetual motion machines are a possibility in the near future. 
E) None of the above are true. 
A) There is a "heat tax" for every energy transaction. 
B) A spontaneous reaction is always a fast reaction. 
C) The entropy of a system always decreases for a spontaneous process. 
D) Perpetual motion machines are a possibility in the near future. 
E) None of the above are true. A

Question 4

Which of the following is not true for ΔGrxn?

Accepted Answer

A) If ΔG°rxn > 0,the reaction is spontaneous in the forward direction. 
B) If Q = 1,then ΔGrxn = ΔG°rxn. 
C) If ΔG°rxn = 0,the reaction is spontaneous in the reverse direction. 
D) If ΔG°rxn > 0,the reaction is spontaneous in the reverse direction. 
E) Under equilibrium conditions,ΔGrxn = 0. 
A) If ΔG°rxn > 0,the reaction is spontaneous in the forward direction. 
B) If Q = 1,then ΔGrxn = ΔG°rxn. 
C) If ΔG°rxn = 0,the reaction is spontaneous in the reverse direction. 
D) If ΔG°rxn > 0,the reaction is spontaneous in the reverse direction. 
E) Under equilibrium conditions,ΔGrxn = 0.

Question 5

Determine the equilibrium constant for the following reaction at 298 K.
SO3(g)+ H2O(g)→ H2SO4(l)ΔG° = -90.5 kJ

Accepted Answer

A) 1.37 × 10-16 
B) 4.78 × 1011 
C) 9.11 × 10-8 
D) 7.31 × 1015 
E) 0.964 
A) 1.37 × 10-16 
B) 4.78 × 1011 
C) 9.11 × 10-8 
D) 7.31 × 1015 
E) 0.964

Question 6

Calculate the ΔG°rxn using the following information.
4 HNO3(g)+ 5 N2H4(l)→ 7 N2(g)+ 12 H2O(l)ΔG°rxn = ?
ΔH°f (kJ/mol)-133.9 50.6 -285.8
S°(J/mol∙K)266.9 121.2 191.6 70.0

Accepted Answer

A) +4.90 × 103 kJ 
B) +3.90 × 103 kJ 
C) -2.04 × 103 kJ 
D) -3.15 × 103 kJ 
E) -3.298 × 103 kJ 
A) +4.90 × 103 kJ 
B) +3.90 × 103 kJ 
C) -2.04 × 103 kJ 
D) -3.15 × 103 kJ 
E) -3.298 × 103 kJ

Question 7

Calculate ΔS°rxn for the following reaction.The S° for each species is shown below the reaction.
N2H4(l)+ H2(g)→ 2 NH3(g)
S° (J/mol∙K)121.2 130.7 192.8

Accepted Answer

A) +133.7 J/K 
B) -59.1 J/K 
C) +118.2 J/K 
D) -202.3 J/K 
E) +178.9 J/K 
A) +133.7 J/K 
B) -59.1 J/K 
C) +118.2 J/K 
D) -202.3 J/K 
E) +178.9 J/K

Question 8

Calculate ΔS°rxn for the following reaction.The S° for each species is shown below the reaction.
4 NH3(g)+ 5 O2(g)→ 4 NO(g)+ 6 H2O(g)
S°(J/mol∙K)192.8 205.2 210.8 188.8

Accepted Answer

A) +287.4 J/K 
B) -401.2 J/K 
C) +160.0 J/K 
D) -336.6 J/K 
E) +178.8 J/K 
A) +287.4 J/K 
B) -401.2 J/K 
C) +160.0 J/K 
D) -336.6 J/K 
E) +178.8 J/K

Question 9

Place the following in order of decreasing standard molar entropy.
NaCl(s)Na3PO4(aq)NaCl(aq)

Accepted Answer

A) NaCl(s)> NaCl(aq)> Na3PO4(aq) 
B) NaCl(aq)> NaCl(s)> Na3PO4(aq) 
C) Na3PO4(aq)> NaCl(aq)> NaCl(s) 
D) NaCl(s)> Na3PO4(aq)> NaCl(aq) 
E) NaCl(aq)> Na3PO4(aq)> NaCl(s) 
A) NaCl(s)> NaCl(aq)> Na3PO4(aq) 
B) NaCl(aq)> NaCl(s)> Na3PO4(aq) 
C) Na3PO4(aq)> NaCl(aq)> NaCl(s) 
D) NaCl(s)> Na3PO4(aq)> NaCl(aq) 
E) NaCl(aq)> Na3PO4(aq)> NaCl(s)

Question 10

Which one of the following has the highest standard molar entropy,S°,at 25°C?

Accepted Answer

A) I2(g) 
B) F2(g) 
C) Br2(l) 
D) O2(g) 
E) Cl2(g) 
A) I2(g) 
B) F2(g) 
C) Br2(l) 
D) O2(g) 
E) Cl2(g)

Question 11

Identify the change in state where ΔS decreases.

Accepted Answer

A) solid to liquid 
B) liquid to gas 
C) solid to gas 
D) gas to solid 
A) solid to liquid 
B) liquid to gas 
C) solid to gas 
D) gas to solid

Question 12

Which of the following processes has a ΔS > 0?

Accepted Answer

A) 2 NH3(g)+ CO2(g)→ NH2CONH2(aq)+ H2O(l) 
B) Lithium fluoride forms from its elements. 
C) 2 HBr(g)→ H2(g)+ Br2(l) 
D) Sodium chloride dissolves in pure water. 
E) All of the above processes have a DS > 0. 
A) 2 NH3(g)+ CO2(g)→ NH2CONH2(aq)+ H2O(l) 
B) Lithium fluoride forms from its elements. 
C) 2 HBr(g)→ H2(g)+ Br2(l) 
D) Sodium chloride dissolves in pure water. 
E) All of the above processes have a DS > 0.

Question 13

The value of ΔG° at 141.0 °C for the formation of phosphorous trichloride from its constituent elements,
P2(g)+ 3Cl2(g)→ 2PCl3(g)
Is ________ kJ/mol.At 25.0°C for this reaction,ΔH° is -720.5 kJ/mol,ΔG° is -642.9 kJ/mol,and ΔS° is
-263.7 J/K.

Accepted Answer

A) -612.3 
B) 3.65 × 104 
C) 1.08 × 105 
D) -683.3 
E) -829.7 
A) -612.3 
B) 3.65 × 104 
C) 1.08 × 105 
D) -683.3 
E) -829.7

Question 14

Estimate ΔG°rxn for the following reaction at 417 K.
HCN(g)+ 2 H2(g)→ CH3NH2(g)ΔH°= -158.0 kJ;ΔS°= -219.9 J/K

Accepted Answer

A) +61.9 kJ 
B) -66.3 kJ 
C) +66.3 kJ 
D) -250 kJ 
E) +250 kJ 
A) +61.9 kJ 
B) -66.3 kJ 
C) +66.3 kJ 
D) -250 kJ 
E) +250 kJ

Question 15

In the Haber process,ammonia is synthesized from nitrogen and hydrogen:
N2(g)+ 3H2(g)→ 2NH3(g)
ΔG° at 298 K for this reaction is -33.3 kJ/mol.The value of ΔG at 298 K for a reaction mixture that consists of 1.9 atm N2,1.6 atm H2,and 0.65 atm NH3 is ________.

Accepted Answer

A) -1.8 
B) -3.86 × 103 
C) -7.25 × 103  
D) -104.5 
E) -40.5 
A) -1.8 
B) -3.86 × 103 
C) -7.25 × 103  
D) -104.5 
E) -40.5

Question 16

Consider the following reaction at constant P.Use the information here to determine the value of ΔSsurr at 298 K.Predict whether or not this reaction will be spontaneous at this temperature.
N2(g)+ 2 O2(g)→ 2 NO2(g)ΔH = +66.4 kJ

Accepted Answer

A) ΔSsurr = +223 J/K,reaction is spontaneous 
B) ΔSsurr = -223 J/K,reaction is not spontaneous 
C) ΔSsurr = -66.4 J/K,reaction is spontaneous 
D) ΔSsurr = +66.4 kJ/K,reaction is not spontaneous 
E) ΔSsurr = -66.4 J/K,it is not possible to predict the spontaneity of this reaction without more information. 
A) ΔSsurr = +223 J/K,reaction is spontaneous 
B) ΔSsurr = -223 J/K,reaction is not spontaneous 
C) ΔSsurr = -66.4 J/K,reaction is spontaneous 
D) ΔSsurr = +66.4 kJ/K,reaction is not spontaneous 
E) ΔSsurr = -66.4 J/K,it is not possible to predict the spontaneity of this reaction without more information.

Question 17

Consider the following reaction at constant P.Use the information here to determine the value of ΔSsurr at 398 K.Predict whether or not this reaction will be spontaneous at this temperature.
4 NH3(g)+ 3 O2(g)→ 2 N2(g)+ 6 H2O(g)ΔH = -1267 kJ

Accepted Answer

A) ΔSsurr = +12.67 kJ/K,reaction is not spontaneous 
B) ΔSsurr = -12.67 kJ/K,reaction is spontaneous 
C) ΔSsurr = +50.4 kJ/K,reaction is not spontaneous 
D) ΔSsurr = +3.18 kJ/K,reaction is spontaneous 
E) ΔSsurr = -3.18 kJ/K,it is not possible to predict the spontaneity of this reaction without more information. 
A) ΔSsurr = +12.67 kJ/K,reaction is not spontaneous 
B) ΔSsurr = -12.67 kJ/K,reaction is spontaneous 
C) ΔSsurr = +50.4 kJ/K,reaction is not spontaneous 
D) ΔSsurr = +3.18 kJ/K,reaction is spontaneous 
E) ΔSsurr = -3.18 kJ/K,it is not possible to predict the spontaneity of this reaction without more information.

Question 18

Calculate ΔGrxn at 298 K under the conditions shown below for the following reaction.
Fe2O3(s)+ 3 CO(g)→ 2 Fe(s)+ 3 CO2(g)ΔG° = -28.0 kJ
P(CO)= 1.4 atm,P(CO2)= 2.1 atm

Accepted Answer

A) +31.0 kJ 
B) +2.99 kJ 
C) -30.7 kJ 
D) +17.5 kJ 
E) -25.0 kJ 
A) +31.0 kJ 
B) +2.99 kJ 
C) -30.7 kJ 
D) +17.5 kJ 
E) -25.0 kJ

Question 19

Place the following in order of increasing entropy at 298 K.
Ne Xe He Ar Kr

Accepted Answer

A) He < Kr < Ne < Ar < Xe 
B) Xe < Kr < Ar < Ne < He 
C) Ar < He < Ar < Ne < Kr 
D) Ar < Ne < Xe < Kr < He 
E) He < Ne < Ar < Kr < Xe 
A) He < Kr < Ne < Ar < Xe 
B) Xe < Kr < Ar < Ne < He 
C) Ar < He < Ar < Ne < Kr 
D) Ar < Ne < Xe < Kr < He 
E) He < Ne < Ar < Kr < Xe

Question 20

Place the following in order of increasing standard molar entropy.
H2O(l)H2O(g)H2O(s)

Accepted Answer

A) H2O(g)2O(l)2O(s) 
B) H2O(s)2O(l)2O(g) 
C) H2O(g)2O(s)2O(l) 
D) H2O(l)2O(s)2O(g) 
E) H2O(s)2O(g)2O(l) 
A) H2O(g)2O(l)2O(s) 
B) H2O(s)2O(l)2O(g) 
C) H2O(g)2O(s)2O(l) 
D) H2O(l)2O(s)2O(g) 
E) H2O(s)2O(g)2O(l)

What is the equilibrium constant of the reaction at 25°C if ΔG° = 2.8 kJ? N₂O₄(g)⇌ 2NO₂(g)

If ΔG > 0,which of the following statements is true?

Which of the following statements is true?

Which of the following is not true for ΔG_rxn?

Determine the equilibrium constant for the following reaction at 298 K. SO₃(g)+ H₂O(g)→ H₂SO₄(l)ΔG° = -90.5 kJ

Calculate the ΔG°_rxn using the following information. 4 HNO₃(g)+ 5 N₂H₄(l)→ 7 N₂(g)+ 12 H₂O(l)ΔG°_rxn= ? ΔH°_f (kJ/mol)-133.9 50.6 -285.8 S°(J/mol^∙K)266.9 121.2 191.6 70.0

Calculate ΔS°_rxn for the following reaction.The S° for each species is shown below the reaction. N₂H₄(l)+ H₂(g)→ 2 NH₃(g) S° (J/mol^∙K)121.2 130.7 192.8

Calculate ΔS°_rxn for the following reaction.The S° for each species is shown below the reaction. 4 NH₃(g)+ 5 O₂(g)→ 4 NO(g)+ 6 H₂O(g) S°(J/mol^∙K)192.8 205.2 210.8 188.8

Place the following in order of decreasing standard molar entropy. NaCl(s)Na₃PO₄(aq)NaCl(aq)

Which one of the following has the highest standard molar entropy,S°,at 25°C?

Identify the change in state where ΔS decreases.

Which of the following processes has a ΔS > 0?

The value of ΔG° at 141.0 °C for the formation of phosphorous trichloride from its constituent elements, P₂(g)+ 3Cl₂(g)→ 2PCl₃(g) Is ________ kJ/mol.At 25.0°C for this reaction,ΔH° is -720.5 kJ/mol,ΔG° is -642.9 kJ/mol,and ΔS° is -263.7 J/K.

Estimate ΔG°_rxn for the following reaction at 417 K. HCN(g)+ 2 H₂(g)→ CH₃NH₂(g)ΔH°= -158.0 kJ;ΔS°= -219.9 J/K

In the Haber process,ammonia is synthesized from nitrogen and hydrogen: N₂(g)+ 3H₂(g)→ 2NH₃(g) ΔG° at 298 K for this reaction is -33.3 kJ/mol.The value of ΔG at 298 K for a reaction mixture that consists of 1.9 atm N₂,1.6 atm H₂,and 0.65 atm NH₃ is ________.

Consider the following reaction at constant P.Use the information here to determine the value of ΔS_surrat 298 K.Predict whether or not this reaction will be spontaneous at this temperature. N₂(g)+ 2 O₂(g)→ 2 NO₂(g)ΔH = +66.4 kJ

Consider the following reaction at constant P.Use the information here to determine the value of ΔS_surr at 398 K.Predict whether or not this reaction will be spontaneous at this temperature. 4 NH₃(g)+ 3 O₂(g)→ 2 N₂(g)+ 6 H₂O(g)ΔH = -1267 kJ

Calculate ΔG_rxn at 298 K under the conditions shown below for the following reaction. Fe₂O₃(s)+ 3 CO(g)→ 2 Fe(s)+ 3 CO₂(g)ΔG° = -28.0 kJ P(CO)= 1.4 atm,P(CO₂)= 2.1 atm

Place the following in order of increasing entropy at 298 K. Ne Xe He Ar Kr

Place the following in order of increasing standard molar entropy. H₂O(l)H₂O(g)H₂O(s)

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Exam 17: Free Energy and Thermodynamics

What is the equilibrium constant of the reaction at 25°C if ΔG° = 2.8 kJ? N2O4(g)⇌ 2NO2(g)

If ΔG > 0,which of the following statements is true?

Which of the following statements is true?

Which of the following is not true for ΔGrxn?

Determine the equilibrium constant for the following reaction at 298 K. SO3(g)+ H2O(g)→ H2SO4(l)ΔG° = -90.5 kJ

Calculate the ΔG°rxn using the following information. 4 HNO3(g)+ 5 N2H4(l)→ 7 N2(g)+ 12 H2O(l)ΔG°rxn = ? ΔH°f (kJ/mol)-133.9 50.6 -285.8 S°(J/mol∙K)266.9 121.2 191.6 70.0

Calculate ΔS°rxn for the following reaction.The S° for each species is shown below the reaction. N2H4(l)+ H2(g)→ 2 NH3(g) S° (J/mol∙K)121.2 130.7 192.8

Calculate ΔS°rxn for the following reaction.The S° for each species is shown below the reaction. 4 NH3(g)+ 5 O2(g)→ 4 NO(g)+ 6 H2O(g) S°(J/mol∙K)192.8 205.2 210.8 188.8

Place the following in order of decreasing standard molar entropy. NaCl(s)Na3PO4(aq)NaCl(aq)

Which one of the following has the highest standard molar entropy,S°,at 25°C?

Identify the change in state where ΔS decreases.

Which of the following processes has a ΔS > 0?

The value of ΔG° at 141.0 °C for the formation of phosphorous trichloride from its constituent elements, P2(g)+ 3Cl2(g)→ 2PCl3(g) Is ________ kJ/mol.At 25.0°C for this reaction,ΔH° is -720.5 kJ/mol,ΔG° is -642.9 kJ/mol,and ΔS° is -263.7 J/K.

Estimate ΔG°rxn for the following reaction at 417 K. HCN(g)+ 2 H2(g)→ CH3NH2(g)ΔH°= -158.0 kJ;ΔS°= -219.9 J/K

In the Haber process,ammonia is synthesized from nitrogen and hydrogen: N2(g)+ 3H2(g)→ 2NH3(g) ΔG° at 298 K for this reaction is -33.3 kJ/mol.The value of ΔG at 298 K for a reaction mixture that consists of 1.9 atm N2,1.6 atm H2,and 0.65 atm NH3 is ________.

Consider the following reaction at constant P.Use the information here to determine the value of ΔSsurr at 298 K.Predict whether or not this reaction will be spontaneous at this temperature. N2(g)+ 2 O2(g)→ 2 NO2(g)ΔH = +66.4 kJ

Consider the following reaction at constant P.Use the information here to determine the value of ΔSsurr at 398 K.Predict whether or not this reaction will be spontaneous at this temperature. 4 NH3(g)+ 3 O2(g)→ 2 N2(g)+ 6 H2O(g)ΔH = -1267 kJ

Calculate ΔGrxn at 298 K under the conditions shown below for the following reaction. Fe2O3(s)+ 3 CO(g)→ 2 Fe(s)+ 3 CO2(g)ΔG° = -28.0 kJ P(CO)= 1.4 atm,P(CO2)= 2.1 atm

Place the following in order of increasing entropy at 298 K. Ne Xe He Ar Kr

Place the following in order of increasing standard molar entropy. H2O(l)H2O(g)H2O(s)

Matter, Measurement, and Problem Solving

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What is the equilibrium constant of the reaction at 25°C if ΔG° = 2.8 kJ? N₂O₄(g)⇌ 2NO₂(g)

Which of the following is not true for ΔG_rxn?

Determine the equilibrium constant for the following reaction at 298 K. SO₃(g)+ H₂O(g)→ H₂SO₄(l)ΔG° = -90.5 kJ

Calculate the ΔG°_rxn using the following information. 4 HNO₃(g)+ 5 N₂H₄(l)→ 7 N₂(g)+ 12 H₂O(l)ΔG°_rxn= ? ΔH°_f (kJ/mol)-133.9 50.6 -285.8 S°(J/mol^∙K)266.9 121.2 191.6 70.0

Calculate ΔS°_rxn for the following reaction.The S° for each species is shown below the reaction. N₂H₄(l)+ H₂(g)→ 2 NH₃(g) S° (J/mol^∙K)121.2 130.7 192.8

Calculate ΔS°_rxn for the following reaction.The S° for each species is shown below the reaction. 4 NH₃(g)+ 5 O₂(g)→ 4 NO(g)+ 6 H₂O(g) S°(J/mol^∙K)192.8 205.2 210.8 188.8

Place the following in order of decreasing standard molar entropy. NaCl(s)Na₃PO₄(aq)NaCl(aq)

The value of ΔG° at 141.0 °C for the formation of phosphorous trichloride from its constituent elements, P₂(g)+ 3Cl₂(g)→ 2PCl₃(g) Is ________ kJ/mol.At 25.0°C for this reaction,ΔH° is -720.5 kJ/mol,ΔG° is -642.9 kJ/mol,and ΔS° is -263.7 J/K.

Estimate ΔG°_rxn for the following reaction at 417 K. HCN(g)+ 2 H₂(g)→ CH₃NH₂(g)ΔH°= -158.0 kJ;ΔS°= -219.9 J/K

In the Haber process,ammonia is synthesized from nitrogen and hydrogen: N₂(g)+ 3H₂(g)→ 2NH₃(g) ΔG° at 298 K for this reaction is -33.3 kJ/mol.The value of ΔG at 298 K for a reaction mixture that consists of 1.9 atm N₂,1.6 atm H₂,and 0.65 atm NH₃ is ________.

Consider the following reaction at constant P.Use the information here to determine the value of ΔS_surrat 298 K.Predict whether or not this reaction will be spontaneous at this temperature. N₂(g)+ 2 O₂(g)→ 2 NO₂(g)ΔH = +66.4 kJ

Consider the following reaction at constant P.Use the information here to determine the value of ΔS_surr at 398 K.Predict whether or not this reaction will be spontaneous at this temperature. 4 NH₃(g)+ 3 O₂(g)→ 2 N₂(g)+ 6 H₂O(g)ΔH = -1267 kJ

Calculate ΔG_rxn at 298 K under the conditions shown below for the following reaction. Fe₂O₃(s)+ 3 CO(g)→ 2 Fe(s)+ 3 CO₂(g)ΔG° = -28.0 kJ P(CO)= 1.4 atm,P(CO₂)= 2.1 atm

Place the following in order of increasing standard molar entropy. H₂O(l)H₂O(g)H₂O(s)