Question 1

For the following example, what is true about ΔrH and ΔrS? H2O(l)  → H2O(s)

Accepted Answer

A)   a negative ΔrH and a negative ΔrS
B)   a positive ΔrH and a negative ΔrS
C)   a negative ΔrH and a positive ΔrS
D)   a positive ΔrH and a positive ΔrS
E)   ΔrH = 0 and a positive ΔrS

Question 2

Which of the following is true for ΔrG?

Accepted Answer

A)   If ΔrG > 0, the reaction is spontaneous in the forward direction.
B)   If Q = 1, then DrG > ΔrG.
C)   If ΔrG ≠ 0, the reaction is spontaneous in both the reverse and forward directions.
D)   If ΔrG 
E)   Under equilibrium conditions, ΔrG = 0.

Question 3

Under which of the following conditions would one mole of He have the highest entropy, S?

Accepted Answer

A)   17 °C and 15 L
B)   127 °C and 15 L
C)   17 °C and 25 L
D)   127 °C and 25 L

Question 4

Calculate ΔrS° for the following reaction. The S° for each species is shown below the reaction. C2H2(g)  + H2(g)  → C2H4(g) 
S°(J J K-1 mol-1)  200.9 130.7 219.3

Accepted Answer

A)   +112.3 J K-1 mol-1
B)   +550.9 J K-1 mol-1
C)   -112.3 J K-1 mol-1
D)   +337.1 J K-1 mol-1
E)   -550.9 J K-1 mol-1

Question 5

Determine the Q of a reaction at 298 K if ΔrG = -3.5 kJ mol-1 and ΔrG° = +19.3 kJ mol-1.

Accepted Answer

A)   0.10
B)   0.0010
C)   0.00010
D)   0.34
E)   0.89

Question 6

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

Accepted Answer

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

Question 7

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

Accepted Answer

A)   NH3(g) 
B)   Ne(g) 
C)   SO2(g) 
D)   CH3CH2OH(g) 
E)   He (g)

Question 8

Which one of the following would be expected to have the lowest standard molar entropy, S°, at 25 °C?

Accepted Answer

A)   C10H22(s) 
B)   C10H22(l) 
C)   C14H30(s) 
D)   C14   10H22(s)  
B)   C10H22(l)  
C)   C14H30(s)  
D)   C14     OH(l) " class="answers-bank-image d-inline" rel="preload" > OH(l)

Question 9

Calculate the equilibrium constant for the following reaction at 525 K: 2H2S(g)  → 2H2(g)  + S2(g)  ΔrH° = 169.8 kJ mol-1; ΔrS°= 78.0 J K-1 mol-1

Accepted Answer

A)   3.84 × 10-11
B)   1.51 × 10-13
C)   4.08 × 10-17
D)   7.52 × 10-19
E)   6.18 × 10-15

Question 10

Use the following thermodynamic values to calculate Δr NEWLINE r NEWLINE   . Δr     = -95 kJ   , Δr     = -157 J   , T = 855 K A)  -48 kJ   B)  -68 kJ   C)  +39 kJ   D)  -157 kJ   E)  +142 kJ  " class="answers-bank-image d-inline" rel="preload" > .
Δr
  r NEWLINE   . Δr     = -95 kJ   , Δr     = -157 J   , T = 855 K A)  -48 kJ   B)  -68 kJ   C)  +39 kJ   D)  -157 kJ   E)  +142 kJ  " class="answers-bank-image d-inline" rel="preload" > = -95 kJ r NEWLINE   . Δr     = -95 kJ   , Δr     = -157 J   , T = 855 K A)  -48 kJ   B)  -68 kJ   C)  +39 kJ   D)  -157 kJ   E)  +142 kJ  " class="answers-bank-image d-inline" rel="preload" > , Δr
  r NEWLINE   . Δr     = -95 kJ   , Δr     = -157 J   , T = 855 K A)  -48 kJ   B)  -68 kJ   C)  +39 kJ   D)  -157 kJ   E)  +142 kJ  " class="answers-bank-image d-inline" rel="preload" > = -157 J r NEWLINE   . Δr     = -95 kJ   , Δr     = -157 J   , T = 855 K A)  -48 kJ   B)  -68 kJ   C)  +39 kJ   D)  -157 kJ   E)  +142 kJ  " class="answers-bank-image d-inline" rel="preload" > , T = 855 K

Accepted Answer

A)   -48 kJ r NEWLINE   . Δr     = -95 kJ   , Δr     = -157 J   , T = 855 K 
A)   -48 kJ   
B)   -68 kJ   
C)   +39 kJ   
D)   -157 kJ   
E)   +142 kJ  " class="answers-bank-image d-inline" rel="preload" >
B)   -68 kJ r NEWLINE   . Δr     = -95 kJ   , Δr     = -157 J   , T = 855 K 
A)   -48 kJ   
B)   -68 kJ   
C)   +39 kJ   
D)   -157 kJ   
E)   +142 kJ  " class="answers-bank-image d-inline" rel="preload" >
C)   +39 kJ r NEWLINE   . Δr     = -95 kJ   , Δr     = -157 J   , T = 855 K 
A)   -48 kJ   
B)   -68 kJ   
C)   +39 kJ   
D)   -157 kJ   
E)   +142 kJ  " class="answers-bank-image d-inline" rel="preload" >
D)   -157 kJ r NEWLINE   . Δr     = -95 kJ   , Δr     = -157 J   , T = 855 K 
A)   -48 kJ   
B)   -68 kJ   
C)   +39 kJ   
D)   -157 kJ   
E)   +142 kJ  " class="answers-bank-image d-inline" rel="preload" >
E)   +142 kJ r NEWLINE   . Δr     = -95 kJ   , Δr     = -157 J   , T = 855 K 
A)   -48 kJ   
B)   -68 kJ   
C)   +39 kJ   
D)   -157 kJ   
E)   +142 kJ  " class="answers-bank-image d-inline" rel="preload" >

Question 11

Above what temperature does the following reaction become nonspontaneous? 2H2S(g)  + 3O2(g)  → 2SO2(g)  + 2H2O(g)  ΔrH = -1036 kJ; ΔrS = -153.2 J K-1 mol-1

Accepted Answer

A)   6.762 × 103 K
B)   158.7 K
C)   298 K
D)   67.62 K
E)   1.587 × 103 K

Question 12

Match the following.
-Q = K

Accepted Answer

A)  standard state
B)  equilibrium
C)  ΔrG > ΔrG°
D)  ΔrG > 0
E)  DrG F) K = 0G) ΔrG rG°

Question 13

Calculate ΔrG for the evaporation of methanol at 25°C under nonstandard conditions when rG for the evaporation of methanol at 25°C under nonstandard conditions when   = 150.0 mbar CH3OH(l)  → CH3OH(g)  A)  -0.40 kJ mol-1 B)  +9.0 kJ mol-1 C)  -0.47 kJ mol-1 D)  +4.3 kJ mol-1 E)  +16 kJ mol-1" class="answers-bank-image d-inline" rel="preload" > = 150.0 mbar CH3OH(l)  → CH3OH(g)

Accepted Answer

A)   -0.40 kJ mol-1
B)   +9.0 kJ mol-1
C)   -0.47 kJ mol-1
D)   +4.3 kJ mol-1
E)   +16 kJ mol-1

Question 14

Calculate ΔrS° for the following reaction. The S° for each species is shown below the reaction. N2H4(l)  + H2(g)  → 2NH3(g) 
S° (J K-1 mol-1)  121.2 130.7 192.8

Accepted Answer

A)   +133.7 J K-1 mol-1
B)   -59.1 J K-1 mol-1
C)   +118.2 J K-1 mol-1
D)   -202.3 J K-1 mol-1
E)   +178.9 J K-1 mol-1

Question 15

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

Accepted Answer

A)   H2(g) 
B)   F2(g) 
C)   O2(g) 
D)   N2(g) 
E)   Cl2(g)

Question 16

Calculate the equilibrium constant for the following reaction at 525 K: 2CO(g)  + O2(g)  → 2CO2(g)  ΔrH° = -566 kJ mol-1; ΔrS°= -173 J K-1 mol-1

Accepted Answer

A)   3.61 × 1058
B)   1.90 × 1047
C)   2.47 × 1014
D)   7.56 × 1084
E)   8.49 × 106

Question 17

Determine ΔrG° at 298 K using the following information: 2KClO3(s)  → 2KCl(s)  + 3O2(g)  ΔrH°= -77.6 kJ mol-1; ΔrS°= +494.6 J K-1 mol-1

Accepted Answer

A)   -225.0 kJ mol-1
B)   +68.4 .0 kJ mol-1
C)   -89.3 kJ mol-1
D)   +131.5 kJ mol-1
E)   +175.2 kJ mol-1

Question 18

Determine the equilibrium constant for the following reaction at 655 K: HCN(g)  + 2H2(g)  → CH3NH2(g)  ΔrH° = -158 kJ mol-1; ΔrS°= -219.9 J K-1 mol-1

Accepted Answer

A)   3.99 × 1012
B)   13.0
C)   2.51 × 10-13
D)   3.26 × 10-12
E)   3.07 × 1011

Question 19

For a given reaction, ΔrH = -19.5 kJ mol-1 and ΔrS = -55.8 J K-1 mol-1. The reaction will have rH = -19.5 kJ mol-1 and ΔrS = -55.8 J K-1 mol-1. The reaction will have   at   Assume that ΔrH and ΔrS do not vary with temperature. A)  2.86 B)  0.349 C)  298 D)  2.86 × 103 E)  349" class="answers-bank-image d-inline" rel="preload" > at rH = -19.5 kJ mol-1 and ΔrS = -55.8 J K-1 mol-1. The reaction will have   at   Assume that ΔrH and ΔrS do not vary with temperature. A)  2.86 B)  0.349 C)  298 D)  2.86 × 103 E)  349" class="answers-bank-image d-inline" rel="preload" > Assume that ΔrH and ΔrS do not vary with temperature.

Accepted Answer

A)   2.86
B)   0.349
C)   298
D)   2.86 × 103
E)   349

Question 20

What is "free" energy? Give a fictitious example.

Accepted Answer

Consider a reaction that is exothermic (...

Exam 17: Gibbs Energy and Thermodynamics

Which one of the following would be expected to have the lowest standard molar entropy, S°, at 25 °C?

Correct AnswerverifiedShow Answer

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

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Which of the following is true for ΔrG?

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Calculate ΔrG for the evaporation of methanol at 25°C under nonstandard conditions when = 150.0 mbar CH3OH(l) → CH3OH(g)

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

Correct AnswerverifiedShow Answer

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

Correct AnswerverifiedShow Answer

For the following example, what is true about ΔrH and ΔrS? H2O(l) → H2O(s)

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Calculate the equilibrium constant for the following reaction at 525 K: 2H2S(g) → 2H2(g) + S2(g) ΔrH° = 169.8 kJ mol-1; ΔrS°= 78.0 J K-1 mol-1

Correct AnswerverifiedShow Answer

Calculate ΔrS° for the following reaction. The S° for each species is shown below the reaction. N2H4(l) + H2(g) → 2NH3(g) S° (J K-1 mol-1) 121.2 130.7 192.8

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Use the following thermodynamic values to calculate Δr NEWLINE . Δr = -95 kJ , Δr = -157 J , T = 855 K

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Calculate the equilibrium constant for the following reaction at 525 K: 2CO(g) + O2(g) → 2CO2(g) ΔrH° = -566 kJ mol-1; ΔrS°= -173 J K-1 mol-1

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Above what temperature does the following reaction become nonspontaneous? 2H2S(g) + 3O2(g) → 2SO2(g) + 2H2O(g) ΔrH = -1036 kJ; ΔrS = -153.2 J K-1 mol-1

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Determine the equilibrium constant for the following reaction at 655 K: HCN(g) + 2H2(g) → CH3NH2(g) ΔrH° = -158 kJ mol-1; ΔrS°= -219.9 J K-1 mol-1

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Determine the Q of a reaction at 298 K if ΔrG = -3.5 kJ mol-1 and ΔrG° = +19.3 kJ mol-1.

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Determine ΔrG° at 298 K using the following information: 2KClO3(s) → 2KCl(s) + 3O2(g) ΔrH°= -77.6 kJ mol-1; ΔrS°= +494.6 J K-1 mol-1

Correct AnswerverifiedShow Answer

Match the following. -Q = K

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What is "free" energy? Give a fictitious example.

Correct AnswerverifiedConsider a reaction that is exothermic (...View AnswerShow Answer

For a given reaction, ΔrH = -19.5 kJ mol-1 and ΔrS = -55.8 J K-1 mol-1. The reaction will have at Assume that ΔrH and ΔrS do not vary with temperature.

Correct AnswerverifiedShow Answer

Under which of the following conditions would one mole of He have the highest entropy, S?

Correct AnswerverifiedShow Answer

Calculate ΔrS° for the following reaction. The S° for each species is shown below the reaction. C2H2(g) + H2(g) → C2H4(g) S°(J J K-1 mol-1) 200.9 130.7 219.3

Correct AnswerverifiedShow Answer

Correct Answer
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Correct Answer
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Which of the following is true for Δ_rG?

Correct Answer
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Calculate Δ_rG for the evaporation of methanol at 25°C under nonstandard conditions when = 150.0 mbar CH₃OH(l) → CH₃OH(g)

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Correct Answer
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For the following example, what is true about Δ_rH and Δ_rS? H₂O(l) → H₂O(s)

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Calculate the equilibrium constant for the following reaction at 525 K: 2H₂S(g) → 2H₂(g) + S₂(g) Δ_rH° = 169.8 kJ mol^-1; Δ_rS°= 78.0 J K^-1 mol^-1

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Calculate Δ_rS° for the following reaction. The S° for each species is shown below the reaction. N₂H₄(l) + H₂(g) → 2NH₃(g) S° (J K^-1 mol^-1) 121.2 130.7 192.8

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Use the following thermodynamic values to calculate Δ_r _NE_WLINE . Δ_r = -95 kJ , Δ_r = -157 J , T = 855 K

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Calculate the equilibrium constant for the following reaction at 525 K: 2CO(g) + O₂(g) → 2CO₂(g) Δ_rH° = -566 kJ mol^-1; Δ_rS°= -173 J K^-1 mol^-1

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Above what temperature does the following reaction become nonspontaneous? 2H₂S(g) + 3O₂(g) → 2SO₂(g) + 2H₂O(g) Δ_rH = -1036 kJ; Δ_rS = -153.2 J K^-1 mol^-1

Correct Answer
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Determine the equilibrium constant for the following reaction at 655 K: HCN(g) + 2H₂(g) → CH₃NH₂(g) Δ_rH° = -158 kJ mol^-1; Δ_rS°= -219.9 J K^-1 mol^-1

Correct Answer
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Determine the Q of a reaction at 298 K if Δ_rG = -3.5 kJ mol^-1 and Δ_rG° = +19.3 kJ mol^-1.

Correct Answer
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Determine Δ_rG° at 298 K using the following information: 2KClO₃(s) → 2KCl(s) + 3O₂(g) Δ_rH°= -77.6 kJ mol^-1; Δ_rS°= +494.6 J K^-1 mol^-¹

Correct Answer
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Correct Answer
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Correct Answer
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Consider a reaction that is exothermic (...
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For a given reaction, Δ_rH = -19.5 kJ mol^-1 and Δ_rS = -55.8 J K^-¹ mol^-1. The reaction will have at Assume that Δ_rH and Δ_rS do not vary with temperature.

Correct Answer
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Correct Answer
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Calculate Δ_rS° for the following reaction. The S° for each species is shown below the reaction. C₂H₂(g) + H₂(g) → C₂H₄(g) S°(J J K^-1 mol^-1) 200.9 130.7 219.3

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