Question 1

Above what temperature does the following reaction become nonspontaneous? FeO(s) + CO(g) → CO2(g) + Fe(s) ΔrH = -11.0 kJ; ΔrS = -17.4 J K-1 mol-1

Accepted Answer

A)  632 K 
B)  298 K 
C)  191 K 
D)  6.32 × 103 K 
E)  0 K 
A)  632 K 
B)  298 K 
C)  191 K 
D)  6.32 × 103 K 
E)  0 K

Question 2

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

Accepted Answer

A)  I2(s) 
B)  F2(g) 
C)  Br2(l) 
D)  N2(g) 
E)  Cl2(g) 
A)  I2(s) 
B)  F2(g) 
C)  Br2(l) 
D)  N2(g) 
E)  Cl2(g)

Question 3

For the following example, what is true about ΔrH and ΔrS? 3O2(g) → 2O3(g)

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 
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 4

Calculate ΔrG° at 298 K using the following information: 4HNO3(g) + 5N2H4(l) → 7N2(g) + 12H2O(l) ΔrG° = ?
ΔfH° (kJ mol-1) -133.9 50.6 -285.8
S°(J K-1 mol-1) 266.9 121.2 191.6 70.0

Accepted Answer

A)  +4.90 × 103 kJ mol-1 
B)  +3.90 × 103 kJ mol-1 
C)  -2.04 × 103 kJ mol-1 
D)  -3.15 × 103 kJ mol-1 
E)  -3.30 × 103 kJ mol-1 
A)  +4.90 × 103 kJ mol-1 
B)  +3.90 × 103 kJ mol-1 
C)  -2.04 × 103 kJ mol-1 
D)  -3.15 × 103 kJ mol-1 
E)  -3.30 × 103 kJ mol-1

Question 5

Which of the following statements is TRUE?

Accepted Answer

A)  Entropy is not a state function. 
B)  Endothermic processes decrease the entropy of the surroundings, at constant T and P. 
C)  Endothermic processes are never spontaneous. 
D)  Exothermic processes are always spontaneous. 
E)  Entropy of the universe is a constant value. 
A)  Entropy is not a state function. 
B)  Endothermic processes decrease the entropy of the surroundings, at constant T and P. 
C)  Endothermic processes are never spontaneous. 
D)  Exothermic processes are always spontaneous. 
E)  Entropy of the universe is a constant value.

Question 6

Calculate ΔrG° at 298 K using the following information: 4HNO3(g) + 5N2H4(l) → 7N2(g) + 12H2O(l) ΔrG° = ?
ΔfG° (kJ mol-1) -73.5 149.3 -237.1

Accepted Answer

A)  -3.2977 × 103 kJ mol-1 
B)  -312.9 kJ mol-1 
C)  +2.845 × 103 kJ mol-1 
D)  +110.7 kJ mol-1 
E)  -954.7 kJ mol-1 
A)  -3.2977 × 103 kJ mol-1 
B)  -312.9 kJ mol-1 
C)  +2.845 × 103 kJ mol-1 
D)  +110.7 kJ mol-1 
E)  -954.7 kJ mol-1

Question 7

Which of the following is TRUE if ln K is positive?

Accepted Answer

A)  ΔrG° is positive and the reaction is spontaneous in the forward direction. 
B)  ΔrG° is negative and the reaction is spontaneous in the forward direction. 
C)  ΔrG° is negative and the reaction is spontaneous in the reverse direction. 
D)  ΔrG° is positive and the reaction is spontaneous in the reverse direction. 
E)  ΔrG° is zero and the reaction is at equilibrium. 
A)  ΔrG° is positive and the reaction is spontaneous in the forward direction. 
B)  ΔrG° is negative and the reaction is spontaneous in the forward direction. 
C)  ΔrG° is negative and the reaction is spontaneous in the reverse direction. 
D)  ΔrG° is positive and the reaction is spontaneous in the reverse direction. 
E)  ΔrG° is zero and the reaction is at equilibrium.

Question 8

Place the following in order of increasing molar entropy at 298 K. NO CO SO

Accepted Answer

A)  NO < CO < SO 
B)  SO < CO < NO 
C)  SO < NO < CO 
D)  CO < SO < NO 
E)  CO < NO < SO 
A)  NO < CO < SO 
B)  SO < CO < NO 
C)  SO < NO < CO 
D)  CO < SO < NO 
E)  CO < NO < SO

Question 9

Determine the Q of a reaction at 298 K if ΔrG = -1.4 kJ mol-1 and ΔrG° = +4.3 kJ mol-1.

Accepted Answer

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

Question 10

Use Hess's law to calculate ΔrG° using the following information: NO(g) + O(g) → NO2(g) ΔrG° = ?
2O3(g) → 3O2(g) ΔrG° = +489.6 kJ mol-1
O2(g) → 2O(g) ΔrG° = +463.4 kJ mol-1
NO(g) + O3(g) → NO2(g) + O2(g) ΔrG° = - 199.5 kJ mol-1

Accepted Answer

A)  +753.5 kJ mol-1 
B)  +277.0 kJ mol-1 
C)  -676.0 kJ mol-1 
D)  -1152.5 kJ mol-1 
E)  -225.7 kJ mol-1 
A)  +753.5 kJ mol-1 
B)  +277.0 kJ mol-1 
C)  -676.0 kJ mol-1 
D)  -1152.5 kJ mol-1 
E)  -225.7 kJ mol-1

Question 11

Place the following in order of decreasing molar entropy at 298 K. HCl N2H4 Ar

Accepted Answer

A)  Ar > N2H4 > HCl 
B)  Ar > HCl > N2H4 
C)  N2H4 > Ar > HCl 
D)  N2H4 > HCl > Ar 
E)  HCl > N2H4 > Ar 
A)  Ar > N2H4 > HCl 
B)  Ar > HCl > N2H4 
C)  N2H4 > Ar > HCl 
D)  N2H4 > HCl > Ar 
E)  HCl > N2H4 > Ar

Question 12

Match the following.
-Q > 1

Accepted Answer

A) standard state 
B) equilibrium 
C) ΔrG > ΔrG° 
D) ΔrG > 0 
E) DrG rG rG° 
A) standard state 
B) equilibrium 
C) ΔrG > ΔrG° 
D) ΔrG > 0 
E) DrG rG rG°

Question 13

Calculate ΔrG for the evaporation of methanol at 25°C under nonstandard conditions when   = 100.0 mbar CH3OH(l) → CH3OH(g)

Accepted Answer

A)  -1.4 kJ mol-1 
B)  +11 kJ mol-1 
C)  -5.7 kJ mol-1 
D)  +4.3 kJ mol-1 
E)  -4.8 kJ mol-1 
A)  -1.4 kJ mol-1 
B)  +11 kJ mol-1 
C)  -5.7 kJ mol-1 
D)  +4.3 kJ mol-1 
E)  -4.8 kJ mol-1

Question 14

Determine the Q of a reaction at 298 K if ΔrG = +2.2 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 
A)  0.10 
B)  0.0010 
C)  0.00010 
D)  0.34 
E)  0.89

Question 15

Identify the compound with the highest standard Gibbs energy of formation.

Accepted Answer

A)  NaCl(s) 
B)  N2(g) 
C)  NO(g) 
D)  O3(g) 
E)  Cl2(g) 
A)  NaCl(s) 
B)  N2(g) 
C)  NO(g) 
D)  O3(g) 
E)  Cl2(g)

Question 16

Which of the following processes have a ΔrS > 0?

Accepted Answer

A)  CH3OH(l) → CH3OH(s) 
B)  N2(g) + 3H2(g) → 2NH3(g) 
C)  CH4(g) + H2O (g) → CO(g) + 3H2(g) 
D)  Na2CO3(s) + H2O(g) + CO2(g) → 2NaHCO3(s) 
E)  H2O(g) → H2O(l) 
A)  CH3OH(l) → CH3OH(s) 
B)  N2(g) + 3H2(g) → 2NH3(g) 
C)  CH4(g) + H2O (g) → CO(g) + 3H2(g) 
D)  Na2CO3(s) + H2O(g) + CO2(g) → 2NaHCO3(s) 
E)  H2O(g) → H2O(l)

Question 17

The value of ΔfG° at 400.0 °C for the formation of calcium chloride from its constituent elements, Ca(s) +   (g) →   (s)
Is ________ kJ mol-1. At 25.0 °C for this reaction, ΔfH° is -795.8 kJ mol-1, ΔfG° is -748.1 kJ mol-1, and   is

Accepted Answer

A)  -731.9 
B)  -903.3 
C)  1.07 × 105 
D)  6.31 × 104 
E)  -688.3 
A)  -731.9 
B)  -903.3 
C)  1.07 × 105 
D)  6.31 × 104 
E)  -688.3

Question 18

Why is heating your home with gas more efficient than heating it with electricity?

Accepted Answer

Heating with gas only requires a one-ste

Question 19

Calculate ΔrG° at 298 K using the following information: 2HNO3(aq) + NO(g) → 3NO2(g) + H2O(l) ΔrG° = ?
ΔfH° (kJ mol-1) -207.0 91.3 33.2 -285.8
S°(J K-1 mol-1) 146.0 210.8 240.1 70.0

Accepted Answer

A)  -151 kJ mol-1 
B)  -85.5 kJ mol-1 
C)  +50.8 kJ mol-1 
D)  +222 kJ mol-1 
E)  -186 kJ mol-1 
A)  -151 kJ mol-1 
B)  -85.5 kJ mol-1 
C)  +50.8 kJ mol-1 
D)  +222 kJ mol-1 
E)  -186 kJ mol-1

Question 20

Define the third law of thermodynamics.

Accepted Answer

The entropy of a per

Exam 17: Gibbs Energy and Thermodynamics

Above what temperature does the following reaction become nonspontaneous? FeO(s) + CO(g) → CO2(g) + Fe(s) ΔrH = -11.0 kJ; ΔrS = -17.4 J K-1 mol-1

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

For the following example, what is true about ΔrH and ΔrS? 3O2(g) → 2O3(g)

Calculate ΔrG° at 298 K using the following information: 4HNO3(g) + 5N2H4(l) → 7N2(g) + 12H2O(l) ΔrG° = ? ΔfH° (kJ mol-1) -133.9 50.6 -285.8 S°(J K-1 mol-1) 266.9 121.2 191.6 70.0

Which of the following statements is TRUE?

Calculate ΔrG° at 298 K using the following information: 4HNO3(g) + 5N2H4(l) → 7N2(g) + 12H2O(l) ΔrG° = ? ΔfG° (kJ mol-1) -73.5 149.3 -237.1

Which of the following is TRUE if ln K is positive?

Place the following in order of increasing molar entropy at 298 K. NO CO SO

Determine the Q of a reaction at 298 K if ΔrG = -1.4 kJ mol-1 and ΔrG° = +4.3 kJ mol-1.

Use Hess's law to calculate ΔrG° using the following information: NO(g) + O(g) → NO2(g) ΔrG° = ? 2O3(g) → 3O2(g) ΔrG° = +489.6 kJ mol-1 O2(g) → 2O(g) ΔrG° = +463.4 kJ mol-1 NO(g) + O3(g) → NO2(g) + O2(g) ΔrG° = - 199.5 kJ mol-1

Place the following in order of decreasing molar entropy at 298 K. HCl N2H4 Ar

Match the following. -Q > 1

Calculate ΔrG for the evaporation of methanol at 25°C under nonstandard conditions when = 100.0 mbar CH3OH(l) → CH3OH(g)

Determine the Q of a reaction at 298 K if ΔrG = +2.2 kJ mol-1 and ΔrG° = +19.3 kJ mol-1.

Identify the compound with the highest standard Gibbs energy of formation.

Which of the following processes have a ΔrS > 0?

The value of ΔfG° at 400.0 °C for the formation of calcium chloride from its constituent elements, Ca(s) + (g) → (s) Is ________ kJ mol-1. At 25.0 °C for this reaction, ΔfH° is -795.8 kJ mol-1, ΔfG° is -748.1 kJ mol-1, and is

Why is heating your home with gas more efficient than heating it with electricity?

Calculate ΔrG° at 298 K using the following information: 2HNO3(aq) + NO(g) → 3NO2(g) + H2O(l) ΔrG° = ? ΔfH° (kJ mol-1) -207.0 91.3 33.2 -285.8 S°(J K-1 mol-1) 146.0 210.8 240.1 70.0

Define the third law of thermodynamics.

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Above what temperature does the following reaction become nonspontaneous? FeO(s) + CO(g) → CO₂(g) + Fe(s) Δ_rH = -11.0 kJ; Δ_rS = -17.4 J K^-1 mol^-1

For the following example, what is true about Δ_rH and Δ_rS? 3O₂(g) → 2O₃(g)

Calculate Δ_rG° at 298 K using the following information: 4HNO₃(g) + 5N₂H₄(l) → 7N₂(g) + 12H₂O(l) Δ_rG°= ? Δ_fH° (kJ mol^-1) -133.9 50.6 -285.8 S°(J K^-1 mol^-1) 266.9 121.2 191.6 70.0

Calculate Δ_rG° at 298 K using the following information: 4HNO₃(g) + 5N₂H₄(l) → 7N₂(g) + 12H₂O(l) Δ_rG°= ? Δ_fG° (kJ mol^-1) -73.5 149.3 -237.1

Determine the Q of a reaction at 298 K if Δ_rG = -1.4 kJ mol^-1 and Δ_rG° = +4.3 kJ mol^-1.

Use Hess's law to calculate Δ_rG° using the following information: NO(g) + O(g) → NO₂(g) Δ_rG°= ? 2O₃(g) → 3O₂(g) Δ_rG°= +489.6 kJ mol^-1 O₂(g) → 2O(g) Δ_rG°= +463.4 kJ mol^-1 NO(g) + O₃(g) → NO₂(g) + O₂(g) Δ_rG°= - 199.5 kJ mol^-1

Place the following in order of decreasing molar entropy at 298 K. HCl N₂H₄ Ar

Calculate Δ_rG for the evaporation of methanol at 25°C under nonstandard conditions when = 100.0 mbar CH₃OH(l) → CH₃OH(g)

Determine the Q of a reaction at 298 K if Δ_rG = +2.2 kJ mol^-1 and Δ_rG° = +19.3 kJ mol^-1.

Which of the following processes have a Δ_rS > 0?

The value of Δ_fG° at 400.0 °C for the formation of calcium chloride from its constituent elements, Ca(s) + (g) → (s) Is ________ kJ mol^-1. At 25.0 °C for this reaction, Δ_fH° is -795.8 kJ mol^-1, Δ_fG° is -748.1 kJ mol^-1, and is

Calculate Δ_rG° at 298 K using the following information: 2HNO₃(aq) + NO(g) → 3NO₂(g) + H₂O(l) Δ_rG°= ? Δ_fH°(kJ mol^-1) -207.0 91.3 33.2 -285.8 S°(J K^-1 mol^-1) 146.0 210.8 240.1 70.0