Deck 17: Gibbs Energy and Thermodynamics

Question 1

Identify the change in state that does not have an increase in entropy.

A) water freezing
B) water boiling
C) ice melting
D) dry ice subliming
E) water evaporating

Answer 1

water freezing

Question 2

Which of the following processes have a Δ_rS > 0?

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)

Answer 2

CH₄(g) + H₂O (g) → CO(g) + 3H₂(g)

Question 3

Consider a reaction that has a negative Δ_rH and a negative Δ_rS. Which of the following statements is TRUE?

A) This reaction will be spontaneous only at low temperatures.
B) This reaction will be spontaneous at all temperatures.
C) This reaction will be nonspontaneous at all temperatures.
D) This reaction will be nonspontaneous only at low temperatures.
E) This reaction will be spontaneous only at absolute zero (0 Kelvin).

Answer 3

This reaction will be spontaneous only at low temperatures.

Question 4

In which of the following processes do the molecules become more ordered?

A) water freezing
B) ice melting
C) water evaporating
D) salt dissolving in water
E) dry ice subliming

Question 5

For the following example, what is true about Δ_rH and Δ_rS? 2N₂O(g) → 2N₂(g) + O₂(g)

A) a negative Δ_rH and a negative Δ_rS
B) a positive Δ_rH and a negative Δ_rS
C) a negative Δ_rH and a positive Δ_rS
D) a positive Δ_rH and a positive Δ_rS
E) Δ_rH = 0 and a positive Δ_rS

Question 6

Which of the following processes have a Δ_rS > 0?

A) 2NH₃(g) + CO₂(g) → NH₂CONH₂(aq) + H₂O(l)
B) lithium fluoride forms from Li and F₂
C) 2HBr(g) → H₂(g) + Br₂(l)
D) sodium chloride dissolves in pure water
E) Ag⁺(aq) + Cl^-(aq) → AgCl(s)

Question 7

Consider a reaction that has a positive Δ_rH and a negative Δ_rS. Which of the following statements is TRUE?

A) This reaction will be spontaneous only at high temperatures.
B) This reaction will be spontaneous at all temperatures.
C) This reaction will be nonspontaneous at all temperatures.
D) This reaction will be nonspontaneous only at high temperatures.
E) This reaction will be spontaneous only at absolute zero (0 Kelvin).

Question 8

Consider the following reaction at constant pressure. 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. 4NH₃(g) + 3O₂(g) → 2N₂(g) + 6H₂O(g) Δ_rH = -1267 kJ

A) ΔS_surr = +12.67 kJ K^-1 mol^-1, reaction is not spontaneous
B) ΔS_surr = -12.67 kJ K^-1 mol^-1, reaction is spontaneous
C) ΔS_surr = +50.4 kJ K^-1 mol^-1, reaction is not spontaneous
D) ΔS_surr = +3.18 kJ K^-1 mol^-1, reaction is spontaneous
E) ΔS_surr = -3.18 kJ K^-1 mol^-1, reaction is not spontaneous

Question 9

Which of the following statements is TRUE?

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 10

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

A) ΔS_surr = +223 J K^-1 mol^-1, reaction is spontaneous
B) ΔS_surr = -223J K^-1 mol^-1, reaction is not spontaneous
C) ΔS_surr = -66.4 J K^-1 mol^-1, reaction is spontaneous
D) ΔS_surr = +66.4 kJ K^-1 mol^-1, reaction is not spontaneous
E) ΔS_surr = -66.4 J K^-1 mol^-1, reaction is not spontaneous

Question 11

Which of the following relationships is correct at constant T and P?

A) Δ_rG is proportional to -ΔS_univ.
B) Δ_rG > 0 represents a spontaneous process.
C) Δ_rG > 0 represents an increase in kinetic energy.
D) Δ_rG < 0 represents a nonspontaneous process.
E) Δ_rG is not a function of temperature.

Question 12

Which of the following processes shows a decrease in entropy of the system?

A) 2NO(g) + O₂(g) → 2NO₂(g)
B) COCl₂(g) → CO(g) + Cl₂(g)
C) CH₃OH(l) → CO(g) + 2H₂(g)
D) NaClO₃(s) → Na⁺(aq) + ClO₃^-(aq)
E) H₂(g) + Cl₂(g) → 2HCl(g)

Question 13

Consider a reaction that has a negative Δ_rH and a negative Δ_rS. Which of the following statements is TRUE?

A) This reaction will be spontaneous only at high temperatures.
B) This reaction will be spontaneous at all temperatures.
C) This reaction will be nonspontaneous at all temperatures.
D) This reaction will be nonspontaneous only at high temperatures.
E) This reaction will be spontaneous only at absolute zero (0 Kelvin).

Question 14

Which of the following processes have a Δ_rS = 0?

A) water freezes
B) isopropyl alcohol vapour condenses
C) methanol (g, at 555 K) → methanol (g, at 400 K)
D) carbon dioxide(g) → carbon dioxide(s)
E) H₂(g) + F₂(g) → 2HF(g)

Question 15

Which of the following statements is TRUE?

A) A spontaneous reaction is a reaction that takes place without any outside intervention.
B) Thermodynamics is a study of reaction rates.
C) A nonspontaneous reaction is a reaction that does not take place under any conditions.
D) Chemical kinetics is a discipline that studies the spontaneity of chemical reactions.
E) Every spontaneous reaction is a very rapid reaction.

Question 16

Consider the following reaction at constant pressure. Use the information here to determine the value of ?S_surr at 355 K. Predict whether or not this reaction will be spontaneous at this temperature. 2NO(g) + O₂(g) ? 2NO₂(g) ?_rH = -114 kJ

A) ?S_surr = +114 kJ K^-1 mol^-1, reaction is spontaneous
B) ?S_surr = +114 kJ K^-1 mol^-1, reaction is not spontaneous
C) ?S_surr = +321 J K^-1 mol^-1, reaction is spontaneous
D) ?S_surr = -321 J K^-1 mol^-1, reaction is not spontaneous
E) ?S_surr = +321 J K^-1 mol^-1, reaction is not spontaneous

Question 17

What is the sign of ΔS_univ for a biological system?

A) positive
B) negative
C) zero
D) It depends on the biological system.

Question 18

Consider a reaction that has a positive Δ_rH and a positive Δ_rS. Which of the following statements is TRUE?

A) This reaction will be spontaneous only at low temperatures.
B) This reaction will be spontaneous at all temperatures.
C) This reaction will be nonspontaneous at all temperatures.
D) This reaction will be nonspontaneous at low temperatures.
E) This reaction will be spontaneous only at absolute zero (0 Kelvin).

Question 19

Consider a reaction that has a positive Δ_rH and a positive Δ_rS. Which of the following statements is TRUE?

A) This reaction will be spontaneous only at high temperatures.
B) This reaction will be spontaneous at all temperatures.
C) This reaction will be nonspontaneous at all temperatures.
D) This reaction will be nonspontaneous only at high temperatures.
E) This reaction will be spontaneous only at very low temperatures.

Question 20

Consider a reaction that has a negative Δ_rH and a positive Δ_rS. Which of the following statements is TRUE?

A) This reaction will be spontaneous only at high temperatures.
B) This reaction will be spontaneous at all temperatures.
C) This reaction will be nonspontaneous at all temperatures.
D) This reaction will be nonspontaneous only at high temperatures.
E) This reaction will be spontaneous only at absolute zero (0 Kelvin).

Question 21

Use the following thermodynamic values to calculate Δ_{r NEWLINE} .
Δ_r
= -95 kJ , Δ_r
= -157 J , T = 855 K

A) -48 kJ
B) -68 kJ
C) +39 kJ
D) -157 kJ
E) +142 kJ

Question 22

Identify the statement that is TRUE.

A) The entropy of a gas is lower than the entropy of a liquid.
B) Entropy generally decreases with increasing molecular complexity.
C) Free atoms have lower entropy than molecules.
D) Entropy decreases with dissolution.
E) For noble gases, entropy decreases with increase in atomic size.

Question 23

Place the following in order of increasing molar entropy at 298 K. CO₂ C₃H₈ SO

A) CO₂ < C₃H₈ < SO
B) C₃H₈ < CO₂ < SO
C) SO < CO₂ < C₃H₈
D) C₃H₈ < SO < CO₂
E) CO₂ < SO < C₃H₈

Question 24

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

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

Question 25

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

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

Question 26

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

A) a negative Δ_rH and a negative Δ_rS
B) a positive Δ_rH and a negative Δ_rS
C) a negative Δ_rH and a positive Δ_rS
D) a positive Δ_rH and a positive Δ_rS
E) Δ_rH = 0 and a positive Δ_rS

Question 27

Use the following thermodynamic values to calculate Δ_r .
Δ_r
= +95 kJ , Δ_r
= -157 J , T = 398 K

A) -48 kJ
B) -68 kJ
C) +39 kJ
D) +157 kJ
E) +142 kJ

Question 28

Which of the following statements is TRUE?

A) Entropy is an extensive property.
B) Entropy is not temperature dependent.
C) Exothermic processes decrease the entropy of the surroundings.
D) ΔS_univ is always greater than zero for a nonspontaneous process.
E) Just like enthalpy, entropy has no absolute zero value.

Question 29

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

A) a negative Δ_rH and a negative Δ_rS
B) a positive Δ_rH and a negative Δ_rS
C) a negative Δ_rH and a positive Δ_rS
D) a positive Δ_rH and a positive Δ_rS
E) Δ_rH = 0 and a positive Δ_rS

Question 30

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

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 31

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

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 32

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

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

Question 33

Below what temperature does the following reaction become nonspontaneous? 2HNO₃(aq) + NO(g) → 3NO₂(g) + H₂O(l) Δ_rH = +136.5 kJ; Δ_rS = +287.5 J K^-1 mol^-1

A) 39.2 K
B) 151 K
C) 475 K
D) 4.75 × 10³ K
E) 298.17 K

Question 34

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

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

Question 35

Place the following in order of decreasing molar entropy at 298 K. H₂ Cl₂ F₂

A) H₂ > Cl₂ > F₂
B) Cl₂ > H₂ > F₂
C) F₂ > Cl₂ > H₂
D) H₂ > F₂ > Cl₂
E) Cl₂ > F₂ > H₂

Question 36

Use the following thermodynamic values to calculate Δ_r .
Δ_r
= -95 kJ , Δ_r
= -157 J , T = 298 K

A) -48 kJ
B) -68 kJ
C) + 39 kJ
D) -157 kJ
E) +142 kJ

Question 37

Use the following thermodynamic values to calculate Δ_r .
Δ_r
= +95 kJ , Δ_r
= -157 J , T = 298 K

A) -48 kJ
B) -68 kJ
C) +39 kJ
D) -157 kJ
E) +142 kJ

Question 38

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

A) H₂O(g) < H₂O(l) < H₂O(s)
B) H₂O(s) < H₂O(l) < H₂O(g)
C) H₂O(g) < H₂O(s) < H₂O(l)
D) H₂O(l) < H₂O(s) < H₂O(g)
E) H₂O(s) < H₂O(g) < H₂O(l)

Question 39

Place the following in order of decreasing standard molar entropy. N₂O₄ NO NO₂

A) N₂O₄ > NO₂ > NO
B) NO > NO₂ > N₂O₄
C) N₂O₄ > NO > NO₂
D) NO > N₂O₄ > NO₂
E) NO₂ > NO > N₂O₄

Question 40

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

A) a negative Δ_rH and a negative Δ_rS
B) a positive Δ_rH and a negative Δ_rS
C) a negative Δ_rH and a positive Δ_rS
D) a positive Δ_rH and a positive Δ_rS
E) Δ_rH = 0 and a positive Δ_rS

Question 41

Given the following equation, N₂O(g) + NO₂(g) → 3NO(g) Δ_rG° = -23.0 kJ mol^-1
Calculate Δ_rG° for the following reaction:
3N₂O(g) + 3NO₂(g) → 9NO(g)

A) -23.0 kJ mol^-1
B) 69.0 kJ mol^-1
C) -69.0 kJ mol^-1
D) -7.67 kJ mol^-1
E) 23.0 kJ mol^-1

Question 42

What is the change in Gibbs energy of a process?

A) It is a maximum amount of energy available to do work.
B) It is energy that is lost to the surroundings.
C) It is energy that is used to break chemical bonds.
D) It is energy that is converted to heat.
E) It is the total energy of a process.

Question 43

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

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

Question 44

Given the following equation, N₂O(g) + NO₂(g) → 3NO(g) Δ_rG° = -23.0 kJ mol^-1
Calculate Δ_rG^o for the following reaction:
3NO(g) → N₂O(g) + NO₂(g)

A) -23.0 kJ mol^-1
B) 69.0 kJ mol^-1
C) -69.0 kJ mol^-1
D) -7.67 kJ mol^-1
E) 23.0 kJ mol^-1

Question 45

Calculate Δ_rS° for the following reaction. The S° for each species is shown below the reaction. 4NH₃(g) + 5O₂(g) → 4NO(g) + 6H₂O(g)
S°(J K^-1 mol^-1) 192.8 205.2 210.8 188.8

A) +287.4 J K^-1 mol^-1
B) -401.2 J K^-1 mol^-1
C) +160.0 J K^-1 mol^-1
D) -336.6 J K^-1 mol^-1
E) +178.8 J K^-1 mol^-1

Question 46

Identify the compound with the standard Gibbs energy of formation equal to zero.

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

Question 47

What is the name of the reaction that achieves the theoretical limits with respect to the change in Gibbs energy in thermodynamics?

A) reversible reaction
B) forward reaction
C) reverse reaction
D) equilibrium reaction
E) irreversible reaction

Question 48

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

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

Question 49

Calculate Δ_rS° for the following reaction. The S° for each species is shown below the reaction. C₂H₂(g) + 2H₂(g) → C₂H₆(g)
S°(J K^-1 mol^-1) 200.9 130.7 229.2

A) +303.3 J K^-1 mol^-1
B) +560.8 J K^-1 mol^-1
C) -102.4 J K^-1 mol^-1
D) -233.1 J K^-1 mol^-1
E) 229.2 J K^-1 mol^-1

Question 50

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

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 51

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

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 52

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

A) NaCl(s)
B) N₂(g)
C) NO(g)
D) O₃(g)
E) Cl_2(g)

Question 53

Which of the following is TRUE regarding allotropes?

A) Allotropes are different forms of the same element, but they have identical standard molar enthalpies.
B) Allotropes are different forms of the same element and have different standard molar enthalpies.
C) Allotropes are composed of different isotopes of the same element and have different standard molar enthalpies.
D) Allotropes are composed of different isotopes of the same element and identical standard molar enthalpies.
E) Allotropes are different elements with the same structure and have different standard molar enthalpies.

Question 54

Calculate ΔρS° for the following reaction. The S° for each species is shown below the reaction. P₄(g) + 10Cl₂(g) → 4PCl₅(g)
S°(J K^-1 mol^-1) 280.0 223.1 364.6

A) -138.5 J K^-1 mol^-1
B) -1052.6 J K^-1 mol^-1
C) +171.3 J K^-1 mol^-1
D) -583.6 J K^-1 mol^-1
E) +2334.6 J K^-1 mol^-1

Question 55

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

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

Question 56

What is the name of the reaction that does not achieve the theoretical limits with respect to the change in Gibbs energy in thermodynamics?

A) reversible reaction
B) forward reaction
C) reverse reaction
D) equilibrium reaction
E) irreversible reaction

Question 57

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

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

Question 58

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

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

Question 59

Given the following equation, N₂O(g) + NO₂(g) → 3 NO(g) Δ_rG° = -23.0 kJ mol^-1
Calculate Δ_rG° for the following reaction:
9NO(g) → 3N₂O(g) + 3NO₂(g)

A) -23.0 kJ mol^-1
B) 69.0 kJ mol^-1
C) -69.0 kJ mol^-1
D) -7.67 kJ mol^-1
E) 23.0 kJ mol^-1

Question 60

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

A) N₂O₄(g)
B) H₂(g)
C) N₂(g)
D) H₂O(g)
E) O₂(g)

Question 61

Calculate Δ_rG at 298 K under the conditions shown below for the following reaction: Fe₂O₃(s) + 3CO(g) → 2Fe(s) + 3CO₂(g) ΔG° = -28.0 kJ mol^-1
P(CO) = 1.4 atm, P(CO₂) = 2.1 atm

A) +31.0 kJ mol^-1
B) +2.99 kJ mol^-1
C) -30.7 kJ mol^-1
D) +17.5 kJ mol^-1
E) -25.0 kJ mol^-1

Question 62

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

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 63

Calculate Δ_rG° at 298 K using the following information: 2HNO₃(aq) + NO(g) → 3NO₂(g) + H₂O(l) Δ_rG° = ?
Δ_fG° (kJ mol^-1) -110.9 87.6 51.3 -237.1

A) -162.5 kJ mol^-1
B) +51.0 kJ mol^-1
C) -54.5 kJ mol^-1
D) +171.1 kJ mol^-1
E) -87.6 kJ mol^-1

Question 64

Calculate Δ_rG° at 298 K using the following information: 2H₂S(g) + 3O₂(g) → 2SO₂(g) + 2H₂O(g) Δ_rG° = ?
Δ_fG°(kJ mol^-1) -33.4 -300.1 -228.6

A) +112.4 kJ mol^-1
B) -495.3 kJ mol^-1
C) -528.7 kJ mol^-1
D) +66.8 kJ mol^-1
E) -990.6 kJ mol^-1

Question 65

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

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 66

Determine Δ_rG° at 298 K using the following information: H₂(g) + CO(g) → CH₂O(g) Δ_rH°= +1.9 kJ mol^-1; Δ_rS°= -109.6 J K^-1 mol^-1

A) +57.7 kJ mol^-1
B) -30.8 kJ mol^-1
C) +34.6 kJ mol^-1
D) -41.5 kJ mol^-1
E) +17.3 kJ mol^-1

Question 67

Use Hess's law to calculate Δ_rG° using the following information: ClO(g) + O₃(g) → Cl(g) + 2O₂(g) Δ_rG° = ?
2O₃(g)→ 3O₂(g) Δ_rG° = +489.6 kJ mol^-1
Cl(g) + O₃(g) → ClO(g) + O₂(g) Δ_rG° = -34.5 kJ mol^-1

A) -472.4 kJ mol^-1
B) -210.3 kJ mol^-1
C) +455.1 kJ mol^-1
D) +262.1 kJ mol^-1
E) +524.1 kJ mol^-1

Question 68

Estimate Δ_rG° for the following reaction at 775 K. 2Hg(g) + O₂(g) → 2HgO(s) Δ_rH°= -304.2 kJ mol^-1; Δ_rS°= -414.2 J K^-1 mol^-1

A) -625 kJ mol^-1
B) -181 kJ mol^-1
C) +17 kJ mol^-1
D) +321 kJ mol^-1
E) -110 kJ mol^-1

Question 69

Estimate Δ_rG° for the following reaction at 387 K. HCN(g) + 2H₂(g) → CH₃NH₂(g) Δ_rH°= -158.0 kJ mol^-1; Δ_rS°= -219.9 J K^-1 mol^-1

A) +243 kJ mol^-1
B) -72.9 kJ mol^-1
C) +84.9 kJ mol^-1
D) -92.5 kJ mol^-1
E) -188 kJ mol^-1

Question 70

Use Hess's law to calculate Δ_rG° using the following information: CO(g) → C(s) + 1/2 O₂(g) Δ_rG° = ?
CO₂(g) → C(s) + O₂(g) Δ_rG° = +394.4 kJ mol^-1
CO(g) + 1/2 O₂(g) → CO₂(g) Δ_rG° = -257.2 kJ mol^-1

A) -60.0 kJ mol^-1
B) +651.6 kJ mol^-1
C) -265.8 kJ mol^-1
D) +137.2 kJ mol^-1
E) +523.0 kJ mol^-1

Question 71

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

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 72

Calculate Δ_rG° at 298 K using the following information: 2H₂S(g) + 3O₂(g) → 2SO₂(g) + 2H₂O(g) Δ_rG° = ?
Δ_fH° (kJ mol^-1) -20.6 -296.8 -241.8
S°(J K^-1 mol^-1) 205.8 205.2 248.2 188.8

A) -990.3 kJ mol^-1
B) +108.2 kJ mol^-1
C) -466.1 kJ mol^-1
D) +676.2 kJ mol^-1
E) -147.1 kJ mol^-1

Question 73

Estimate Δ_rG° for the following reaction at 449.0 K. CH₂O(g) + 2H₂(g) → CH₄(g) + H₂O(g) Δ_rH°= -94.9 kJ mol^-1; Δ_rS°= -224.2 J K^-1 mol^-1

A) +5.8 kJ mol^-1
B) +12.9 kJ mol^-1
C) -101 kJ mol^-1
D) +2.4 kJ mol^-1
E) -4.2 kJ mol^-1

Question 74

Determine Δ_rG° at 298 K using the following information: CaCO₃(s) → CaO(s) + CO₂(g) Δ_rH°= +179.2 kJ mol^-1; Δ_rS°= +160.2 J K^-1 mol^-1

A) -607.0 kJ mol^-1
B) +112 .0 kJ mol^-1
C) -89.3 kJ mol^-1
D) +131.5 kJ mol^-1
E) +228.1 kJ mol^-1

Question 75

Determine Δ_rG° at 298 K using the following information: 2CH₄(g) → C₂H₆(g) + H₂(g) Δ_rH°= +64.6 kJ mol^-1; Δ_rS°= -12.7 J K^-1 mol^-1

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 76

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

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 77

Determine Δ_rG° at 298 K using the following information: FeO(s) + CO(g) → Fe(s) + CO₂(g) Δ_rH°= -11.0 kJ mol^-1; Δ_rS°= -17.4 J K^-1 mol^-1

A) +191.0 kJ mol^-1
B) -5.8 kJ mol^-1
C) +1.6 kJ mol^-1
D) -6.4 kJ mol^-1
E) +89.5 kJ mol^-1

Question 78

Determine Δ_rG° at 298 K using the following information: N₂(g) + O₂(g) → 2NO(g) Δ_rH°= +182.6 kJ mol^-1; Δ_rS°= +24.8 J K^-1 mol^-1

A) -607.0 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 79

Calculate Δ_rG at 298 K under the conditions shown below for the following reaction: SO₃(g) + H₂O(g) → H₂SO₄(l) Δ_rG°= -90.5 kJ mol^-1
P(SO₃) = 0.20 atm, P(H₂O) = 0.88 atm

A) +15.9 kJ mol^-1
B) -90.5 kJ mol^-1
C) +51.4 kJ mol^-1
D) -86.2 kJ mol^-1
E) -30.4 kJ mol^-1

Question 80

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

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