Deck 18: Free Energy and Thermodynamics

Question 1

Identify the process that is spontaneous.

A) rusting of iron
B) electrolysis
C) browning of bread
D) photosynthesis
E) frying an egg

Answer 1

rusting of iron

Question 2

Consider a reaction that has a positive ΔH and a positive ΔS.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) It is not possible to determine without more information.

Answer 2

This reaction will be nonspontaneous only at low temperatures.

Question 3

Consider a reaction that has a negative ΔH and a negative ΔS.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) It is not possible to determine without more information.

Answer 3

This reaction will be spontaneous only at low temperatures.

Question 4

The ________ Law of Thermodynamics states that for any spontaneous reaction,the entropy of the universe increases.

A) Zero
B) First
C) Second
D) Third
E) Fourth

Question 5

Consider a reaction that has a positive ΔH and a negative ΔS.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) It is not possible to determine without more information.

Question 6

A spontaneous reaction occurs

A) with expansion of the volume.
B) with the application of cold.
C) with the application of heat.
D) without ongoing outside intervention.
E) with a catalyst.

Question 7

What is the sign of Δuniv for a living biological system?

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

Question 8

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

A) 6.762 × 10³ K
B) 158.7 K
C) 298 K
D) This reaction is nonspontaneous at all temperatures.
E) This reaction is spontaneous at all temperatures.

Question 9

Identify a process that is NOT reversible.

A) melting of steel
B) freezing water
C) melting of ice
D) frying an egg
E) deposition of carbon dioxide

Question 10

The ________ Law of Thermodynamics states the energy is conserved in chemical processes.

A) Zero
B) First
C) Second
D) Third
E) Fourth

Question 11

Which of the following statements is 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 is true.

Question 12

An exothermic reaction is a process that

A) has a negative ΔH_sys and a positive ΔS_surr.
B) has a negative ΔH_sys and a negative ΔS_surr.
C) has a positive ΔH_sys and a positive ΔS_surr.
D) has a positive ΔH_sys and a negative ΔS_surr.

Question 13

Identify the process that is endothermic.

A) vaporization
B) deposition
C) freezing
D) condensation

Question 14

An endothermic reaction is a process that

A) has a negative ΔH_sys and a positive ΔS_surr.
B) has a negative ΔH_sys and a negative ΔS_surr.
C) has a positive ΔH_sys and a positive ΔS_surr.
D) has a positive ΔH_sys and a negative ΔS_surr.

Question 15

Consider a reaction that has a negative ΔH and a negative ΔS.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) It is not possible to determine without more information.

Question 16

Consider a reaction that has a positive ΔH and a positive ΔS.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) It is not possible to determine without more information.

Question 17

Consider a reaction that has a negative ΔH and a positive ΔS.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) It is not possible to determine without more information.

Question 18

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

A) ΔG is proportional to -ΔS_univ
B) ΔG > 0 represents a spontaneous process
C) ΔG > 0 represents an increase in kinetic energy
D) ΔG < 0 represents a nonspontaneous process
E) All of the above are correct

Question 19

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) None of the above is true.

Question 20

Identify the process in which the entropy increases.

A) a decrease in the number of moles of a gas during a chemical reaction
B) the phase transition from a gas to a liquid
C) the phase transition from a solid to a gas
D) the phase transition from a gas to a solid
E) the phase transition from a liquid to a solid

Question 21

Place the following in order of increasing 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 22

Given the following equation, N₂O(g)+ NO₂(g)→ 3 NO(g)ΔG°_rxn = -23.0 kJ
Calculate ΔG°_rxn for the following reaction.
3 NO(g)→ N₂O(g)+ NO₂(g)

A) -23.0 kJ
B) 69.0 kJ
C) -69.0 kJ
D) -7.67 kJ
E) 23.0 kJ

Question 23

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

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

Question 24

Give the name of the reaction that achieves the theoretical limits with respect to free energy in thermodynamics.

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

Question 25

Identify the element with the highest standard free energy of formation.

A) Ba(s)
B) Ca(s)
C) Li(s)
D) K(s)
E) All elements have a value of zero.

Question 26

Identify the compound with the highest ΔG°_f.

A) N₂(g)
B) H₂(g)
C) O₂(g)
D) Cl₂(g)
E) All compounds have a value of zero.

Question 27

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 28

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

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

Question 29

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 30

Below what temperature does the following reaction become nonspontaneous? 2 HNO₃(aq)+ NO(g)→ 3 NO₂(g)+ H₂O(l)ΔH = +136.5 kJ; ΔS = +287.5 J/K

A) 39.2 K
B) 151 K
C) 475 K
D) This reaction is nonspontaneous at all temperatures.
E) This reaction is spontaneous at all temperatures.

Question 31

The ________ Law of Thermodynamics states the entropy of a perfect crystal at absolute zero is zero.

A) Zero
B) First
C) Second
D) Third
E) Fourth

Question 32

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

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

Question 33

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

A) NaCl(s)
B) NaBr(s)
C) NaI(s)
D) NaF(s)
E) They have the same value.

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

Identify the statement that is FALSE.

A) The entropy of a gas is greater than the entropy of a liquid.
B) Entropy generally increases with increasing molecular complexity.
C) Free atoms have greater entropy than molecules.
D) Entropy increases with dissolution.
E) For noble gasses, entropy increases with size.

Question 36

Give the name of the reaction that does not achieve the theoretical limits with respect to free energy in thermodynamics.

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

Question 37

What can change the direction of a reversible reaction involving gases?

A) change in temperature
B) change in pressure
C) change in volume
D) all of the above
E) none of the above

Question 38

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

A) 632 K
B) 298 K
C) 191 K
D) This reaction is nonspontaneous at all temperatures.
E) This reaction is spontaneous at all temperatures.

Question 39

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_universe is always greater than zero for a nonspontaneous process.
E) None of the above is true.

Question 40

For a given compound,list the decreasing order of entropy for a liquid,solid,and gas.

A) solid > gas > liquid
B) liquid > solid > gas
C) gas > liquid > solid
D) gas > solid > liquid
E) solid > liquid > gas

Question 41

Calculate ΔG_rxn at 298 K under the conditions shown below for the following reaction. CaCO₃(s)→ CaO(s)+ CO₂(g)ΔG° = +131.1 kJ
P(CO₂)= 0.033 atm

A) -49.3 kJ
B) -8.32 kJ
C) +122.6 kJ
D) +39.7 kJ
E) +43.3 kJ

Question 42

Identify the process which is exothermic and spontaneous.

A) melting of ice at 25°C
B) melting of ice to water
C) dissolution of sodium chloride in water
D) All of them are exothermic and spontaneous.
E) None of them is exothermic and spontaneous.

Question 43

Determine the equilibrium constant for the following reaction at 655 K. HCN(g)+ 2 H₂(g)→ CH₃NH₂(g)ΔH° = -158 kJ; ΔS°= -219.9 J/K

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

Question 44

Calculate ΔG_rxn at 298 K under the conditions shown below for the following reaction. 2 Hg(g)+ O₂(g)→ 2 HgO(s)ΔG° = -180.8 kJ
P(Hg)= 0.025 atm,P(O₂)= 0.037 atm

A) +207 kJ
B) -154.4 kJ
C) -26.5 kJ
D) -164 kJ
E) +60.7 kJ

Question 45

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

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

Question 46

Choose the statement below that is TRUE.

A) K > 1, ΔG°_rxn is positive.
B) K < 1, ΔG°_rxn is negative.
C) ΔG°_rxn = 0 at equilibrium.
D) ΔG_rxn = 0 at equilibrium.
E) None of the above statements are true.

Question 47

Use the free energies of formation given below to calculate the equilibrium constant (K)for the following reaction at 298 K. 2 HNO₃(aq)+ NO(g)→ 3 NO₂(g)+ H₂O(l)K = ?
ΔG°_f (kJ/mol)-110.9 87.6 51.3 -237.1

A) 8.71 × 10⁸
B) 0.980
C) 1.15 × 10^-9
D) 1.02
E) 5.11 × 10^-4

Question 48

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

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

Question 49

________ is a thermodynamic function that increases with the number of energetically equivalent ways to arrange components of a system to achieve a particular state.

A) Heat of fusion
B) Free energy
C) Entropy
D) Enthalpy
E) Molar nonequivalence

Question 50

Determine the equilibrium constant for the following reaction at 549 K. CH₂O(g)+ 2 H₂(g)→ CH₄(g)+ H₂O(g)ΔH° = -94.9 kJ; ΔS°= -224.2 J/K

A) 481
B) 1.07 × 10⁹
C) 2.08 × 10^-3
D) 9.35 × 10^-10
E) 1.94 × 10^-12

Question 51

What is true if ln K is 1?

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

Question 52

Calculate the ΔG°_rxn using the following information. 2 H₂S(g)+ 3 O₂(g)→ 2 SO₂(g)+ 2 H₂O(g)ΔG°_rxn = ?
ΔH°_f (kJ/mol)-20.6 -296.8 -241.8
S°(J/mol∙K)205.8 205.2 248.2 188.8

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

Question 53

Which of the following reactions will have the largest equilibrium constant (K)at 298 K?

A) CaCO₃(s) → CaO(s) + CO₂(g) ΔG° =+131.1 kJ
B) 2 Hg(g) + O₂(g) → 2 HgO(s) ΔG° = -180.8 kJ
C) 3 O₂(g) → 2 O₃(g) ΔG° = +326 kJ
D) Fe₂O₃(s) + 3 CO(g) → 2 Fe(s) + 3 CO₂(g) ΔG° = -28.0 kJ
E) It is not possible to determine without more information.

Question 54

What is true if ln K is negative?

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

Question 55

Determine the equilibrium constant for the following reaction at 498 K. 2 Hg(g)+ O₂(g)→ 2 HgO(s)ΔH° = -304.2 kJ; ΔS° = -414.2 J/K

A) 1.87 × 10¹⁰
B) 8.10 × 10³¹
C) 2.31 × 10^-22
D) 5.34 × 10^-11
E) 4.33 × 10²¹

Question 56

What is true if ln K is positive?

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

Question 57

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

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

Question 58

Determine the equilibrium constant for the following reaction at 298 K. Cl(g)+ O₃(g)→ ClO(g)+ O₂(g)ΔG° = - 34.5 kJ

A) 5.66 × 10⁵
B) 0.986
C) 8.96 × 10^-7
D) 4.98 × 10^-4
E) 1.12 × 10⁶

Question 59

Calculate ΔG_rxn at 298 K under the conditions shown below for the following reaction. 3 O₂(g)→ 2 O₃(g)ΔG° = +326 kJ
P(O₂)= 0.41 atm,P(O₃)= 5.2 atm

A) +341 kJ
B) +17.8 kJ
C) +332 kJ
D) -47.4 kJ
E) -109 kJ

Question 60

Which of the following is NOT true for ΔG_rxn?

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

Question 61

Which of the following processes has a ΔS < 0?

A) ethanol freezes
B) isopropyl alcohol condenses
C) 2-propanol (g, at 555 K) → 2-propanol (g, at 400 K)
D) carbon dioxide(g) → carbon dioxide(s)
E) All of the above processes have a ΔS < 0.

Question 62

Consider the following reaction at constant P.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)+ 2 O₂(g)→ 2 NO₂(g)ΔH = +66.4 kJ

A) ΔS_surr = +223 J/K, reaction is spontaneous
B) ΔS_surr = -223 J/K, reaction is not spontaneous
C) ΔS_surr = -66.4 J/K, reaction is not spontaneous
D) ΔS_surr = +2656 kJ/K, reaction is not spontaneous
E) ΔS_surr = -66.4 J/K, it is not possible to predict the spontaneity of this reaction without more information.

Question 63

For the following example,identify the following. I₂(l)→ I₂(g)

A) a negative ΔH and a negative ΔS
B) a positive ΔH and a negative ΔS
C) a negative ΔH and a positive ΔS
D) a positive ΔH and a positive ΔS
E) It is not possible to determine without more information.

Question 64

Which of the following processes has a ΔS > 0?

A) 2 NH₃(g) + CO₂(g) → NH₂CONH₂(aq) + H₂O(l)
B) lithium fluoride forms from its elements
C) 2 HCl(g) → H₂(g) + Cl₂(l)
D) cesium chloride dissolves in pure water
E) All of the above processes have a ΔS > 0.

Question 65

For the following example,identify the following. 2 F₂(g)+ O₂(g)→ 2 F₂O(g)

A) at low temperature, the reaction is spontaneous and ΔG < 0 and at high temperature, the reaction is spontaneous and ΔG < 0
B) at low temperature, the reaction is nonspontaneous and ΔG > 0 and at high temperature, the reaction is spontaneous and ΔG < 0
C) at low temperature, the reaction is spontaneous and ΔG < 0 and at high temperature, the reaction is nonspontaneous and ΔG > 0
D) at low temperature, the reaction is nonspontaneous and ΔG > 0 and at high temperature, the reaction is nonspontaneous and ΔG > 0
E) It is not possible to determine without more information.

Question 66

Place the following in order of decreasing standard molar entropy. NaI(s)K₃PO₄(aq)NaI(aq)

A) NaI(s) > NaI(aq) > K₃PO₄(aq)
B) NaI(aq) > NaI(s) > K₃PO₄(aq)
C) K₃PO₄(aq) > NaI(aq) > NaI(s)
D) NaI(s) > K₃PO₄(aq) > NaI(aq)
E) NaI(aq) > K₃PO₄(aq) > NaI(s)

Question 67

For the following example,identify the following. 2 N₂O(g)→ 2 N₂(g)+ O₂(g)

A) a negative ΔH and a negative ΔS
B) a positive ΔH and a negative ΔS
C) a negative ΔH and a positive ΔS
D) a positive ΔH and a positive ΔS
E) It is not possible to determine without more information.

Question 68

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

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

Question 69

Which of the following processes has a ΔS > 0?

A) SO₂ (l) → SO₂ (s)
B) N₂(g) + 3 H₂(g) → 2 NH₃(g)
C) CH₄(g) + H₂O(g) → CO(g) + 3 H₂(g)
D) K₂CO₃(s) + H₂O(g) + CO₂(g) → 2 KHCO₃(s)
E) All of the above processes have a ΔS > 0.

Question 70

For the following example,identify the following. 2 F₂O(g)→ 2 F₂(g)+ O₂(g)

A) at low temperature, the reaction is spontaneous and ΔG < 0 and at high temperature, the reaction is spontaneous and ΔG < 0
B) at low temperature, the reaction is nonspontaneous and ΔG > 0 and at high temperature, the reaction is spontaneous and ΔG < 0
C) at low temperature, the reaction is spontaneous and ΔG < 0 and at high temperature, the reaction is nonspontaneous and ΔG > 0
D) at low temperature, the reaction is nonspontaneous and ΔG > 0 and at high temperature, the reaction is nonspontaneous and ΔG > 0
E) It is not possible to determine without more information.

Question 71

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

Question 72

For the following example,identify the following. 2 H₂(g)+ O₂(g)→ 2 H₂O(g)

A) a negative ΔH and a negative ΔS
B) a positive ΔH and a negative ΔS
C) a negative ΔH and a positive ΔS
D) a positive ΔH and a positive ΔS
E) It is not possible to determine without more information.

Question 73

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

A) ΔS_surr = -114 kJ/K, reaction is spontaneous
B) ΔS_surr = +114 kJ/K, reaction is spontaneous
C) ΔS_surr = +321 J/K, reaction is spontaneous
D) ΔS_surr = -321 J/K, reaction is not spontaneous
E) ΔS_surr = +114 J/K, it is not possible to predict the spontaneity of this reaction without more information.

Question 74

For the following example,identify the following. F₂(l)→ F₂(s)

A) a negative ΔH and a negative ΔS
B) a positive ΔH and a negative ΔS
C) a negative ΔH and a positive ΔS
D) a positive ΔH and a positive ΔS
E) It is not possible to determine without more information.

Question 75

Which one of the following has the highest standard molar entropy,S°,at 45°C?

A) I₂(g)
B) H₂(g)
C) Br₂(l)
D) N₂(g)
E) Cl₂(g)

Question 76

For the following example,identify the following. F₂(l)→ F₂(s)

A) at low temperature, the reaction is spontaneous and ΔG < 0 and at high temperature, the reaction is spontaneous and ΔG < 0
B) at low temperature, the reaction is nonspontaneous and ΔG > 0 and at high temperature, the reaction is spontaneous and ΔG < 0
C) at low temperature, the reaction is spontaneous and ΔG < 0 and at high temperature, the reaction is nonspontaneous and ΔG > 0
D) at low temperature, the reaction is nonspontaneous and ΔG > 0 and at high temperature, the reaction is nonspontaneous and ΔG > 0
E) It is not possible to determine without more information.

Question 77

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

A) 2 NO(g) + O₂(g) → 2 NO₂(g)
B) COBr₂(g) → CO(g) + Br₂(g)
C) CH₃OH(l) → CO(g) + 2 H₂(g)
D) LiBrO₃(s) → Li⁺(aq) + BrO₃^-(aq)
E) None of the above will show a decrease in entropy.

Question 78

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

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

Question 79

For the following example,identify the following. F₂(l)→ F₂(g)

A) at low temperature, the reaction is spontaneous and ΔG < 0 and at high temperature, the reaction is spontaneous and ΔG < 0
B) at low temperature, the reaction is nonspontaneous and ΔG > 0 and at high temperature, the reaction is spontaneous and ΔG < 0
C) at low temperature, the reaction is spontaneous and ΔG < 0 and at high temperature, the reaction is nonspontaneous and ΔG > 0
D) at low temperature, the reaction is nonspontaneous and ΔG > 0 and at high temperature, the reaction is nonspontaneous and ΔG > 0
E) It is not possible to determine without more information.

Question 80

Place the following in order of increasing molar entropy at 298 K. CO C₅H₁₂ H₂

A) CO < C₅H₁₂ < H₂
B) C₅H₁₂ < CO < H₂
C) H₂ < CO < C₅H₁₂
D) C₅H₁₂ < H₂ < CO
E) CO < H₂ < C₅H₁₂