Question 1

Use the given thermodynamic data and the reaction below to calculate ?S°(universe)  for the formation of Fe2O3(s)  at 298.15 K. 3 Fe(s)  + 2 O2(g)  ? Fe3O4(s) 
  Species ΔfH∘(kJ/mol) S∘(J/K⋅mol) Fe(s) 0.027.8O2( g) 0.0205.1Fe3O4( s) −1118.4146.4\begin{array} { l l l } 	ext { Species } & \Delta _f H ^ { \circ } ( \mathrm { kJ } / \mathrm { mol } )  & S ^ { \circ } ( \mathrm { J } / \mathrm { K } \cdot \mathrm { mol } )  \\hline \mathrm { Fe } ( \mathrm { s } )  & 0.0 & 27.8 \\mathrm { O } _ { 2 } ( \mathrm {~g} )  & 0.0 & 205.1 \\mathrm { Fe } _ { 3 } \mathrm { O } _ { 4 } ( \mathrm {~s} )  & - 1118.4 & 146.4\end{array} Species Fe(s) O2​( g) Fe3​O4​( s) ​Δf​H∘(kJ/mol) 0.00.0−1118.4​S∘(J/K⋅mol) 27.8205.1146.4​​

Accepted Answer

A)   -3404 J/K
B)   -1162 J/K
C)   +561.2 J/K
D)   +3404 J/K
E)   +7639 J/K F) C) and D)
G) A) and B)

Question 2

For a certain reversible process, q = 88.06 kJ at 29.4°C. Which of the following is the ΔS for the process?

Accepted Answer

A)   0.291 J/K
B)   291 J/K
C)   3.00 J/K
D)   -0.291 J/K
E)   2590 J/KF) A) and E)
G) B) and C)

Question 3

Given the following data: 
S(g)  + O2(g)  → SO2(g) 
ΔrG° = -300.1 kJ/mol-rxn
2 S(g)  + 3 O2(g)  → 2 SO3(g) 
ΔrG° = -742.1 kJ/mol-rxn
Calculate ΔfG° for the reaction below.
SO2(g)  + 1/2 O2(g)  → SO3(g)

Accepted Answer

A)   -1042.2 kJ/mol-rxn
B)   -71.0 kJ/mol-rxn
C)   +2.47 kJ/mol-rxn
D)   +71.0 kJ/mol-rxn
E)   +1042.2 kJ/mol-rxnF) None of the above
G) A) and B)

Question 4

At what temperatures will a reaction be spontaneous if ΔrH° = +62.4 kJ and ΔrS° = +301 J/K?

Accepted Answer

A)   All temperatures below 207 K
B)   All temperatures above 207 K
C)   Temperatures between 179 K and 235 K
D)   The reaction will be spontaneous at any temperature
E)   The reaction will never be spontaneousF) A) and E)
G) B) and E)

Question 5

For which of the following substances is the standard free energy of formation not equal to zero at 298 K?

Accepted Answer

A)   Xe(g) 
B)   Sn(s) 
C)   N2(g) 
D)   Mg(g) 
E)   Mn(s) F) A) and B)
G) A) and C)

Question 6

_____ changes only occur in the direction that leads toward chemical equilibrium.

Accepted Answer

The answer of _____ changes only occur in the direction...

Question 7

What is the sign of ΔH (system)  and ΔS (system)  if a chemical reaction is spontaneous only at lower temperatures under standard conditions?

Accepted Answer

A)   ΔH (system)  is negative, and ΔS (system)  is negative.
B)   ΔH (system)  is positive, and ΔS (system)  is positive.
C)   ΔH (system)  is positive, and ΔS (system)  is negative.
D)   ΔH (system)  is negative, and ΔS (system)  is positive.
E)   None of theseF) A) and E)
G) D) and E)

Question 8

The total entropy of the universe is always increasing. This is a statement of the _____ law of thermodynamics.

Accepted Answer

The answer of The total entropy of the universe is...

Question 9

What is the equilibrium constant for reaction below at 25 °C? (R = 8.314 J/K?mol)  2 NO(g)  + O2(g)   ⇋\leftrightharpoons⇋  2 NO2(g) ; ?fG° [NO(g) ] = +86.6 kJ/mol and ?fG° [NO2(g) ] = +51.2 kJ/mol.

Accepted Answer

A)   3.9 × 10-13
B)   1.0 × 10-11
C)   2.6 × 1012
D)   1.6 × 106
E)   3.8 × 1028 F) D) and E)
G) A) and B)

Question 10

A flask containing helium gas is released into a closed room. Which of the following ideas concerning entropy is/are true?

Accepted Answer

A)   ΔS(system)  > 0
B)   Matter is dispersed.
C)   ΔS(universe)  > 0
D)   This process is spontaneous.
E)   All of these statements are true.F) A) and E)
G) A) and B)

Question 11

Which of the following relationships is not true?

Accepted Answer

A)    ΔGsys ∘=ΔHsys ∘−TΔSsys ∘\Delta G _ { 	ext {sys } } ^ { \circ } = \Delta H _ { 	ext {sys } } ^ { \circ } - T \Delta S _ { 	ext {sys } } ^ { \circ }ΔGsys ∘​=ΔHsys ∘​−TΔSsys ∘​ 
B)    ΔGsys ∘=−RTln⁡(K) \Delta G _ { 	ext {sys } } ^ { \circ } = - R T \ln ( K ) ΔGsys ∘​=−RTln(K)  
C)    ΔSuniv ∘=ΔSsys ∘+ΔSsurr ∘\Delta S _ { 	ext {univ } } ^ { \circ} = \Delta S _ { 	ext {sys } } ^ { \circ } + \Delta S _ { 	ext {surr } } ^ { \circ }ΔSuniv ∘​=ΔSsys ∘​+ΔSsurr ∘​ 
D)    ΔH=ΔHsys ∘+RTln⁡(K) \Delta H = \Delta H _ { 	ext {sys }}^{\circ} + R T \ln ( K ) ΔH=ΔHsys ∘​+RTln(K)  
E)    ΔGsys ∘=−TΔSuniv ∘\Delta G _ { 	ext {sys } } ^ { \circ } = - T \Delta S _ { 	ext {univ } } ^ { \circ }ΔGsys ∘​=−TΔSuniv ∘​F) B) and D)
G) B) and C)

Question 12

Which of the following linear chain alcohols is likely to have the highest standard entropy in the liquid state?

Accepted Answer

A)   CH3OH
B)   CH3CH2OH
C)   CH3CH2CH2OH
D)   CH3CH2CH2CH2OH
E)   CH3CH2CH2CH2CH2OHF) B) and D)
G) A) and D)

Question 13

If ΔrG° > 0 for a reaction at all temperatures, then ΔrH° is _____ and ΔrS° is _____.

Accepted Answer

A)   Negative; positive
B)   Positive; negative
C)   Negative; negative
D)   Positive; positive
E)   Positive; either positive or negativeF) None of the above
G) C) and D)

Question 14

For which of the following reactions will the entropy of a system decrease?

Accepted Answer

A)   2 NH3(g)  → N2(g)  + 3 H2(g) 
B)   2 C(s)  + O2(g)  → 2 CO(g) 
C)   CaCO3(s)  → CaO(s)  + CO2(g) 
D)   2 NO2(g)  → N2O4(g) 
E)   NaOH(s)  → Na+(aq)  + OH-(aq) F) A) and B)
G) A) and C)

Question 15

Which of the following is true of the deposition of a gaseous substance?

Accepted Answer

A)   ΔS° = 0 and ΔH° = 0.
B)   ΔS° > 0 and ΔH° > 0.
C)   ΔS°  0.
D)   ΔS° 
E)   ΔS° > 0 and ΔH° < 0.F) B) and E)
G) A) and C)

Question 16

A 100 mL sample of water is placed in a coffee cup calorimeter. When 1.0 g of an ionic solid is added, the temperature decreases from 21.5 °C to 20.8 °C as the solid dissolves. For the dissolving of the solid, _____.

Accepted Answer

A)   ΔH 
B)   ΔS(universe)  > 0
C)   ΔS(system)  
D)   ΔS(surroundings)  > 0
E)   None of theseF) A) and C)
G) B) and D)

Question 17

At a temperature (in kelvin units) of _____, the entropy of a pure crystal is 0.0 J/K.

Accepted Answer

The answer of At a temperature (in kelvin units) of...

Question 18

At what temperatures will a reaction be spontaneous if ΔrH° = +117 kJ and ΔrS° = -35 J/K?

Accepted Answer

A)   All temperatures below 94.1 K
B)   Temperatures between 12.7 K and 135 K
C)   All temperatures above 94.1 K
D)   The reaction will be spontaneous at any temperature.
E)   The reaction will never be spontaneous.F) C) and D)
G) C) and E)

Question 19

Which of the following compounds has the highest standard entropy per mole at 298 K?

Accepted Answer

A)   H2O(l) 
B)   CaCO3(s) 
C)   CO(g) 
D)   SiO2(s) 
E)   CH3OH(l) F) B) and E)
G) A) and E)

Question 20

Given the following and that R = 8.314 J/K ?mol, determine the equilibrium constant, K, at 298K for the following reaction: 
AgBr(s)  ? Ag+(aq)  + Br-(aq) 
  Substance Δ‾fG∘(kJ/mol)  at 298 KBr−(aq) −104.0Ag+(aq) 77.12AgBr(s) −96.9\begin{array}{ll}	ext { Substance } & \underline{\Delta}_{\mathrm{f}} \mathrm{G}^{\circ}(\mathrm{kJ} / \mathrm{mol})  	ext { at } 298 \mathrm{~K} \\hline\mathrm{Br}-(\mathrm{aq})  & -104.0 \\mathrm{Ag}^{+}(\mathrm{aq})  & 77.12 \\mathrm{AgBr}(\mathrm{s})  & -96.9\end{array} Substance Br−(aq) Ag+(aq) AgBr(s) ​Δ​f​G∘(kJ/mol)  at 298 K−104.077.12−96.9​​

Accepted Answer

A)    5.3×10−135.3 	imes 10 ^ { - 13 }5.3×10−13 
B)    5.2×1045.2 	imes 10 ^ { 4 }5.2×104 
C)    1.9×10121.9 	imes 10 ^ { 12 }1.9×1012 
D)    1.9×10−51.9 	imes 10 ^ { - 5 }1.9×10−5 
E)    1.8×10−491.8 	imes 10 ^ { - 49 }1.8×10−49F) B) and C)
G) A) and D)

Exam 19: Principles of Chemical Reactivity: Entropy and Free Energy

At what temperatures will a reaction be spontaneous if Δ_rH° = +117 kJ and Δ_rS° = -35 J/K?

Correct Answer
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Which of the following is true of the deposition of a gaseous substance?

Correct Answer
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_____ changes only occur in the direction that leads toward chemical equilibrium.

Correct Answer
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A flask containing helium gas is released into a closed room. Which of the following ideas concerning entropy is/are true?

Correct Answer
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If Δ_rG° > 0 for a reaction at all temperatures, then Δ_rH° is _____ and Δ_rS° is _____.

Correct Answer
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What is the sign of ΔH (system) and ΔS (system) if a chemical reaction is spontaneous only at lower temperatures under standard conditions?

Correct Answer
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Correct Answer
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What is the equilibrium constant for reaction below at 25 °C? (R = 8.314 J/K?mol) 2 NO(g) + O₂(g) $\leftrightharpoons$ 2 NO₂(g) ; ?_fG° [NO(g) ] = +86.6 kJ/mol and ?_fG° [NO₂(g) ] = +51.2 kJ/mol.

Correct Answer
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Which of the following linear chain alcohols is likely to have the highest standard entropy in the liquid state?

Correct Answer
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For which of the following reactions will the entropy of a system decrease?

Correct Answer
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Which of the following compounds has the highest standard entropy per mole at 298 K?

Correct Answer
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The total entropy of the universe is always increasing. This is a statement of the _____ law of thermodynamics.

Correct Answer
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At a temperature (in kelvin units) of _____, the entropy of a pure crystal is 0.0 J/K.

Correct Answer
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Correct Answer
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For which of the following substances is the standard free energy of formation not equal to zero at 298 K?

Correct Answer
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For a certain reversible process, q = 88.06 kJ at 29.4°C. Which of the following is the ΔS for the process?

Correct Answer
verified

At what temperatures will a reaction be spontaneous if Δ_rH° = +62.4 kJ and Δ_rS° = +301 J/K?

Correct Answer
verified

Given the following data: S(g) + O₂(g) → SO₂(g) Δ_rG° = -300.1 kJ/mol-rxn 2 S(g) + 3 O₂(g) → 2 SO₃(g) Δ_rG° = -742.1 kJ/mol-rxn Calculate Δ_fG° for the reaction below. SO₂(g) + 1/2 O₂(g) → SO₃(g)

Correct Answer
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A 100 mL sample of water is placed in a coffee cup calorimeter. When 1.0 g of an ionic solid is added, the temperature decreases from 21.5 °C to 20.8 °C as the solid dissolves. For the dissolving of the solid, _____.

Correct Answer
verified

Which of the following relationships is not true?

Correct Answer
verified

Exam 19: Principles of Chemical Reactivity: Entropy and Free Energy

At what temperatures will a reaction be spontaneous if ΔrH° = +117 kJ and ΔrS° = -35 J/K?

Correct AnswerverifiedShow Answer

Which of the following is true of the deposition of a gaseous substance?

Correct AnswerverifiedShow Answer

_____ changes only occur in the direction that leads toward chemical equilibrium.

Correct AnswerverifiedShow Answer

A flask containing helium gas is released into a closed room. Which of the following ideas concerning entropy is/are true?

Correct AnswerverifiedShow Answer

If ΔrG° > 0 for a reaction at all temperatures, then ΔrH° is _____ and ΔrS° is _____.

Correct AnswerverifiedShow Answer

What is the sign of ΔH (system) and ΔS (system) if a chemical reaction is spontaneous only at lower temperatures under standard conditions?

Correct AnswerverifiedShow Answer

Correct AnswerverifiedShow Answer

What is the equilibrium constant for reaction below at 25 °C? (R = 8.314 J/K?mol) 2 NO(g) + O2(g) ⇋\leftrightharpoons⇋ 2 NO2(g) ; ?fG° [NO(g) ] = +86.6 kJ/mol and ?fG° [NO2(g) ] = +51.2 kJ/mol.

Correct AnswerverifiedShow Answer

Which of the following linear chain alcohols is likely to have the highest standard entropy in the liquid state?

Correct AnswerverifiedShow Answer

For which of the following reactions will the entropy of a system decrease?

Correct AnswerverifiedShow Answer

Which of the following compounds has the highest standard entropy per mole at 298 K?

Correct AnswerverifiedShow Answer

The total entropy of the universe is always increasing. This is a statement of the _____ law of thermodynamics.

Correct AnswerverifiedShow Answer

At a temperature (in kelvin units) of _____, the entropy of a pure crystal is 0.0 J/K.

Correct AnswerverifiedShow Answer

Correct AnswerverifiedShow Answer

For which of the following substances is the standard free energy of formation not equal to zero at 298 K?

Correct AnswerverifiedShow Answer

For a certain reversible process, q = 88.06 kJ at 29.4°C. Which of the following is the ΔS for the process?

Correct AnswerverifiedShow Answer

At what temperatures will a reaction be spontaneous if ΔrH° = +62.4 kJ and ΔrS° = +301 J/K?

Correct AnswerverifiedShow Answer

Given the following data: S(g) + O2(g) → SO2(g) ΔrG° = -300.1 kJ/mol-rxn 2 S(g) + 3 O2(g) → 2 SO3(g) ΔrG° = -742.1 kJ/mol-rxn Calculate ΔfG° for the reaction below. SO2(g) + 1/2 O2(g) → SO3(g)

Correct AnswerverifiedShow Answer

A 100 mL sample of water is placed in a coffee cup calorimeter. When 1.0 g of an ionic solid is added, the temperature decreases from 21.5 °C to 20.8 °C as the solid dissolves. For the dissolving of the solid, _____.

Correct AnswerverifiedShow Answer

Which of the following relationships is not true?

Correct AnswerverifiedShow Answer

At what temperatures will a reaction be spontaneous if Δ_rH° = +117 kJ and Δ_rS° = -35 J/K?

Correct Answer
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Correct Answer
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Correct Answer
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Correct Answer
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If Δ_rG° > 0 for a reaction at all temperatures, then Δ_rH° is _____ and Δ_rS° is _____.

Correct Answer
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Correct Answer
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Correct Answer
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What is the equilibrium constant for reaction below at 25 °C? (R = 8.314 J/K?mol) 2 NO(g) + O₂(g) $\leftrightharpoons$ 2 NO₂(g) ; ?_fG° [NO(g) ] = +86.6 kJ/mol and ?_fG° [NO₂(g) ] = +51.2 kJ/mol.

Correct Answer
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Correct Answer
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Correct Answer
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Correct Answer
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Correct Answer
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Correct Answer
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Correct Answer
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At what temperatures will a reaction be spontaneous if Δ_rH° = +62.4 kJ and Δ_rS° = +301 J/K?

Correct Answer
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Given the following data: S(g) + O₂(g) → SO₂(g) Δ_rG° = -300.1 kJ/mol-rxn 2 S(g) + 3 O₂(g) → 2 SO₃(g) Δ_rG° = -742.1 kJ/mol-rxn Calculate Δ_fG° for the reaction below. SO₂(g) + 1/2 O₂(g) → SO₃(g)

Correct Answer
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Correct Answer
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Correct Answer
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