Question 1

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

Question 2

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

Question 3

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  0 
C)  ΔS(system)  0 
E)  None of these 
A)  ΔH  0 
C)  ΔS(system)  0 
E)  None of these

Question 4

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 5

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-rxn 
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-rxn

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

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

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

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)  CH3CH2CH2CH2CH2OH 
A)  CH3OH 
B)  CH3CH2OH 
C)  CH3CH2CH2OH 
D)  CH3CH2CH2CH2OH 
E)  CH3CH2CH2CH2CH2OH

Question 10

Which of the following relationships is not true?

Accepted Answer

A)  $\Delta G _ { \text {sys } } ^ { \circ } = \Delta H _ { \text {sys } } ^ { \circ } - T \Delta S _ { \text {sys } } ^ { \circ }$ 
B)  $\Delta G _ { \text {sys } } ^ { \circ } = - R T \ln ( K )$ 
C)  $\Delta S _ { \text {univ } } ^ { \circ} = \Delta S _ { \text {sys } } ^ { \circ } + \Delta S _ { \text {surr } } ^ { \circ }$ 
D)  $\Delta H = \Delta H _ { \text {sys }}^{\circ} + R T \ln ( K )$ 
E)  $\Delta G _ { \text {sys } } ^ { \circ } = - T \Delta S _ { \text {univ } } ^ { \circ }$ 
A)  $\Delta G _ { \text {sys } } ^ { \circ } = \Delta H _ { \text {sys } } ^ { \circ } - T \Delta S _ { \text {sys } } ^ { \circ }$ 
B)  $\Delta G _ { \text {sys } } ^ { \circ } = - R T \ln ( K )$ 
C)  $\Delta S _ { \text {univ } } ^ { \circ} = \Delta S _ { \text {sys } } ^ { \circ } + \Delta S _ { \text {surr } } ^ { \circ }$ 
D)  $\Delta H = \Delta H _ { \text {sys }}^{\circ} + R T \ln ( K )$ 
E)  $\Delta G _ { \text {sys } } ^ { \circ } = - T \Delta S _ { \text {univ } } ^ { \circ }$

Question 11

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. 
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.

Question 12

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)
$\begin{array}{ll}
\text { Substance } & \underline{\Delta}_{\mathrm{f}} \mathrm{G}^{\circ}(\mathrm{kJ} / \mathrm{mol}) \text { at } 298 \mathrm{~K} \
\hline
\mathrm{Br}-(\mathrm{aq}) & -104.0 \
\mathrm{Ag}^{+}(\mathrm{aq}) & 77.12 \
\mathrm{AgBr}(\mathrm{s}) & -96.9
\end{array}$

Accepted Answer

A)  $5.3 \times 10 ^ { - 13 }$ 
B)  $5.2 \times 10 ^ { 4 }$ 
C)  $1.9 \times 10 ^ { 12 }$ 
D)  $1.9 \times 10 ^ { - 5 }$ 
E)  $1.8 \times 10 ^ { - 49 }$ 
A)  $5.3 \times 10 ^ { - 13 }$ 
B)  $5.2 \times 10 ^ { 4 }$ 
C)  $1.9 \times 10 ^ { 12 }$ 
D)  $1.9 \times 10 ^ { - 5 }$ 
E)  $1.8 \times 10 ^ { - 49 }$

Question 13

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

Question 14

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

Question 15

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 spontaneous 
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 spontaneous

Question 16

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

Question 17

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 these 
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 these

Question 18

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 negative 
A)  Negative; positive 
B)  Positive; negative 
C)  Negative; negative 
D)  Positive; positive 
E)  Positive; either positive or negative

Question 19

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)
$$\begin{array} { l l l } 
\text { Species } & \Delta _f H ^ { \circ } ( \mathrm { kJ } / \mathrm { mol } ) & S ^ { \circ } ( \mathrm { J } / \mathrm { K } \cdot \mathrm { mol } ) \
\hline \mathrm { Fe } ( \mathrm { s } ) & 0.0 & 27.8 \
\mathrm { O } _ { 2 } ( \mathrm {~g} ) & 0.0 & 205.1 \
\mathrm { Fe } _ { 3 } \mathrm { O } _ { 4 } ( \mathrm {~s} ) & - 1118.4 & 146.4
\end{array}$$

Accepted Answer

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

Question 20

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) 
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)

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

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

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.

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, _____.

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

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)

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

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

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

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

Which of the following relationships is not true?

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

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 (/) at 298 -() -104.0 () 77.12 () -96.9

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

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

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

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

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

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

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 (/) (/\cdot) () 0.0 27.8 () 0.0 205.1 () -1118.4 146.4

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

Basic Concepts of Chemistry

Lets Review: the Tools of Quantitative Chemistry

Atoms, Molecules, and Ions

Chemical Reactions

Stoichiometry: Quantitative Information About Chemical Reactions

Principles of Chemical Reactivity: Energy and Chemical Reactions

The Structure of Atoms

The Structure of Atoms and Periodic Trends

Bonding and Molecular Structure

Bonding and Molecular Structure Orbital Hybridization and Molecular Orbitals

Gases and Their Properties

Intermolecular Forces and Liquids

The Solid State

Solutions and Their Behavior

Chemical Kinetics: the Rates of Chemical Reactions

Principles of Chemical Reactivity: Equilibria

Principles of Chemical Reactivity: the Chemistry of Acids and Bases

Principles of Chemical Reactivity: Other Aspects of Aqueous Equilibria

Principles of Chemical Reactivity: Electron Transfer Reactions

Environmental Chemistry: Earths Environment, Energy, and Sustainability

The Chemistry of the Main Group Elements

The Chemistry of the Transition Elements

Carbon: Not Just Another Element

Biochemistry

Nuclear Chemistry

Filters

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.

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)

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

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 (/) at 298 -() -104.0 () 77.12 () -96.9

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

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

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 (/) (/\cdot) () 0.0 27.8 () 0.0 205.1 () -1118.4 146.4