Question 1

Dissolving an ionic solid in water always results in an increase in entropy.

Accepted Answer

A) True 
 B)False  False

Question 2

Calculate $\Delta$G$\circ$ for the reaction 3NO2(g) + H2O(l) $\rarr$ 2HNO3(l) + NO(g). $\begin{array}{lc}
&\Delta \mathrm{G}^{\circ}_\mathrm{f}(\mathrm{~kJ} / \mathrm{mol})\\hline
\mathrm{H}_{2} \mathrm{O}(\mathrm{l}) & -237.2 \
\mathrm{HNO}_{3}(\mathrm{l}) & -79.9 \
\mathrm{NO}{(\mathrm{g}}) & 86.7 \
\mathrm{NO}_{2}(\mathrm{g}) & 51.8
\end{array}$

Accepted Answer

A)  8.7 kJ/mol 
B)  192 kJ/mol 
C)  -414 kJ/mol 
D)  -192 kJ/mol 
E)  -155 kJ/mol 
A)  8.7 kJ/mol 
B)  192 kJ/mol 
C)  -414 kJ/mol 
D)  -192 kJ/mol 
E)  -155 kJ/mol A

Question 3

For the reaction CuS(s) + H2(g) $\leftrightharpoons$ H2S(g) + Cu(s), 
$\Delta$G$\circ$f (CuS) = -53.6 kJ/mol
$\Delta$G$\circ$f (H2S) = -33.6 kJ/mol
$\Delta$H$\circ$f (CuS) = -53.1 kJ/mol
$\Delta$H$\circ$f (H2S) = -20.6 kJ/mol
Calculate the value of the equilibrium constant (Kp) at 798 K and 1 atm pressure.

Accepted Answer

A)  1.77 
B)  1.57 
C)  1.37 
D)  1.17 
E)  None of the above 
A)  1.77 
B)  1.57 
C)  1.37 
D)  1.17 
E)  None of the above D

Question 4

Which response includes all of the following processes that are accompanied by an increase of entropy I) $ \mathrm{NaCl}(\mathrm{s}) \xrightarrow{\mathrm{H}_{2} \mathrm{O}} \mathrm{Na}^{+}(\mathrm{aq})+\mathrm{Cl}^{-}(\mathrm{aq}) $
II) $ \mathrm{CaSO}_{4}(\mathrm{s}) \xrightarrow{\mathrm{H}_{2} \mathrm{O}} \mathrm{Ca}^{2+}(\mathrm{aq})+\mathrm{SO}_{4}{ }^{2-}(\mathrm{aq}) $
III) $ \mathrm{KNO}_{3}(\mathrm{s}) \xrightarrow{\mathrm{H}_{2} \mathrm{O}} \mathrm{K}^{+}(\mathrm{aq})+\mathrm{NO}_{3}^{-}(\mathrm{aq}) $

Accepted Answer

A)  I and III 
B)  II and III 
C)  I, II and III 
D)  II only 
E)  III only 
A)  I and III 
B)  II and III 
C)  I, II and III 
D)  II only 
E)  III only

Question 5

The reaction 3H2(g) + N2(g) $\leftrightharpoons$ 2NH3(g), Kc = 9.0 at 350$\circ$C proceeds from right to left when 1.0 mol NH3, 5.0 mol N2, and 5.0 mol H2 are mixed in a 2.5 L reactor.

Accepted Answer

A) True 
 B)False

Question 6

Find the temperature at which Kp = 4.00 for the reaction N2O4(g) $\leftrightharpoons$ 2NO2(g). [Given: at 25$\circ$C, for NO2(g), $\Delta$H$\circ$f = 33.85 kJ/mol, S$\circ$ = 240.46 J/mol·K; for N2O4(g), $\Delta$H$\circ$f = 9.66 kJ/mol, S$\circ$ = 304.3 J/mol·K; assume that $\Delta$H$\circ$ and $\Delta$S$\circ$ are independent of temperature.]

Accepted Answer

A)  197 $\circ$C 
B)  56 $\circ$C 
C)  36 $\circ$C 
D)  79 $\circ$C 
E)  476$\circ$C 
A)  197 $\circ$C 
B)  56 $\circ$C 
C)  36 $\circ$C 
D)  79 $\circ$C 
E)  476$\circ$C

Question 7

Sulfur can be separated from lead in the mineral galena, PbS(s), by "roasting" the ore in the presence of oxygen as shown in the following reaction: 2PbS(s) + 3O2(g) $\rarr$ 2PbO(s) + 2SO2(g)
Calculate $\Delta$S$\circ$ for this reaction using the thermodynamic data provided below. $\begin{array}{|l|c|}
\hline & \mathrm{S}^{\circ}(\mathrm{J} / \mathrm{K} \cdot \mathrm{~mol}) \
\hline \mathrm{PbS}(s) & 91.2 \
\hline \mathrm{O}_{2}(g) & 205.0 \
\hline \mathrm{PbO}(s) & 69.45 \
\hline \mathrm{SO}_{2}(g) & 248.5 \
\hline
\end{array}$

Accepted Answer

A)  -410 J/K·mol 
B)  -161.5 J/K·mol 
C)  -47.7 J/K·mol 
D)  21.8 J/K·mol 
E)  43.5 J/K·mol 
A)  -410 J/K·mol 
B)  -161.5 J/K·mol 
C)  -47.7 J/K·mol 
D)  21.8 J/K·mol 
E)  43.5 J/K·mol

Question 8

What is the free energy change for the reaction SiO2(s) + Pb(s) $\rarr$PbO2(s) + Si(s)
$\Delta$G$\circ$f (PbO2) = -217 kJ/mol
$\Delta$G$\circ$f (SiO2) = -856 kJ/mol

Accepted Answer

A)  619 kJ/mol 
B)  639 kJ/mol 
C)  659 kJ/mol 
D)  679 kJ/mol 
E)  None of the above 
A)  619 kJ/mol 
B)  639 kJ/mol 
C)  659 kJ/mol 
D)  679 kJ/mol 
E)  None of the above

Question 9

Given the following data, calculate the boiling point of HCOOH (formic acid). $\begin{array}{lcc} 
& \underline{\Delta \mathrm{H}^{\circ}_\mathrm{f}(\mathrm{~kJ} / \mathrm{mol})} & \underline{\mathrm{S}^{\circ}(\mathrm{J} / \mathrm{K} \cdot \mathrm{~mol})} \
\mathrm{HCOOH}(\mathrm{l}) & -410 & 130\
\mathrm{HCOOH}(\mathrm{g}) & -363 & 251
\end{array}$

Accepted Answer

A)  115$\circ$C 
B)  125$\circ$C 
C)  145$\circ$C 
D)  165$\circ$C 
E)  None of the above 
A)  115$\circ$C 
B)  125$\circ$C 
C)  145$\circ$C 
D)  165$\circ$C 
E)  None of the above

Question 10

Consider the reaction CO(g) + 2H2(g) $\leftrightharpoons$ CH3OH(l) at 25$\circ$C.
$\Delta$G$\circ$f (CO) = -137.3 kJ/mol 
$\Delta$G$\circ$f (CH3OH) = -166.3 kJ/mol
$\Delta$H$\circ$f (CO) = -110.5 kJ/mol
$\Delta$H$\circ$f (CH3OH) = -238.7 kJ/mol
S$\circ$(CO) = 197.9 J/K·mol
S$\circ$(CH3OH) = 126.8 J/K·mol
Calculate S$\circ$(H2(g)).

Accepted Answer

A)  101 J/K·mol 
B)  131 J/K·mol 
C)  151 J/K·mol 
D)  171 J/K·mol 
E)  None of the above 
A)  101 J/K·mol 
B)  131 J/K·mol 
C)  151 J/K·mol 
D)  171 J/K·mol 
E)  None of the above

Question 11

The reaction: 6CO2(g) + 6H2O(g) $\rarr$C6H12O6(g) + 6O2(g) is never expected to be spontaneous.

Accepted Answer

A) True 
 B)False

Question 12

Which of these species would you expect to have the lowest standard entropy (S$\circ$)

Accepted Answer

A)  CH4(g) 
B)  HF(g) 
C)  NH3(g) 
D)  H2O(g) 
A)  CH4(g) 
B)  HF(g) 
C)  NH3(g) 
D)  H2O(g)

Question 13

The normal boiling point of acetic acid is 118.1$\circ$C. If a sample of the acetic acid is at 125.2$\circ$C, predict the signs of $\Delta$H, $\Delta$S, and $\Delta$G for the boiling process at this temperature.

Accepted Answer

A)  ($\Delta$H) > 0, $\Delta$S > 0, $\Delta$G  0, $\Delta$S > 0, $\Delta$G > 0 
C)  ($\Delta$H) > 0, $\Delta$S  0, $\Delta$G > 0 
E)  ($\Delta$H)  0 
A)  ($\Delta$H) > 0, $\Delta$S > 0, $\Delta$G  0, $\Delta$S > 0, $\Delta$G > 0 
C)  ($\Delta$H) > 0, $\Delta$S  0, $\Delta$G > 0 
E)  ($\Delta$H)  0

Question 14

Sodium carbonate can be made by heating sodium bicarbonate: 2NaHCO3(s) $\rarr$ Na2CO3(s) + CO2(g) + H2O(g)
Given that $\Delta$H$\circ$ = 128.9 kJ/mol and $\Delta$G$\circ$ = 33.1 kJ/mol at 25$\circ$C, above what minimum temperature will the reaction become spontaneous under standard state conditions

Accepted Answer

A)  0.4 K 
B)  3.9 K 
C)  321 K 
D)  401 K 
E)  525 K 
A)  0.4 K 
B)  3.9 K 
C)  321 K 
D)  401 K 
E)  525 K

Question 15

Consider the reaction CO(g) + 2H2(g) $\leftrightharpoons$ CH3OH(l) at 25$\circ$C.
$\Delta$G$\circ$f (CO) = -137.3 kJ/mol 
$\Delta$G$\circ$f (CH3OH) = -166.3 kJ/mol
$\Delta$H$\circ$f (CO) = -110.5 kJ/mol
$\Delta$H$\circ$f (CH3OH) = -238.7 kJ/mol
S$\circ$(CO) = 197.9 J/K·mol
S$\circ$(CH3OH) = 126.8 J/K·mol
Calculate the value of the equilibrium constant (Kp) for this reaction at 25$\circ$C.

Accepted Answer

A)  1.41 * 10 5 
B)  1.21* 10 5 
C)  1.01 * 10 5 
D)  1.81 * 10 4 
E)  None of the above 
A)  1.41 * 10 5 
B)  1.21* 10 5 
C)  1.01 * 10 5 
D)  1.81 * 10 4 
E)  None of the above

Question 16

For the reaction SbCl5(g) $\leftrightharpoons$ SbCl3(g) + Cl2(g), 
$\Delta$G$\circ$f (SbCl5) = -334.34 kJ/mol
$\Delta$G$\circ$f (SbCl3) = -301.25 kJ/mol
$\Delta$H$\circ$f (SbCl5) = -394.34 kJ/mol
$\Delta$H$\circ$f (SbCl3) = -313.80 kJ/mol
Calculate the value of the equilibrium constant (Kp) for this reaction at 298 K.

Accepted Answer

A)  1.38 * 10-6 
B)  1.58 * 10-6 
C)  1.78 * 10-6 
D)  1.98 * 10-6 
E)  None of the above 
A)  1.38 * 10-6 
B)  1.58 * 10-6 
C)  1.78 * 10-6 
D)  1.98 * 10-6 
E)  None of the above

Question 17

Rubidium has a heat of vaporization of 69.0 kJ/mol at its boiling point (686$\circ$C). Calculate $\Delta$S for this process, Rb(l) $\rarr$ Rb(g), at 1 atm and 686$\circ$C.

Accepted Answer

A)  65.9 J/K·mol 
B)  67.9 J/K·mol 
C)  69.9 J/K·mol 
D)  71.9 J/K·mol 
E)  None of the above 
A)  65.9 J/K·mol 
B)  67.9 J/K·mol 
C)  69.9 J/K·mol 
D)  71.9 J/K·mol 
E)  None of the above

Question 18

At a given temperature, O2(g) at 5 atm has a higher entropy per mole than O2(g) at 0.5 atm.

Accepted Answer

A) True 
 B)False

Question 19

Arrange these reactions according to increasing $\Delta$S.
1) H2O(g) $\rarr$ H2O(l) 
2) 2NO(g) $\rarr$ N2(g) + O2(g)
3) MgCO3(s) $\rarr$ MgO(s) + CO2(g)

Accepted Answer

A)  1 < 2 < 3 
B)  2 < 3 < 1 
C)  3 < 2 < 1 
D)  2 < 1 < 3 
E)  1 < 3 < 2 
A)  1 < 2 < 3 
B)  2 < 3 < 1 
C)  3 < 2 < 1 
D)  2 < 1 < 3 
E)  1 < 3 < 2

Question 20

Under the conditions of high temperatures only, the reaction O2(g) $\rarr$2O(g) would be expected to be spontaneous.

Accepted Answer

A) True 
 B)False

Dissolving an ionic solid in water always results in an increase in entropy.

Calculate $\Delta$ G^$\circ$ for the reaction 3NO₂(g) + H₂O(l) $\rarr$ 2HNO₃(l) + NO(g). \Delta(/) () -237.2 () -79.9 ( ) 86.7 () 51.8

The reaction 3H₂(g) + N₂(g) $\leftrightharpoons$ 2NH₃(g), K_c = 9.0 at 350^$\circ$C proceeds from right to left when 1.0 mol NH₃, 5.0 mol N₂, and 5.0 mol H₂ are mixed in a 2.5 L reactor.

What is the free energy change for the reaction SiO₂(s) + Pb(s) $\rarr$ PbO₂(s) + Si(s) $\Delta$ G^$\circ$_f (PbO₂) = -217 kJ/mol $\Delta$ G^$\circ$_f (SiO₂) = -856 kJ/mol

Given the following data, calculate the boiling point of HCOOH (formic acid). () -410 130 () -363 251

The reaction: 6CO₂(g) + 6H₂O(g) $\rarr$ C₆H₁₂O₆(g) + 6O₂(g) is never expected to be spontaneous.

Which of these species would you expect to have the lowest standard entropy (S^$\circ$)

The normal boiling point of acetic acid is 118.1^$\circ$C. If a sample of the acetic acid is at 125.2^$\circ$C, predict the signs of $\Delta$ H, $\Delta$ S, and $\Delta$ G for the boiling process at this temperature.

Rubidium has a heat of vaporization of 69.0 kJ/mol at its boiling point (686^$\circ$C). Calculate $\Delta$ S for this process, Rb(l) $\rarr$ Rb(g), at 1 atm and 686^$\circ$C.

At a given temperature, O₂(g) at 5 atm has a higher entropy per mole than O₂(g) at 0.5 atm.

Arrange these reactions according to increasing $\Delta$ S. 1) H₂O(g) $\rarr$ H₂O(l) 2) 2NO(g) $\rarr$ N₂(g) + O₂(g) 3) MgCO₃(s) $\rarr$ MgO(s) + CO₂(g)

Under the conditions of high temperatures only, the reaction O₂(g) $\rarr$ 2O(g) would be expected to be spontaneous.

Chemistry: The Study of Change

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Mass Relationships in Chemical Reactions

Reactions in Aqueous Solutions

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Quantum Theory and the Electronic Structure of Atoms

Periodic Relationships Among the Elements

Chemical Bonding I: Basic Concepts

Chemical Bonding II: Molecular Geometry and Hybridization of Atomic

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Exam 17: Entropy Free Energy and Equilibrium

Dissolving an ionic solid in water always results in an increase in entropy.

Calculate Δ\DeltaΔ G ∘\circ∘ for the reaction 3NO2(g) + H2O(l) →\rarr→ 2HNO3(l) + NO(g). \Delta(/) () -237.2 () -79.9 ( ) 86.7 () 51.8

The reaction 3H2(g) + N2(g) ⇋\leftrightharpoons⇋ 2NH3(g), Kc = 9.0 at 350 ∘\circ∘ C proceeds from right to left when 1.0 mol NH3, 5.0 mol N2, and 5.0 mol H2 are mixed in a 2.5 L reactor.

What is the free energy change for the reaction SiO2(s) + Pb(s) →\rarr→ PbO2(s) + Si(s) Δ\DeltaΔ G ∘\circ∘ f (PbO2) = -217 kJ/mol Δ\DeltaΔ G ∘\circ∘ f (SiO2) = -856 kJ/mol

Given the following data, calculate the boiling point of HCOOH (formic acid). () -410 130 () -363 251

The reaction: 6CO2(g) + 6H2O(g) →\rarr→ C6H12O6(g) + 6O2(g) is never expected to be spontaneous.

Which of these species would you expect to have the lowest standard entropy (S ∘\circ∘ )

The normal boiling point of acetic acid is 118.1 ∘\circ∘ C. If a sample of the acetic acid is at 125.2 ∘\circ∘ C, predict the signs of Δ\DeltaΔ H, Δ\DeltaΔ S, and Δ\DeltaΔ G for the boiling process at this temperature.

Rubidium has a heat of vaporization of 69.0 kJ/mol at its boiling point (686 ∘\circ∘ C). Calculate Δ\DeltaΔ S for this process, Rb(l) →\rarr→ Rb(g), at 1 atm and 686 ∘\circ∘ C.

At a given temperature, O2(g) at 5 atm has a higher entropy per mole than O2(g) at 0.5 atm.

Arrange these reactions according to increasing Δ\DeltaΔ S. 1) H2O(g) →\rarr→ H2O(l) 2) 2NO(g) →\rarr→ N2(g) + O2(g) 3) MgCO3(s) →\rarr→ MgO(s) + CO2(g)

Under the conditions of high temperatures only, the reaction O2(g) →\rarr→ 2O(g) would be expected to be spontaneous.

Chemistry: The Study of Change

Atoms Molecules and Ions

Mass Relationships in Chemical Reactions

Reactions in Aqueous Solutions

Gases

Thermochemistry

Quantum Theory and the Electronic Structure of Atoms

Periodic Relationships Among the Elements

Chemical Bonding I: Basic Concepts

Chemical Bonding II: Molecular Geometry and Hybridization of Atomic

Intermolecular Forces and Liquids and Solids

Physical Properties of Solutions

Chemical Kinetics

Chemical Equilibrium

Acids and Bases

Acid-Base Equilibria and Solubility Equilibria

Electrochemistry

Nuclear Chemistry

Chemistry in the Atmosphere

Metallurgy and the Chemistry of Metals

Nonmetallic Elements and Their Compounds

Transition Metals Chemistry and Coordination Compounds

Organic Chemistry

Synthetic and Natural Organic Polymers

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Calculate $\Delta$ G^$\circ$ for the reaction 3NO₂(g) + H₂O(l) $\rarr$ 2HNO₃(l) + NO(g). \Delta(/) () -237.2 () -79.9 ( ) 86.7 () 51.8

The reaction 3H₂(g) + N₂(g) $\leftrightharpoons$ 2NH₃(g), K_c = 9.0 at 350^$\circ$C proceeds from right to left when 1.0 mol NH₃, 5.0 mol N₂, and 5.0 mol H₂ are mixed in a 2.5 L reactor.

What is the free energy change for the reaction SiO₂(s) + Pb(s) $\rarr$ PbO₂(s) + Si(s) $\Delta$ G^$\circ$_f (PbO₂) = -217 kJ/mol $\Delta$ G^$\circ$_f (SiO₂) = -856 kJ/mol

The reaction: 6CO₂(g) + 6H₂O(g) $\rarr$ C₆H₁₂O₆(g) + 6O₂(g) is never expected to be spontaneous.

Which of these species would you expect to have the lowest standard entropy (S^$\circ$)

The normal boiling point of acetic acid is 118.1^$\circ$C. If a sample of the acetic acid is at 125.2^$\circ$C, predict the signs of $\Delta$ H, $\Delta$ S, and $\Delta$ G for the boiling process at this temperature.

Rubidium has a heat of vaporization of 69.0 kJ/mol at its boiling point (686^$\circ$C). Calculate $\Delta$ S for this process, Rb(l) $\rarr$ Rb(g), at 1 atm and 686^$\circ$C.

At a given temperature, O₂(g) at 5 atm has a higher entropy per mole than O₂(g) at 0.5 atm.

Arrange these reactions according to increasing $\Delta$ S. 1) H₂O(g) $\rarr$ H₂O(l) 2) 2NO(g) $\rarr$ N₂(g) + O₂(g) 3) MgCO₃(s) $\rarr$ MgO(s) + CO₂(g)

Under the conditions of high temperatures only, the reaction O₂(g) $\rarr$ 2O(g) would be expected to be spontaneous.