Question 1

Which of these species has the highest entropy (S^$\circ$) at 25^$\circ$C

Accepted Answer

Entropy is a measure of disorder/randomness of a system. It is given by the formula S=k ln(W) where k is the Boltzmann constant and W is the number of microstates that a system can have. The gas state (CO) has the highest entropy because gases have the most degrees of freedom and therefore the most number of microstates. The other species are either in a liquid or solid state, which have lower entropy values.

Question 2

Aluminum forms a layer of aluminum oxide when exposed to air which protects the bulk metal from further corrosion.4Al(s) + 3O₂(g) $\rarr$ 2Al₂O₃(s) Using the thermodynamic data provided below, calculate $\Delta$S^$\circ$ for this reaction. $\begin{array}{|l|c|} \hline & \mathrm{S}^{\circ}(\mathrm{J} / \mathrm{K} \cdot \mathrm{~mol}) \ \hline \mathrm{Al}(s) & 28.3 \ \hline \mathrm{O}_{2}(g) & 205.0 \ \hline \mathrm{Al}_{2} \mathrm{O}_{3}(s) & 50.99 \ \hline \end{array}$

Accepted Answer

D

Question 3

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

Accepted Answer

The greater the number of atoms and/or the complexity of the molecule, the higher the entropy. E has the most atoms and is the most complex molecule among the given options, hence it has the highest standard entropy.

Question 4

Which of the following processes would be accompanied by a decrease in entropy

Accepted Answer

Entropy decreases when a system goes from a more disordered state to a more ordered state, such as from gas (high entropy) to solid (low entropy).

Question 5

Which of the following processes would be accompanied by an increase in entropy

Accepted Answer

The process described in D involves a phase change from solid to gas, which increases entropy due to the greater freedom of movement and higher disorder in the gas phase compared to the solid phase.

Question 6

Without reference to a table, arrange these reactions according to increasing $\Delta$S. 1) CH₄(g) + H₂O(g) $\rarr$ CO(g) + 3H₂(g) 2) C(s) + O₂(g) $\rarr$CO₂(g) 3) H₂O₂(l) $\rarr$ H₂O(l) + ¹/₂O₂(g)

Accepted Answer

The answer of Without reference to a table, arrange these...

Question 7

Which response includes all the following processes that are accompanied by an increase in entropy 1) 2SO₂(g) + O₂(g) $\rarr$ SO₃(g) 2) H₂O(l) $\rarr$H₂O(s) 3) Br₂(l) $\rarr$Br₂(g) 4) H₂O₂(l) $\rarr$ H₂O(l) + ¹/₂O₂(g)

Accepted Answer

Entropy increases when a system becomes more disordered or spread out. Processes 3 and 4 involve a change from a less dispersed state (liquid) to a more dispersed state (gas) and from a single phase to multiple phases, respectively, both of which increase entropy. Process 2, involving freezing, decreases entropy, and the formatting errors in option 1 make it unclear, but typically, gas reactions without a change in the number of gas molecules do not significantly change entropy.

Question 8

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

Accepted Answer

The solid state has lower entropy compared to gases or liquids, hence the species in solid state, i.e. iodine, would have the lowest standard entropy.

Question 9

Which response includes all of the following processes that are accompanied by an increase in entropy 1) I₂(s) $\rarr$I₂(g) 2) 2I(g) $\rarr$ I₂(g) 3) 2NH₃(g) $\rarr$ N₂(g) + 3H₂(g) 4) Mg²⁺(aq) + 2OH^-(aq) $\rarr$Mg(OH)₂(s)

Accepted Answer

Processes 1 and 3 both involve a gas being produced, which increases entropy. The other two processes involve a solid forming, which decreases entropy.

Question 10

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

The answer of Which response includes all of the following...

Question 11

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

The answer of Sulfur can be separated from lead in...

Question 12

Which one of the following reactions would you expect to have the lowest $\Delta$S^$\circ$

Accepted Answer

The ΔH value is the lowest for reaction B because it involves weaker bonds being broken and formed compared to the other reactions. Specifically, in reaction B, the C-H bond and the S-O bond are broken and the C=O bond is formed, which are all relatively weak compared to the bonds involved in the other reactions.

Question 13

Which of these species has the highest entropy (S^$\circ$) at 25^$\circ$C

Accepted Answer

Entropy is a measure of disorder or randomness. Gases generally have higher entropy than liquids and solids. Among the gases, CH₄(g) has more atoms and complexity than CO(g), leading to higher entropy.

Question 14

Which one of the following reactions would you expect to have highest $\Delta$S^$\circ$

Accepted Answer

The answer of Which one of the following reactions would...

Question 15

Arrange the following substances in the order of increasing entropy at 25^$\circ$C.HF(g), NaF(s), SiF₄(g), SiH₄(g), Al(s) lowest $\rarr$ highest

Accepted Answer

Entropy generally increases from solids to liquids to gases, and within gases, more complex molecules have higher entropy. Al(s) is a solid with a simple structure, thus has the lowest entropy. NaF(s) is also a solid but more complex than a pure metal. HF(g) is a simple diatomic gas, so its entropy is higher than that of solids. SiH4(g) and SiF4(g) are both gases, but SiF4(g) is more complex due to the presence of fluorine atoms, making its entropy the highest.

Question 16

Determine $\Delta$S^$\circ$ for the reaction SO₃(g) + H₂O(l) $\rarr$ H₂SO₄(l). $\begin{array}{lc} &\mathrm{S}^{\circ}(\mathrm{J} / \mathrm{K} \cdot \mathrm{~mol})\\hline \mathrm{SO}_{3} & 256.2 \ \mathrm{H}_{2} \mathrm{O} & 69.9 \ \mathrm{H}_{2} \mathrm{SO}_{4} & 156.9 \end{array}$

Accepted Answer

We can use Hess's Law to determine the enthalpy change for the reaction. First, we need to reverse the direction of the last reaction and change the sign of its enthalpy change: H₂SO₄(l) → SO₃(g) + H₂O(l) ΔH° = -F1F1F10 Next, we can use the enthalpy changes for the following reactions: SO₃(g) + O2(g) → SO₄(l) ΔH° = -F1F1F1S1 H₂O(l) + O2(g) → HO2₂O(l) ΔH° = -SF1F1F1 SO₃(g) + HO2₂O(l) → SO₄(l) + O2(g) + H2O(l) ΔH° = -F1F1F1S1 By adding these reactions, we get: SO₃(g) + H₂O(l) → SO₄(l) ΔH° = -F1F1F1S1 - SF1F1F1 - F1F1F1S1 = -169.2 J/K·mol Therefore, the answer is C.

Question 17

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

Accepted Answer

HF is a diatomic molecule, which means it has a simple structure and only one possible orientation, resulting in lower standard entropy. The other species are larger and more complex, allowing for greater degrees of freedom and higher standard entropy.

Question 18

Arrange these compounds in order of increasing standard molar entropy at 25^$\circ$C: C₃H₈(g), C₂H₄(g), ZnS(s), and H₂O(l).

Accepted Answer

Entropy generally increases from solids to liquids to gases, and among gases, it increases with molecular complexity and mass. ZnS (solid) has the lowest entropy, followed by H2O (liquid), then CH4 (simple gas), and finally C2H6 (more complex gas).

Question 19

Which of the following is expected to have zero entropy I. N₂(g) at 273 K II. SiO₂(s, amorphous) at 0 K III. NaCl(s) perfectly ordered crystal at 25 K IV. Na(s) perfectly ordered crystal at 0 K

Accepted Answer

Entropy measures the disorder or randomness in a system. According to the third law of thermodynamics, the entropy of a perfect crystal at absolute zero (0 K) is exactly zero because the system is in a state of perfect order. Among the options, only IV (Na(s) perfectly ordered crystal at 0 K) meets this criterion. All other options involve conditions or substances that do not meet the criteria for having zero entropy.

Question 20

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

Reaction 1 involves a decrease in entropy as gas condenses to liquid. Reaction 2 involves an increase in entropy as two moles of gas form from two moles of gas. Reaction 3 involves a significant increase in entropy as a solid decomposes to form a gas.

Quiz 17: Entropy Free Energy and Equilibrium

Which of these species has the highest entropy (S^$\circ$) at 25^$\circ$C

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

Which of the following processes would be accompanied by a decrease in entropy

Which of the following processes would be accompanied by an increase in entropy

Without reference to a table, arrange these reactions according to increasing $\Delta$ S. 1) CH₄(g) + H₂O(g) $\rarr$ CO(g) + 3H₂(g) 2) C(s) + O₂(g) $\rarr$ CO₂(g) 3) H₂O₂(l) $\rarr$ H₂O(l) + ¹/₂O₂(g)

Which response includes all the following processes that are accompanied by an increase in entropy 1) 2SO₂(g) + O₂(g) $\rarr$ SO₃(g) 2) H₂O(l) $\rarr$ H₂O(s) 3) Br₂(l) $\rarr$ Br₂(g) 4) H₂O₂(l) $\rarr$ H₂O(l) + ¹/₂O₂(g)

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

Which response includes all of the following processes that are accompanied by an increase in entropy 1) I₂(s) $\rarr$ I₂(g) 2) 2I(g) $\rarr$ I₂(g) 3) 2NH₃(g) $\rarr$ N₂(g) + 3H₂(g) 4) Mg²⁺(aq) + 2OH^-(aq) $\rarr$ Mg(OH) ₂(s)

Which one of the following reactions would you expect to have the lowest $\Delta$ S^$\circ$

Which of these species has the highest entropy (S^$\circ$) at 25^$\circ$C

Which one of the following reactions would you expect to have highest $\Delta$ S^$\circ$

Arrange the following substances in the order of increasing entropy at 25^$\circ$C.HF(g) , NaF(s) , SiF₄(g) , SiH₄(g) , Al(s) lowest $\rarr$ highest

Determine $\Delta$ S^$\circ$ for the reaction SO₃(g) + H₂O(l) $\rarr$ H₂SO₄(l) . $\begin{array}{lc}&\mathrm{S}^{\circ}(\mathrm{J} / \mathrm{K} \cdot \mathrm{~mol}) \\\hline\mathrm{SO}_{3} & 256.2 \\\mathrm{H}_{2} \mathrm{O} & 69.9 \\\mathrm{H}_{2} \mathrm{SO}_{4} & 156.9\end{array}$

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

Arrange these compounds in order of increasing standard molar entropy at 25^$\circ$C: C₃H₈(g) , C₂H₄(g) , ZnS(s) , and H₂O(l) .

Which of the following is expected to have zero entropy I. N₂(g) at 273 K II. SiO₂(s, amorphous) at 0 K III. NaCl(s) perfectly ordered crystal at 25 K IV. Na(s) perfectly ordered crystal at 0 K

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)

Quiz 17: Entropy Free Energy and Equilibrium

Which of these species has the highest entropy (S ∘\circ∘ ) at 25 ∘\circ∘ C

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

Which of the following processes would be accompanied by a decrease in entropy

Which of the following processes would be accompanied by an increase in entropy

Without reference to a table, arrange these reactions according to increasing Δ\DeltaΔ S. 1) CH4(g) + H2O(g) →\rarr→ CO(g) + 3H2(g) 2) C(s) + O2(g) →\rarr→ CO2(g) 3) H2O2(l) →\rarr→ H2O(l) + 1/2O2(g)

Which response includes all the following processes that are accompanied by an increase in entropy 1) 2SO2(g) + O2(g) →\rarr→ SO3(g) 2) H2O(l) →\rarr→ H2O(s) 3) Br2(l) →\rarr→ Br2(g) 4) H2O2(l) →\rarr→ H2O(l) + 1/2O2(g)

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

Which response includes all of the following processes that are accompanied by an increase in entropy 1) I2(s) →\rarr→ I2(g) 2) 2I(g) →\rarr→ I2(g) 3) 2NH3(g) →\rarr→ N2(g) + 3H2(g) 4) Mg2+(aq) + 2OH-(aq) →\rarr→ Mg(OH) 2(s)

Which one of the following reactions would you expect to have the lowest Δ\DeltaΔ S ∘\circ∘

Which of these species has the highest entropy (S ∘\circ∘ ) at 25 ∘\circ∘ C

Which one of the following reactions would you expect to have highest Δ\DeltaΔ S ∘\circ∘

Arrange the following substances in the order of increasing entropy at 25 ∘\circ∘ C.HF(g) , NaF(s) , SiF4(g) , SiH4(g) , Al(s) lowest →\rarr→ highest

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

Arrange these compounds in order of increasing standard molar entropy at 25 ∘\circ∘ C: C3H8(g) , C2H4(g) , ZnS(s) , and H2O(l) .

Which of the following is expected to have zero entropy I. N2(g) at 273 K II. SiO2(s, amorphous) at 0 K III. NaCl(s) perfectly ordered crystal at 25 K IV. Na(s) perfectly ordered crystal at 0 K

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)

Which of these species has the highest entropy (S^$\circ$) at 25^$\circ$C

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

Without reference to a table, arrange these reactions according to increasing $\Delta$ S. 1) CH₄(g) + H₂O(g) $\rarr$ CO(g) + 3H₂(g) 2) C(s) + O₂(g) $\rarr$ CO₂(g) 3) H₂O₂(l) $\rarr$ H₂O(l) + ¹/₂O₂(g)

Which response includes all the following processes that are accompanied by an increase in entropy 1) 2SO₂(g) + O₂(g) $\rarr$ SO₃(g) 2) H₂O(l) $\rarr$ H₂O(s) 3) Br₂(l) $\rarr$ Br₂(g) 4) H₂O₂(l) $\rarr$ H₂O(l) + ¹/₂O₂(g)

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

Which response includes all of the following processes that are accompanied by an increase in entropy 1) I₂(s) $\rarr$ I₂(g) 2) 2I(g) $\rarr$ I₂(g) 3) 2NH₃(g) $\rarr$ N₂(g) + 3H₂(g) 4) Mg²⁺(aq) + 2OH^-(aq) $\rarr$ Mg(OH) ₂(s)

Which one of the following reactions would you expect to have the lowest $\Delta$ S^$\circ$

Which of these species has the highest entropy (S^$\circ$) at 25^$\circ$C

Which one of the following reactions would you expect to have highest $\Delta$ S^$\circ$

Arrange the following substances in the order of increasing entropy at 25^$\circ$C.HF(g) , NaF(s) , SiF₄(g) , SiH₄(g) , Al(s) lowest $\rarr$ highest

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

Arrange these compounds in order of increasing standard molar entropy at 25^$\circ$C: C₃H₈(g) , C₂H₄(g) , ZnS(s) , and H₂O(l) .

Which of the following is expected to have zero entropy I. N₂(g) at 273 K II. SiO₂(s, amorphous) at 0 K III. NaCl(s) perfectly ordered crystal at 25 K IV. Na(s) perfectly ordered crystal at 0 K

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)