Question 1

Place the following in order of increasing standard molar entropy. H₂O(l)H₂O(g)H₂O(s)

Accepted Answer

Entropy increases as the substance changes from solid to liquid to gas. Therefore, the order of increasing standard molar entropy is solid < liquid < gas. The correct order for the given compounds is H₂O(s) < H₂O(l) < H₂O(g).

Question 2

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

Accepted Answer

Standard molar entropy generally increases with the complexity and size of the molecule, as well as the number of atoms and degrees of freedom (rotational, translational, vibrational). NSO (with the highest molecular complexity and number of atoms) has the highest entropy, followed by NOS, and then NO with the least complexity and fewest atoms.

Question 3

Estimate ΔG°_rxn for the following reaction at 387 K. HCN(g)+ 2 H₂(g)→ CH₃NH₂(g)ΔH° = -158.0 kJ;ΔS° = -219.9 J/K

Accepted Answer

ΔG° = ΔH° - TΔS°. Substituting the given values: ΔG° = (-158.0 kJ) - (387 K)(-219.9 J/K × 1 kJ/1000 J) = -158.0 kJ + 85.0 kJ = -72.9 kJ.

Question 4

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

Accepted Answer

The answer of Place the following in order of decreasing...

Question 5

Place the following in order of increasing molar entropy at 298 K.
NO CO SO

Accepted Answer

The answer of Place the following in order of increasing...

Question 6

Calculate ΔS°_rxn for the following reaction.The S° for each species is shown below the reaction. P₄(g)+ 10 Cl₂(g)→ 4 PCl₅(g) S°(J/mol^∙K)280.0 223.1 364.6

Accepted Answer

ΔS°_rxn = ΣS°(products) - ΣS°(reactants) = [4(364.6)] - [1(280.0) + 10(223.1)] = 1458.4 - 2511 = -1052.6 J/K.

Question 7

Place the following in order of increasing entropy at 298 K.
Ne Xe He Ar Kr

Accepted Answer

Entropy generally increases with the size and complexity of the molecule. In this case, all the substances are noble gases, so complexity is not a factor, but size is. Helium (He) is the smallest and xenon (Xe) is the largest, so entropy increases from He to Xe.

Question 8

Calculate ΔS°_rxn for the following reaction.The S° for each species is shown below the reaction. 4 NH₃(g)+ 5 O₂(g)→ 4 NO(g)+ 6 H₂O(g) S°(J/mol^∙K)192.8 205.2 210.8 188.8

Accepted Answer

The answer of Calculate ΔS°_rxn for the following reaction.The S°...

Question 9

Place the following in order of decreasing standard molar entropy. NaCl(s)Na₃PO₄(aq)NaCl(aq)

Accepted Answer

The standard molar entropy increases as the substance goes from a solid to a solution, so NaCl(s) has the lowest entropy and Na₃PO₄(aq) has the highest entropy. Therefore, Na₃PO₄(aq) has the highest entropy, followed by NaCl(aq), and then NaCl(s).

Question 10

Calculate ΔS°_rxn for the following reaction.The S° for each species is shown below the reaction. N₂H₄(l)+ H₂(g)→ 2 NH₃(g) S° (J/mol^∙K)121.2 130.7 192.8

Accepted Answer

The change in entropy (ΔS°) for a reaction is calculated by subtracting the sum of the standard molar entropies of the reactants from the sum of the standard molar entropies of the products.ΔS°_rxn = ΣS°_products - ΣS°_reactantsΔS°_rxn = [2 × S°(NH₃)] - [S°(N₂H₄) + S°(H₂)]ΔS°_rxn = [2 × 192.8 J/mol^∙K] - [121.2 J/mol^∙K + 130.7 J/mol^∙K]ΔS°_rxn = 133.7 J/mol^∙K

Question 11

Estimate ΔG°_rxn for the following reaction at 449.0 K. CH₂O(g)+ 2 H₂(g)→ CH₄(g)+ H₂O(g) ΔH° = -94.9 kJ;ΔS° = -224.2 J/K

Accepted Answer

ΔG°_rxn = ΔH° - TΔS° = -94.9 kJ - (449.0 K)(-224.2 J/K) = 5.8 kJ

Question 12

Which of the following statements is true?

Accepted Answer

The answer of Which of the following statements is true?
...

Question 13

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

Accepted Answer

The answer of Below what temperature does the following reaction...

Question 14

Calculate ?S°S1U1B1rxnS1U1B0 for the following reaction.The S° for each species is shown below the reaction.
CS1U1B12S1U1B0HS1U1B12S1U1B0(g)+ HS1U1B12S1U1B0(g)? CS1U1B12S1U1B0HS1U1B14S1U1B0(g)
S°(J/mol?K)200.9 130.7 219.3

Accepted Answer

ΔS°S1U1B1rxnS1U1B0 = ΣS°S1U1B1(products) - ΣS°S1U1B1(reactants) = [S°(CS1U1B12S1U1B0HS1U1B14S1U1B0(g)) + S°(HS1U1B12S1U1B0(g))] - [S°(CS1U1B12S1U1B0(g)) + S°(HS1U1B12S1U1B0(g))] = [(219.3 J/mol∙K) + (130.7 J/mol∙K)] - [(200.9 J/mol∙K) + (130.7 J/mol∙K)] = 338.4 J/K However, this is the change in entropy at standard conditions and not at the conditions given. To calculate the entropy change at the given conditions, we need to use the equation: ΔS = ΔS°S1U1B1rxnS1U1B0 + ΣnS1U1B1R ln(Q) where Q is the reaction quotient at the given conditions. At equilibrium, Q = K, the equilibrium constant. Since we do not have information about the concentrations of the reactants and products, we cannot directly calculate Q or K. However, we can use the information given in the answer choices to determine the sign and magnitude of ΔS. Since ΔS is a positive value at standard conditions, we can eliminate choices A and E, which have negative values. Next, we need to consider the effect of Q on ΔS. If Q < K, then ln(Q) < 0 and ΔS < ΔS°S1U1B1rxnS1U1B0. If Q > K, then ln(Q) > 0 and ΔS > ΔS°S1U1B1rxnS1U1B0. Since the reaction produces a gas (HS1U1B14S1U1B0(g)), increasing the pressure (or decreasing the volume) would shift the equilibrium towards the side with fewer moles of gas. Therefore, Q will be smaller than K at the given conditions (which are not at standard conditions). This means that ΔS will be smaller than the standard value. The only answer choice that reflects a smaller value than the standard value of 338.4 J/K is C (-112.3 J/K). Therefore, the answer is C.

Question 15

Identify the compound that is not an allotrope of carbon.

Accepted Answer

Dry ice is actually the compound carbon dioxide (CO2) in its solid form, not an allotrope of carbon.

Question 16

Place the following in order of decreasing molar entropy at 298 K. H₂ Cl₂ F₂

Accepted Answer

The answer of Place the following in order of decreasing...

Question 17

Place the following in order of increasing molar entropy at 298 K. CO₂ C₃H₈ SO

Accepted Answer

Entropy generally increases with the complexity and size of the molecule. C3H8 is the largest and most complex, followed by CO2, and then SO.

Question 18

Estimate ΔG°_rxn for the following reaction at 775 K. 2 Hg(g)+ O₂(g)→ 2 HgO(s)ΔH° = -304.2 kJ;ΔS° = -414.2 J/K

Accepted Answer

The answer of Estimate ΔG°_rxn for the following reaction at...

Question 19

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

Accepted Answer

A reversible reaction, also known as a thermodynamically equilibrium reaction, achieves the theoretical limits with respect to free energy in thermodynamics. In a reversible reaction, the forward and reverse reactions occur simultaneously and at equal rates, resulting in no net change in the concentrations of the reactants and products over time. This balance between the forward and reverse reactions leads to the maximum extent of spontaneous change in free energy, as predicted by the laws of thermodynamics.

Question 20

Calculate ΔS°_rxn for the following reaction.The S°for each species is shown below the reaction. C₂H₂(g)+ 2 H₂(g)→ C₂H₆(g) S°(J/mol^∙K)200.9 130.7 229.2

Accepted Answer

The answer of Calculate ΔS°_rxn for the following reaction.The S°^...

Quiz 17: Free Energy and Thermodynamics

Place the following in order of increasing standard molar entropy. H₂O(l) H₂O(g) H₂O(s)

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

Estimate ΔG°_rxn for the following reaction at 387 K. HCN(g) + 2 H₂(g) → CH₃NH₂(g) ΔH° = -158.0 kJ;ΔS° = -219.9 J/K

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

Place the following in order of increasing molar entropy at 298 K. NO CO SO

Calculate ΔS°_rxn for the following reaction.The S° for each species is shown below the reaction. P₄(g) + 10 Cl₂(g) → 4 PCl₅(g) S°(J/mol^∙K) 280.0 223.1 364.6

Place the following in order of increasing entropy at 298 K. Ne Xe He Ar Kr

Calculate ΔS°_rxn for the following reaction.The S° for each species is shown below the reaction. 4 NH₃(g) + 5 O₂(g) → 4 NO(g) + 6 H₂O(g) S°(J/mol^∙K) 192.8 205.2 210.8 188.8

Place the following in order of decreasing standard molar entropy. NaCl(s) Na₃PO₄(aq) NaCl(aq)

Calculate ΔS°_rxn for the following reaction.The S° for each species is shown below the reaction. N₂H₄(l) + H₂(g) → 2 NH₃(g) S° (J/mol^∙K) 121.2 130.7 192.8

Estimate ΔG°_rxn for the following reaction at 449.0 K. CH₂O(g) + 2 H₂(g) → CH₄(g) + H₂O(g) ΔH° = -94.9 kJ;ΔS° = -224.2 J/K

Which of the following statements is true?

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

Calculate ?S°_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

Identify the compound that is not an allotrope of carbon.

Place the following in order of decreasing molar entropy at 298 K. H₂ Cl₂ F₂

Place the following in order of increasing molar entropy at 298 K. CO₂ C₃H₈ SO

Estimate ΔG°_rxn for the following reaction at 775 K. 2 Hg(g) + O₂(g) → 2 HgO(s) ΔH° = -304.2 kJ;ΔS° = -414.2 J/K

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

Calculate ΔS°_rxn for the following reaction.The S°for each species is shown below the reaction. C₂H₂(g) + 2 H₂(g) → C₂H₆(g) S°(J/mol^∙K) 200.9 130.7 229.2

Quiz 17: Free Energy and Thermodynamics

Place the following in order of increasing standard molar entropy. H2O(l) H2O(g) H2O(s)

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

Estimate ΔG°rxn for the following reaction at 387 K. HCN(g) + 2 H2(g) → CH3NH2(g) ΔH° = -158.0 kJ;ΔS° = -219.9 J/K

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

Place the following in order of increasing molar entropy at 298 K. NO CO SO

Calculate ΔS°rxn for the following reaction.The S° for each species is shown below the reaction. P4(g) + 10 Cl2(g) → 4 PCl5(g) S°(J/mol∙K) 280.0 223.1 364.6

Place the following in order of increasing entropy at 298 K. Ne Xe He Ar Kr

Calculate ΔS°rxn for the following reaction.The S° for each species is shown below the reaction. 4 NH3(g) + 5 O2(g) → 4 NO(g) + 6 H2O(g) S°(J/mol∙K) 192.8 205.2 210.8 188.8

Place the following in order of decreasing standard molar entropy. NaCl(s) Na3PO4(aq) NaCl(aq)

Calculate ΔS°rxn for the following reaction.The S° for each species is shown below the reaction. N2H4(l) + H2(g) → 2 NH3(g) S° (J/mol∙K) 121.2 130.7 192.8

Estimate ΔG°rxn for the following reaction at 449.0 K. CH2O(g) + 2 H2(g) → CH4(g) + H2O(g) ΔH° = -94.9 kJ;ΔS° = -224.2 J/K

Which of the following statements is true?

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

Calculate ?S°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

Identify the compound that is not an allotrope of carbon.

Place the following in order of decreasing molar entropy at 298 K. H2 Cl2 F2

Place the following in order of increasing molar entropy at 298 K. CO2 C3H8 SO

Estimate ΔG°rxn for the following reaction at 775 K. 2 Hg(g) + O2(g) → 2 HgO(s) ΔH° = -304.2 kJ;ΔS° = -414.2 J/K

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

Calculate ΔS°rxn for the following reaction.The S° for each species is shown below the reaction. C2H2(g) + 2 H2(g) → C2H6(g) S°(J/mol∙K) 200.9 130.7 229.2

Place the following in order of increasing standard molar entropy. H₂O(l) H₂O(g) H₂O(s)

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

Estimate ΔG°_rxn for the following reaction at 387 K. HCN(g) + 2 H₂(g) → CH₃NH₂(g) ΔH° = -158.0 kJ;ΔS° = -219.9 J/K

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

Calculate ΔS°_rxn for the following reaction.The S° for each species is shown below the reaction. P₄(g) + 10 Cl₂(g) → 4 PCl₅(g) S°(J/mol^∙K) 280.0 223.1 364.6

Calculate ΔS°_rxn for the following reaction.The S° for each species is shown below the reaction. 4 NH₃(g) + 5 O₂(g) → 4 NO(g) + 6 H₂O(g) S°(J/mol^∙K) 192.8 205.2 210.8 188.8

Place the following in order of decreasing standard molar entropy. NaCl(s) Na₃PO₄(aq) NaCl(aq)

Calculate ΔS°_rxn for the following reaction.The S° for each species is shown below the reaction. N₂H₄(l) + H₂(g) → 2 NH₃(g) S° (J/mol^∙K) 121.2 130.7 192.8

Estimate ΔG°_rxn for the following reaction at 449.0 K. CH₂O(g) + 2 H₂(g) → CH₄(g) + H₂O(g) ΔH° = -94.9 kJ;ΔS° = -224.2 J/K

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

Calculate ?S°_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

Place the following in order of decreasing molar entropy at 298 K. H₂ Cl₂ F₂

Place the following in order of increasing molar entropy at 298 K. CO₂ C₃H₈ SO

Estimate ΔG°_rxn for the following reaction at 775 K. 2 Hg(g) + O₂(g) → 2 HgO(s) ΔH° = -304.2 kJ;ΔS° = -414.2 J/K

Calculate ΔS°_rxn for the following reaction.The S°for each species is shown below the reaction. C₂H₂(g) + 2 H₂(g) → C₂H₆(g) S°(J/mol^∙K) 200.9 130.7 229.2