Given: H2O(l) F1F1F1S1F1F1F10 H2O(g) F1F1F1S1F1F1F10H° = 40.7 kJ at 373K What is the entropy change in the system (F1F1F1S1F1F1F10S) when one mole of water vaporizes at 100 °C and a pressure of one atmosphere?

A) 407 J/K B) -407 J/K C) 109 J/K D) -109 J/K E) J/K A) 407 J/K B) -407 J/K C) 109 J/K D) -109 J/K E) J/K C

Which relationship best describes F1F1F1S1F1F1F10S° for the following reaction? CO(g) + H2O(g) F1F1F1S1F1F1F10 CO2(g) + H2(g)

A) .F1F1F1S1F1F1F10S° = F1F1F1S1F1F1F10H° B) .F1F1F1S1F1F1F10S° = F1F1F1S1F1F1F10H°/T C) .F1F1F1S1F1F1F10S° > 0 D) .F1F1F1S1F1F1F10S° F1F1F1S1F1F1F10 0 A) .F1F1F1S1F1F1F10S° = F1F1F1S1F1F1F10H° B) .F1F1F1S1F1F1F10S° = F1F1F1S1F1F1F10H°/T C) .F1F1F1S1F1F1F10S° > 0 D) .F1F1F1S1F1F1F10S° F1F1F1S1F1F1F10 0

Calculate F1F1F1S1F1F1F10S° for the reaction

A) -118.2 J/K B) -104.8 J/K C) 104.8 J/K D) 118.2 J/K E) 1270.0 J/K A) -118.2 J/K B) -104.8 J/K C) 104.8 J/K D) 118.2 J/K E) 1270.0 J/K

Calculate F1F1F1S1F1F1F10S° for the reaction

A) -254.96 J/K B) -198.02 J/K C) 198.02 J/K D) 254.96 J/K E) 471.86 J/K A) -254.96 J/K B) -198.02 J/K C) 198.02 J/K D) 254.96 J/K E) 471.86 J/K

Calculate F1F1F1S1F1F1F10G° for the reaction of ammonia with fluorine.

A) 179.1 kJ B) -179.1 kJ C) 1539.7 kJ D) -1539.7 kJ E) none of the above A) 179.1 kJ B) -179.1 kJ C) 1539.7 kJ D) -1539.7 kJ E) none of the above

You are given pure samples of ethane, C2H6(g), and toluene, C7H8(l). What prediction would you make concerning their standard molar entropies at 298 K?

A) S°ethane > S°toluene B) S°ethane toluene C) S°ethane F1F1F1S1F1F1F10 (S°toluene) ÷ 3 D) S°ethane F1F1F1S1F1F1F10 S°toluene E) Since toluene is much more complex than ethane, but ethane is in the gas phase while toluene is a liquid, none of the above predictions can be confidently made without further information or calculations. A) S°ethane > S°toluene B) S°ethane toluene C) S°ethane F1F1F1S1F1F1F10 (S°toluene) ÷ 3 D) S°ethane F1F1F1S1F1F1F10 S°toluene E) Since toluene is much more complex than ethane, but ethane is in the gas phase while toluene is a liquid, none of the above predictions can be confidently made without further information or calculations.

A certain process has F1F1F1S1F1F1F10H° > 0, F1F1F1S1F1F1F10S° 0. The values of F1F1F1S1F1F1F10H° and F1F1F1S1F1F1F10S° do not depend on the temperature. Which of the following is a correct conclusion about this process?

A) It is non-spontaneous at all T. B) It is spontaneous at high T. C) It is spontaneous at low T. D) It is spontaneous at all T. E) None of the above conclusions is correct. A) It is non-spontaneous at all T. B) It is spontaneous at high T. C) It is spontaneous at low T. D) It is spontaneous at all T. E) None of the above conclusions is correct.

The formation constant for the reaction Is Kf = 1.7 × 107 at 25°C. What is F1F1F1S1F1F1F10G° at this temperature?

A) -1.5 kJ B) -3.5 kJ C) -18 kJ D) -23 kJ E) -41 kJ A) -1.5 kJ B) -3.5 kJ C) -18 kJ D) -23 kJ E) -41 kJ

Exam 20: Thermodynamics: Entropy, Free Energy, and the Direction of Chemical Reactions

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Given: H₂O(l)  H₂O(g) H° = 40.7 kJ at 373K What is the entropy change in the system (S) when one mole of water vaporizes at 100 °C and a pressure of one atmosphere?

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a. Explain what is meant by a spontaneous process. b. Is a spontaneous process necessarily a rapid one? Explain, and provide a real reaction as an example to illustrate your answer.

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a. A spontaneous process is one which will occur naturally, given enough time.
b. No, a spontaneous process may be immeasurably slow. An example is the conversion of diamond to graphite at room temperature and one atmosphere.

Elemental boron can be formed by reaction of boron trichloride with hydrogen.

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Which relationship best describes S° for the following reaction? CO(g) + H₂O(g)  CO₂(g) + H₂(g)

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Question 4

Compare one mole of ice with one mole of liquid water, both at 1.0 atm and 0°C. The melting point of ice at 1.0 atm is 0°C. For the process H₂O(s)  H₂O(l) under these conditions predict whether each of the following quantities will be greater than, less than, or equal to, zero . Explain each prediction in one sentence. a. H° b. S° c. G°

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Question 5

Iron(III) oxide can be reduced by carbon monoxide. Use the following thermodynamic data at 298 K to determine the equilibrium constant at this temperature.

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Question 6

Consider the figure which shows G° for a chemical process plotted against absolute temperature. Which one of the following is an incorrect conclusion, based on the information in the diagram?

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Question 7

For a given reaction, a change in the pressure may result in a change in the sign of G.

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Question 8

Which one of the following changes of state increases the entropy of the system?

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Question 9

State the second and third laws of thermodynamics.

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Question 10

A chemical reaction has H° = 42.8 kJ and S° = 92.5 J/K, at 25°C. Calculate the temperature at which G° = 0. State any approximation involved in your calculation.

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Question 11

For a chemical reaction to be spontaneous only at high temperatures, which of the following conditions must be met?

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Question 12

Calculate S° for the reaction

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Question 13

Calculate S° for the reaction

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Question 14

Calculate G°for the reaction of ammonia with fluorine.

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Question 15

For a chemical reaction to be spontaneous only at low temperatures, which of the following conditions must be met?

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Question 16

You are given pure samples of ethane, C₂H₆(g), and toluene, C₇H₈(l). What prediction would you make concerning their standard molar entropies at 298 K?

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Question 17

For each of the following pairs, predict which (A or B) will have the greater entropy, and in one sentence indicate your reasoning.

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Question 18

A certain process has H° > 0, S° < 0, and G° > 0. The values of H° and S° do not depend on the temperature. Which of the following is a correct conclusion about this process?

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Question 19

The formation constant for the reaction Is K_f = 1.7 × 10⁷ at 25°C. What is G°at this temperature?

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Question 20

Showing 1 - 20 of 94

Exam 20: Thermodynamics: Entropy, Free Energy, and the Direction of Chemical Reactions

Given: H2O(l)  H2O(g) H° = 40.7 kJ at 373K What is the entropy change in the system (S) when one mole of water vaporizes at 100 °C and a pressure of one atmosphere?

a. Explain what is meant by a spontaneous process. b. Is a spontaneous process necessarily a rapid one? Explain, and provide a real reaction as an example to illustrate your answer.

Elemental boron can be formed by reaction of boron trichloride with hydrogen.

Which relationship best describes S° for the following reaction? CO(g) + H2O(g)  CO2(g) + H2(g)

Iron(III) oxide can be reduced by carbon monoxide. Use the following thermodynamic data at 298 K to determine the equilibrium constant at this temperature.

Consider the figure which shows G° for a chemical process plotted against absolute temperature. Which one of the following is an incorrect conclusion, based on the information in the diagram?

For a given reaction, a change in the pressure may result in a change in the sign of G.

Which one of the following changes of state increases the entropy of the system?

State the second and third laws of thermodynamics.

A chemical reaction has H° = 42.8 kJ and S° = 92.5 J/K, at 25°C. Calculate the temperature at which G° = 0. State any approximation involved in your calculation.

For a chemical reaction to be spontaneous only at high temperatures, which of the following conditions must be met?

Calculate S° for the reaction

Calculate S° for the reaction

Calculate G° for the reaction of ammonia with fluorine.

For a chemical reaction to be spontaneous only at low temperatures, which of the following conditions must be met?

You are given pure samples of ethane, C2H6(g), and toluene, C7H8(l). What prediction would you make concerning their standard molar entropies at 298 K?

For each of the following pairs, predict which (A or B) will have the greater entropy, and in one sentence indicate your reasoning.

A certain process has H° > 0, S° < 0, and G° > 0. The values of H° and S° do not depend on the temperature. Which of the following is a correct conclusion about this process?

The formation constant for the reaction Is Kf = 1.7 × 107 at 25°C. What is G° at this temperature?

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Given: H₂O(l)  H₂O(g) H° = 40.7 kJ at 373K What is the entropy change in the system (S) when one mole of water vaporizes at 100 °C and a pressure of one atmosphere?

Which relationship best describes S° for the following reaction? CO(g) + H₂O(g)  CO₂(g) + H₂(g)

Calculate G°for the reaction of ammonia with fluorine.

You are given pure samples of ethane, C₂H₆(g), and toluene, C₇H₈(l). What prediction would you make concerning their standard molar entropies at 298 K?

The formation constant for the reaction Is K_f = 1.7 × 10⁷ at 25°C. What is G°at this temperature?