Deck 14: Entropy and Gibbs Energy

Question 1

The following substances are ordered with increasing entropy: neon gas < liquid water < a gold bar.

Answer 1

False

Question 2

The entropy change for the following reaction will be negative:
C₁₁H₂₂O₁₁ (s) + 12 O₂ (g) → 12 CO₂ (g) + 11 H₂O (l)

Answer 2

False

Question 3

The entropy change for the following reaction will be positive:
N₂ (g) + 3 H₂ (g) → 2 NH₃ (g)

Answer 3

False

Question 4

Entropy is identified with the amount of ________ in the system.

Question 5

Calculate the entropy change ( , J K^-1 mol^-1) when 1.00 mol of ethanol at its boiling point (T_b =78.45 °C) vaporizes (in the process the temperature does not change, for ethanol is + 43.5 kJ mol^-1).

A) + 124.
B) - 124.
C) + 554.
D) + 0.12.

Question 6

Calculate the entropy change ( , J K^-1 mol^-1) when 1.00 mol of mercury at its boiling point (T_b = 356.55 °C) vaporizes (in the process the temperature does not change, for mercury is + 59.3 kJ mol^-1).

A) - 94.
B) + 94.
C) + 166.
D) + 0.09.

Question 7

Calculate the entropy change ( , J K^-1 mol^-1) when 1.00 mol of methane at its melting point (T_m = - 182.05 °C) freezes (in the process the temperature does not change and for methane is + 0.94 kJ mol^-1).

A) - 10.3.
B) - 0.01.
C) + 10.3.
D) - 5.2.

Question 8

For water = + 109 J K^-1 mol^-1 whilst = + 22 J K^-1 mol^-1. The entropy change for vaporization is larger than the entropy change for fusion because it is measured at a higher temperature.

Question 9

Whether the total entropy change (ΔS_(total)) of a process is positive, negative, or equal to zero defines whether the process is spontaneous. Match the (ΔS_(total)) condition with its description.
-ΔS_(total) > 0

A) spontaneous process
B) non-spontaneous process
C) process at equilibrium

Question 10

Whether the total entropy change (ΔS_(total)) of a process is positive, negative, or equal to zero defines whether the process is spontaneous. Match the (ΔS_(total)) condition with its description.
-ΔS_(total) < 0

A) spontaneous process
B) non-spontaneous process
C) process at equilibrium

Question 11

Whether the total entropy change (ΔS_(total)) of a process is positive, negative, or equal to zero defines whether the process is spontaneous. Match the (ΔS_(total)) condition with its description.
-ΔS_(total) = 0

A) spontaneous process
B) non-spontaneous process
C) process at equilibrium

Question 12

Calculate the change of entropy (in J K^-1 mol^-1) when 1 mol of methanol is heated at constant pressure from 5 °C to 35 °C, the molar heat capacity, C_p, of methanol is 81.6 J K^-1 mol^-1, assume that the molar heat capacity, C_p is constant over this temperature range.

A) + 8.36.
B) - 8.36.
C) - 158.79.
D) + 158.79.

Question 13

Calculate the change of entropy (in J K^-1 mol^-1) when 1 mol of ethanol is cooled at constant pressure from 25 °C to 10 °C, the molar heat capacity, C_p, of ethanol is 111.5 J K^-1 mol^-1 and assume that C_p is constant over this temperature range.

A) + 5.8.
B) - 5.8.
C) - 102.2.
D) + 102.2.

Question 14

When 1 mol of trichloromethane is heated from 5 °C to 20 °C at constant pressure, the change of entropy is + 6.00 J K^-1 mol^-1. When the solvent is heated further from 20 °C to 35 °C, the change in entropy will also be + 6.00 J K^-1 mol^-1.

Question 15

When 1 mol of water is heated from 10 °C to 25 °C at constant pressure, the change in entropy is + 3.89 J K^-1 mol^-1. When 1 mol of methanol is heated from 10 °C to 25 °C at constant pressure, the change in entropy will be smaller.

Question 16

At zero kelvin the entropy of a perfect crystal is ____.

Question 17

Calculate the standard entropy of 1 mol of water at 20 °C and 1 bar. The molar heat capacity, C_p, of water is 75.3 J K^-1 mol^-1 and is 69.9 J K^-1 mol^-1.

A) 69.9.
B) - 133.5.
C) 68.7.
D) 71.1.

Question 18

The standard entropy of ethanol, at 1 bar, is 159.9 J K^-1 mol^-1. At 315 K, its standard entropy will be larger.

Question 19

The standard entropy change for the following reaction will be large and positive. CS₂ (l) + 3O₂ (g) → CO₂ (g) + 2SO₂ (g)

Question 20

Using data in Appendix 7, (p. 1350), calculate the standard entropy change of reaction ( in J K^-1 mol^-1) for the following reaction: CH₄ (g) + 2 O₂ (g) → CO₂ (g) + 2 H₂O (l)

A) + 243.0.
B) - 243.0.
C) - 107.8.
D) + 107.8.

Question 21

Using data in Appendix 7, (p. 1350), calculate the standard entropy change of reaction (in J K^-1 mol^-1) for the following reaction:
NH₃ (g) + HNO₃ (l) → NH₄NO₃ (s)

A) - 197.
B) + 197.
C) -151.1.
D) +151.1.

Question 22

The standard entropy change, for the following reaction is: -198.7 J K^-1 mol^-1.
N₂ (g) + 3 H₂ (g) → 2 NH₃ (g) Calculate the standard entropy change of reaction (in J K^-1 mol^-1) at 550 K.

A) - 226.
B) - 171.
C) + 226.
D) + 171.

Question 23

The standard entropy change, for the following reaction is: + 511.9 J K^-1 mol^-1.
C₁₂H₂₂O₁₁ (s) + 12 O₂ (g) → 12 CO₂ (g) + 11 H₂O (l) Calculate the standard entropy change of reaction (in J K^-1 mol^-1) at 390 116.85 °C.

A) + 511.9.
B) + 48.3.
C) + 379.
D) + 645.

Question 24

The standard entropy change, is: - 198.7 J K^-1 mol^-1, for the following reaction: N₂ (g) + 3 H₂ (g) → 2 NH₃ (g) This violates the Second Law of thermodynamics.

Question 25

Whether Gibbs energy change (ΔG) of a process is positive, negative, or equal to zero defines whether the process is spontaneous. Match the situation with its description.
-ΔG < 0

A) the reaction or process is spontaneous
B) the reaction or process is non-spontaneous
C) the reaction or process is at equilibrium

Question 26

Whether Gibbs energy change (ΔG) of a process is positive, negative, or equal to zero defines whether the process is spontaneous. Match the situation with its description.
-ΔG > 0

A) the reaction or process is spontaneous
B) the reaction or process is non-spontaneous
C) the reaction or process is at equilibrium

Question 27

Whether Gibbs energy change (ΔG) of a process is positive, negative, or equal to zero defines whether the process is spontaneous. Match the situation with its description.
-ΔG = 0

A) the reaction or process is spontaneous
B) the reaction or process is non-spontaneous
C) the reaction or process is at equilibrium

Question 28

Match the reaction description and whether it is spontaneous and under which conditions
-ΔH > 0, ΔS < 0

A) Never spontaneous
B) Spontaneous on heating
C) Always spontaneous
D) Spontaneous on cooling

Question 29

Match the reaction description and whether it is spontaneous and under which conditions
-ΔH > 0, ΔS > 0

A) Never spontaneous
B) Spontaneous on heating
C) Always spontaneous
D) Spontaneous on cooling

Question 30

Match the reaction description and whether it is spontaneous and under which conditions
-ΔH < 0, ΔS > 0

A) Never spontaneous
B) Spontaneous on heating
C) Always spontaneous
D) Spontaneous on cooling

Question 31

Match the reaction description and whether it is spontaneous and under which conditions
-ΔH < 0, ΔS < 0

A) Never spontaneous
B) Spontaneous on heating
C) Always spontaneous
D) Spontaneous on cooling

Question 32

An endothermic reaction has , and . Find the temperature, T(K), at which the reaction becomes spontaneous.

A) 298.
B) 783.
C) 0.78.
D) 1.28.

Question 33

Using and data given below:

Calculate the standard Gibbs energy change, (kJ mol^-1), for the following reaction:
2 NH₃ (g) → N₂ (g) + 3 H₂ (g)

A) + 151.
B) - 151.
C) + 33.
D) - 59.

Question 34

Using and data given below:
Calculate the standard Gibbs energy change, (kJ mol^-1), for the following reaction:
CH₄ (g) + 2 O₂ (g) → CO₂ (g) + 2 H₂O (l)

A) - 818.
B) + 71.5.
C) + 963.
D) - 963.

Question 35

Using data given below:

Calculate the standard Gibbs energy change, (kJ mol^-1), for the following reaction:
CO (g) + 2 H₂ (g) → CH₃OH (g)

A) - 299.2.
B) + 299.2.
C) + 24.8.
D) - 24.8.

Question 36

Using data given below:
calculate the standard Gibbs energy change, (kJ mol^-1), for the following reaction:
CO₂ (g) + CH₄ (g) → CH₃CO₂H (l)

A) - 835.1
B) - 55.3.
C) + 835.1.
D) + 55.3.

Question 37

Using data given below:

Calculate the standard Gibbs energy change, (kJ mol^-1), for the following reaction:
C₁₂H₂₂O₁₁ (s) + 12 O₂ (g) → 12 CO₂ (g) + 11 H₂O (l)

A) + 911.5.
B) - 5797.9.
C) + 5797.9.
D) - 911.5.

Question 38

An endothermic reaction with a positive entropy change will become spontaneous on cooling.

Question 39

Using the data given below estimate the value of the Gibbs energy change of reaction (kJ mol^-1) at 310 K, for the following reaction:
CH₃CH₂OH (l) + O₂ (g) → CH₃CO₂H (l) + H₂O (l)

A) - 450.2
B) - 451.8.
C) -41.7.
D) -533.8.

Question 40

Using the data given below estimate the value of the Gibbs energy change of reaction at 325 K, for the following reaction:
N₂ (g) + 2 O₂ (g) → 2 NO₂ (g)

A) + 26.1.
B) + 105.9.
C) + 102.6.
D) + 40.