Chapter 16- chemical thermodynamics

Question 1

Question

The first law of thermodynamics can be given as __________.

Answer

A) ΔE = q + w
B)

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c15d51cb-9887-4df0-8244-205bfe50fa15 (image/png)
C) for any spontaneous process, the entropy of the universe increases
D) the entropy of a pure crystalline substance at absolute zero is zero
E) ΔS = qrev/T at constant temperature

Question 2

Question

Of the following, only __________ is not a state function.

Answer

A) S
B) H
C) q
D) E
E) T

Question 3

Question

When a system is at equilibrium, __________.

Answer

A) the reverse process is spontaneous but the forward process is not
B) the forward and the reverse processes are both spontaneous
C) the forward process is spontaneous but the reverse process is not
D) the process is not spontaneous in either direction
E) both forward and reverse processes have stopped

Question 4

Question

A reversible process is one that __________.

Answer

A) can be reversed with no net change in either system or surroundings
B) happens spontaneously
C) is spontaneous in both directions
D) must be carried out at low temperature
E) must be carried out at high temperature

Question 5

Question

Which of the following statements is true?

Answer

A) Processes that are spontaneous in one direction are spontaneous in the opposite direction.
B) Processes are spontaneous because they occur at an observable rate.
C) Spontaneity can depend on the temperature.
D) All of the statements are true.

Question 6

Question

For an isothermal process, ΔS = __________.

Answer

A) q
B) qrev/T
C) qrev
D) Tqrev
E) q + w

Question 7

Question

Which one of the following is always positive when a spontaneous process occurs?

Answer

A) ΔSsystem
B) ΔSsurroundings
C) ΔSuniverse
D) ΔHuniverse
E) ΔHsurroundings

Question 8

Question

The second law of thermodynamics states that __________.

Answer

A) ΔE = q + w
B)

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40aeb3a4-6df7-4afb-b16b-91d0d14bda17 (image/png)
C) for any spontaneous process, the entropy of the universe increases
D) the entropy of a pure crystalline substance is zero at absolute zero
E) ΔS = qrev/T at constant temperature

Question 9

Question

Which of the following statements is false?

Answer

A) The change in entropy in a system depends on the initial and final states of the system and the path taken from one state to the other.
B) Any irreversible process results in an overall increase in entropy.
C) The total entropy of the universe increases in any spontaneous process.
D) Entropy increases with the number of microstates of the system.

Question 10

Question

Which one of the following processes produces a decrease of the entropy of the system?

Answer

A) dissolving sodium chloride in water
B) sublimation of naphthalene
C) dissolving oxygen in water
D) boiling of alcohol
E) explosion of nitroglycerine

Question 11

Question

Consider a pure crystalline solid that is heated from absolute zero to a temperature above the boiling point of the liquid. Which of the following processes produces the greatest increase in the entropy of the substance?

Answer

A) melting the solid
B) heating the liquid
C) heating the gas
D) heating the solid
E) vaporizing the liquid

Question 12

Question

Which one of the following correctly indicates the relationship between the entropy of a system and the number of different arrangements, W, in the system?

Answer

A) S = kW
B) S = k/W
C) S = W/k
D) S = klnW
E) S = Wk

Question 13

Question

ΔS is positive for the reaction __________.

Answer

A) 2H2 (g) + O2 (g) → 2H2O (g)
B) 2NO2 (g) → N2O4 (g)
C) CO2 (g) → CO2 (s)
D) BaF2 (s) → Ba2+ (aq) + 2F- (aq)
E) 2Hg (l) + O2 (g) → 2HgO (s)

Question 14

Question

Which reaction produces an increase in the entropy of the system?

Answer

A) Ag+ (aq) + Cl- (aq) → AgCl (s)
B) CO2 (s) → CO2 (g)
C) H2 (g) + Cl2 (g) → 2HCl (g)
D) N2 (g) + 3H2 (g) → 2NH3 (g)
E) H2O (l) → H2O (s)

Question 15

Question

Of the following, the entropy of __________ is the largest.

Answer

A) HCl (l)
B) HCl (s)
C) HCl (g)
D) HBr (g)
E) HI (g)

Question 16

Question

Of the following, the entropy of gaseous __________ is the largest at 25°C and 1 atm.

Answer

A) CH3OH
B) C2H5OH
C) C3H7OH
D) CH4
E) C4H10

Question 17

Question

For an isothermal process, the entropy change of the surroundings is given by the equation:

Answer

A) ΔS = qsys T
B) ΔS = -qsys T
C) ΔS = q lnT
D) ΔS = -q lnT
E) ΔS = -qsys/T

Question 18

Question

The equilibrium position corresponds to which letter on the graph of G vs. f (course of reaction) below?

Image:

081d1f25-ee4d-4896-9d67-3d2a475d85e2 (image/png)

Answer

A) A
B) B
C) C
D) D
E) E

Question 19

Question

For the reaction C2H6 (g) → C2H4 (g) + H2 (g) ΔH° is + 137 kJ/mol and ΔS° is +120 J/K ∙ mol. This reaction is __________.

Answer

A) spontaneous at all temperatures
B) spontaneous only at high temperature
C) spontaneous only at low temperature
D) nonspontaneous at all temperatures

Question 20

Question

For the reaction 2C4H10 (g) + 13O2 (g) → 8CO2 (g) + 10H2O (g) ΔH° is -125 kJ/mol and ΔS° is +253 J/K ∙ mol. This reaction is __________.

Answer

A) spontaneous at all temperatures
B) spontaneous only at high temperature
C) spontaneous only at low temperature
D) nonspontaneous at all temperatures
E) unable to determine without more information

Question 21

Question

A reaction that is not spontaneous at low temperature can become spontaneous at high temperature if ΔH is __________ and ΔS is __________.

Answer

A) +, +
B) -, -
C) +, -
D) -, +
E) +, 0

Question 22

Question

Given the following table of thermodynamic data, complete the following sentence. The vaporization of PCl3 (l) is __________.

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8f72d5a6-9845-4c4c-92a5-5bba6352ab7f (image/png)

Answer

A) nonspontaneous at low temperature and spontaneous at high temperature
B) spontaneous at low temperature and nonspontaneous at high temperature
C) spontaneous at all temperatures
D) nonspontaneous at all temperatures
E) not enough information given to draw a conclusion

Question 23

Question

Consider the reaction: Ag+ (aq) + Cl- (aq) → AgCl (s) Given the following table of thermodynamic data, determine the temperature (in °C) above which the reaction is nonspontaneous under standard conditions.

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eff02e7c-5edc-4c48-b431-0c186622fc8a (image/png)

Answer

A) 1230 °C
B) 150 °C
C) 432 °C
D) 133 °C
E) 1640 °C

Question 24

Question

Consider the reaction: NH3 (g) + HCl (g) → NH4Cl (s) Given the following table of thermodynamic data, determine the temperature (in °C) above which the reaction is nonspontaneous.

Answer

A) This reaction is spontaneous at all temperatures.
B) 618.1
C) 432.8
D) 345.0
E) 1235

Question 25

Question

With thermodynamics, one cannot determine __________.

Answer

A) the speed of a reaction
B) the direction of a spontaneous reaction
C) the extent of a reaction
D) the value of the equilibrium constant
E) the temperature at which a reaction will be spontaneous

Question 26

Question

If ΔG° for a reaction is greater than zero, then __________.

Answer

A) K = 0
B) K = 1
C) K > 1
D) K < 1
E) More information is needed.

Question 27

Question

The value of ΔS° for the catalytic hydrogenation of ethene to ethane, C2H4 (g) + H2(g) → C2H6 (g) is __________ J/K∙ mol.

Image:

8a1428c8-35d8-4dc9-8287-c31053343b59 (image/png)

Answer

A) -101.9
B) -120.5
C) -232.5
D) +112.0
E) +101.9

Question 28

Question

The value of ΔS° for the oxidation of carbon to carbon dioxide, C (s, graphite) + O2 (g) → CO2(g) is __________ J/K∙ mol. The combustion of carbon, as in charcoal briquettes, in the presence of abundant oxygen produces carbon dioxide.

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cf3170af-2265-4b00-8f99-b22b8c7bd237 (image/png)

Answer

A) +424.3
B) +205.0
C) -205.0
D) -2.9
E) +2.9

Question 29

Question

The value of ΔH° for the decomposition of gaseous sulfur trioxide to its component elements, 2SO3 (g) → 2S (s, rhombic) + 3O2 (g) is __________ kJ/mol.

Image:

1019f3e5-baa1-44a3-81a5-08e2cb075c54 (image/png)

Answer

A) +790.4
B) -790.4
C) +395.2
D) -395.2
E) +105.1

Question 30

Question

The value of ΔG° at 25 °C for the oxidation of solid elemental sulfur to gaseous sulfur trioxide, 2S (s, rhombic) + 3O2 (g) → 2SO3 (g) is __________ kJ/mol.

Answer

A) +740.8
B) -370.4
C) +370.4
D) -740.8
E) +185.2

Question 31

Question

Given the thermodynamic data in the table below, calculate the equilibrium constant (at 298 K) for the reaction: 2SO2 (g) + O2 (g) --> 2SO3 (g)

Image:

78e4d38c-0464-44e6-b6e2-89932ec70716 (image/png)

Answer

A) 2.37 × 1024
B) 1.06
C) 1.95
D) 3.82 × 1023
E) More data are needed.

Question 32

Question

The value of ΔG° for a reaction conducted at 25°C is 3.05 kJ/mol. The equilibrium constant for a reaction is __________ at this temperature?

Answer

A) 0.292
B) -4.20
C) 0.320
D) -1.13
E) More information is needed.

Question 33

Question

The normal boiling point of water is 100.0°C and its molar enthalpy of vaporization is 40.67 kJ/mol. What is the change in entropy in the system in J/K when 39.3 grams of steam at 1 atm condenses to a liquid at the normal boiling point?

Answer

A) 88.8
B) -88.8
C) -238
D) 373
E) -40.7

Question 34

Question

The standard Gibbs free energy of formation of __________ is zero. (a) H2O (l) (b) O (g) (c) I2 (s)

Answer

A) (a) only
B) (b) only
C) (c) only
D) (b) and (c)
E) (a), (b), and (c)

Question 35

Question

The standard Gibbs free energy of formation of __________ is zero. (a) H2O (l) (b) Mg (s) (c) Br2 (l)

Answer

A) (a) only
B) (b) only
C) (c) only
D) (b) and (c)
E) (a), (b), and (c)

Question 36

Question

The standard Gibbs free energy of formation of __________ is zero. (a) Si (s) (b) F2 (g) (c) Ni (s)

Answer

A) (a) only
B) (b) only
C) (c) only
D) (b) and (c)
E) (a), (b), and (c)

Question 37

Question

The value of ΔG° at 141.0°C for the formation of phosphorous trichloride from its constituent elements, P2 (g) + 3Cl2 (g) → 2PCl3 (g) is __________ kJ/mol. At 25.0°C for this reaction, ΔH° is -720.5 kJ/mol, ΔG° is -642.9 kJ/mol, and ΔS° is -263.7 J/K.

Answer

A) -612.3
B) 3.65 × 104
C) 1.08 × 105
D) -683.3
E) -829.7

Question 38

Question

For the reaction C(s) + H2O(g) → CO(g) + H2(g) ΔH° = 131.3 kJ/mol and ΔS° = 127.6 J/K ∙ mol at 298 K. At temperatures greater than __________°C this reaction is spontaneous under standard conditions.

Answer

A) 273
B) 325
C) 552
D) 756
E) 1029

Question 39

Question

For a given reaction, ΔH = +35.5 kJ/mol and ΔS = +83.6 J/K-mol. The reaction is spontaneous __________. Assume that ΔH and ΔS do not vary with temperature.

Answer

A) at T < 425 K
B) at T > 425 K
C) at all temperatures
D) at T > 298 K
E) at T < 298 K

Question 40

Question

In the Haber process, ammonia is synthesized from nitrogen and hydrogen: N2 (g) + 3H2 (g) → 2NH3 (g) ΔG° at 298 K for this reaction is -33.3 kJ/mol. The value of ΔG at 298 K for a reaction mixture that consists of 1.9 atm N2, 1.6 atm H2, and 0.65 atm NH3 is __________.

Answer

A) -1.8
B) -3.86 × 103
C) -7.25 × 103
D) -104.5
E) -40.5

Question 41

Question

Phosphorous and chlorine gases combine to produce phosphorous trichloride: P2 (g) + 3Cl2 (g) → 2PCl3 (g) ΔG° at 298 K for this reaction is -642.9 kJ/mol. The value of ΔG at 298 K for a reaction mixture that consists of 1.5 atm P2, 1.6 atm Cl2, and 0.65 atm PCl3 is __________.

Answer

A) -44.2
B) -3.88 × 103
C) -7.28 × 103
D) -708.4
E) -649.5

Question 42

Question

15) The equilibrium constant for a reaction is 0.35 at 25°C. What is the value of ΔG° (kJ/mol) at this temperature?

Answer

A) 2.6
B) -4.2
C) 220
D) 4.2
E) More information is needed.

Question 43

Question

A reversible change produces the maximum amount of ________ that can be achieved by the system on the surroundings.

Answer

A) Energy
B) Product
C) Reactant
D) Work

Question 44

Question

The melting of a substance at its melting point is an isothermal process.

Answer

True
False

Question 45

Question

The vaporization of a substance at its boiling point is an isothermal process

Answer

True
False

Question 46

Question

The entropy of a pure crystalline substance at 0°C is zero.

Answer

True
False

Question 47

Question

The more negative ΔG° is for a given reaction, the larger the value of the corresponding equilibrium constant, K.

Answer

True
False

	Created by Dawn G over 7 years ago

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Chapter 16- chemical thermodynamics

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