Chapter 19 Review Questions PDF

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Chapter 19 Review Questions...

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Chapter 19 Review Questions

1R) The first law of thermodynamics can be given as ________. A) ΔE = q + w B) Δ

=

-

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

Answer: A

2R) A reaction that is spontaneous as written

________. A) is very rapid B) will proceed without outside intervention C) is also spontaneous in the reverse direction D) has an equilibrium position that lies far to the left E) is very slow

Answer: B

3R) Of the following, only ________ is not a state function. A) S C) q E) T

B) H D) E Answer: C

4R) When a system is at equilibrium, ________. 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

Answer: D

5R) A reversible process is one that ________. 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

Answer: A

6R) Which of the following statements is true? 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.

Answer: C

7R) The thermodynamic quantity that expresses the extent of randomness in a system is ________. A) enthalpy C) bond energy E) heat flow

B) internal energy D) entropy Answer: D

8R) For an isothermal process, ΔS = ________. A) q

B) qrev/T

C) qrev

D) Tqrev

E) q + w

Answer: B

9R) Which one of the following is always positive when a spontaneous process occurs? A) ΔSsystem

B) ΔSsurroundings

C) ΔSuniverse E) ΔHsurroundings

D) ΔHuniverse Answer: C

10R) The entropy of the universe is ________. A) constant C) continually increasing E) the same as the energy, E

B) continually decreasing D) zero Answer: C

11R) The second law of thermodynamics states that ________. A) ΔE = q + w B) ΔH°rxn = Σ nΔH°f (products) - Σ mΔH°f (reactants) 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

Answer: C

12R) Which of the following statements is false? 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. Answer: A

13R) Which one of the following processes produces a decrease of the entropy of the system? A) dissolving sodium chloride in water C) dissolving oxygen in water E) explosion of nitroglycerine

B) sublimation of naphthalene D) boiling of alcohol Answer: C

14R) 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? A) melting the solid B) heating the liquid C) heating the gas D) heating the solid E) vaporizing the liquid Answer: E

15R) 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? A) S = kW

B) S =

C) S =

D) S = k lnW

E) S = Wk

Answer: D

17R) ΔS is positive for the reaction ________. 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)

Answer: D

20R) ΔS is positive for the reaction ________. A) 2 Ca (s) + O2 (g) → 2 CaO (s) B) 2 KClO3 (s) → 2KCl (s) + 3 O2 (g) C) HCl (g) + NH3 (g) → NH4Cl (s) D) Pb2+ (aq) + 2Cl- (aq) → PbCl2 (s) E) CO2 (g) → CO2 (s)

Answer: B

21R) Which reaction produces a decrease in the entropy of the system? A) CaCO3 (s) → CaO (s) + CO2 (g) B) 2C (s) + O2 (g) → 2CO (g) C) CO2 (s) → CO2 (g) D) 2H2 (g) + O2 (g) → 2H2O (l) E) H2O (l) → H2O (g)

Answer: D

23R) Which reaction produces an increase in the entropy of the system? A) Ag+ (aq) + Cl- (aq) → AgCl (s) B) CO2 (s) → CO2 (g) C) H2 (g) + Cl2 (g) → 2 HCl (g) D) N2 (g) + 3 H2 (g) → 2 NH3 (g) E) H2O (l) → H2O (s)

Answer: B

25R) ΔS is positive for the reaction ________. A) Pb(NO3)2 (aq) + 2KI(aq) → PbI2 (s) + 2KNO3 (aq) B) 2H2O (g) → 2H2 (g) + O2 (g) C) H2O (g) → H2O (s) D) NO (g) + O2 (g) → NO2 (g) E) Ag+ (aq) + Cl- (aq) → AgCl (s)

Answer: B

26R) For an isothermal process, the entropy change of the surroundings is given by the equation: A) ΔS = qsys T B) ΔS = -qsys T C) ΔS = q lnT D) ΔS = -q lnT E) ΔS = -qsys / T

Answer: E

27R) The equilibrium position corresponds to which letter on the graph of G vs. f (course of reaction) below?

A) A C) C E) E

B) B D) D Answer: C

28R) For the reaction C2H6 (g) → C2H4 (g) + H2 (g) ΔH° is +137 kJ/mol and ΔS° is +120 J/K ∙ mol. This reaction is ________. A) spontaneous at all temperatures B) spontaneous only at high temperature C) spontaneous only at low temperature D) nonspontaneous at all temperatures

Answer: B

30R) A reaction that is not spontaneous at low temperature can become spontaneous at high temperature if ΔH is ________ and ΔS is ________. A) +, + B) -, C) +, D) -, + E) +, 0

Answer: A

31R) Given the following table of thermodynamic data,

complete the following sentence. The vaporization of TiCl4 is ________. A) spontaneous at all temperatures B) spontaneous at low temperature and nonspontaneous at high temperature C) nonspontaneous at low temperature and spontaneous at high temperature D) nonspontaneous at all temperatures E) not enough information given to draw a conclusion

34R) Consider the reaction:

Answer: C

FeO (s) + Fe (s) + O2 (g) → Fe2O3 (s)

Given the thermodynamic data below, determine the temperature (in °C) above which the reaction is nonspontaneous.

Answer: 2438

36R) Which one of the following statements is true about the equilibrium constant for a reaction if ΔG° for the reaction is negative? A) K = 0 B) K = 1 C) K > 1 D) K < 1 E) More information is needed.

Answer: C

Use the table below to answer the questions that follow. Thermodynamic Quantities for Selected Substances at 298.15 K (25 °C) Substance

ΔH°f (kJ/mol) ΔG°f (kJ/mol) S (J/K-mol)

Carbon C (s, diamond) C (s, graphite) C2H2 (g) C2H4 (g) C2H6 (g) CO (g) CO2 (g) Hydrogen H2( g) Oxygen O2 (g) H2O (l)

1.88 0 226.7

2.84 0 209.2

2.43 5.69 200.8

52.30

68.11

219.4

-84.68

-32.89

229.5

-110.5 -393.5

0

-137.2 -394.4

197.9 213.6

0

130.58

0

0

205.0

-285.83

-237.13

69.91

1R) The value of ΔS° for the catalytic hydrogenation of acetylene to ethene is ________ J/K∙ mol. C2H2 (g) + H2 (g) → C2H4 (g) A) +18.6 B) +550.8 C) +112.0 D) -112.0 E) -18.6

Answer: D

2R) The combustion of acetylene in the presence of excess oxygen yields carbon dioxide and water: 2C2H2 (g) + 5O2 (g) → 4CO2 (g) + 2H2O (l) The value of ΔS° for this reaction is ________ J/K ∙ mol. A) +689.3 B) +122.3 C) +432.4 D) -122.3 E) -432.4

Answer: E

7R) The value of ΔS° & ΔH° & ΔG° 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.

Answer: 2.9, -393.5, -394.4

9R) The co mbustion of ethane in the presence of excess oxygen yields carbon dioxide and water: 2C2H6 (g) + 7O2 (g) → 4CO2 (g) + 6H2O (l) The value of ΔS° & ΔH° & ΔG° for this reaction is ________ J/K ∙ mol.

Answer: -620.1, -3121, -2936

42R) The value of ΔG° at 25 °C for the following reaction: C2H4 (g) + H2 (g) → C2H6 (g) is ________ kJ/mol. At 298 K, ΔH° for this reaction is -137.5 kJ/mol, and ΔS° is +120.5 J/K. A) -35800 B) -173.4 C) 35800 D) -101.7 E) -274.2

Answer: B

43R) Given the thermodynamic data in the table below, calculate the equilibrium constant (at 298 K) for the reaction: 2 SO2 (g) + O2 (g)

2 SO3 (g)

A) 2.40 × 1024 B) 1.06 C) 1.95 D) 3.82 × 1023 E) More data are needed.

Answer: A

46R) Consider the reaction: NH3 (g) + HCl (g) → NH4Cl (s) Given the following table of thermodynamic data at 298 K:

The value of K for the reaction at 25 °C is ________. A) 150 B) 9.3 × 1015 C) 8.4 × 104 E) 1.4 × 108

D) 1.1 × 10-16 Answer: B

2R) 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 24.7 grams of steam at 1 atm condenses to a liquid at the normal boiling point? A) 88.8 B) -88.8 C) -150 D) 373 E) -40.7 Answer: C

3R) The normal boiling point of C2Cl3F3 is 47.6 °C and its molar enthalpy of vaporization is 27.49 kJ/mol. What is the change in entropy in the system in J/K when 28.6 grams of C2Cl3F3 vaporizes to a gas at the normal boiling point? A) -13.1 C) 4.19 E) 27.5

B) -4.19 D) 13.1 Answer: D

4R) The normal boiling point of ethanol (C2H5OH) is 78.3 °C and its molar enthalpy of vaporization is 38.56 kJ/mol. What is the change in entropy in the system in J/K when 112.2 grams of ethanol at 1 atm condenses to a liquid at the normal boiling point? A) 382 B) 1199 C) -382 D) -1199 E) -267 Answer: E

6R) ΔS is negative for the reaction ________. A) Sr(NO3)2 (aq) + 2LiOH (aq) → Sr(OH)2 (s) + 2LiNO3 (aq) B) 2H2O (g) → 2H2 (g) + O2 (g) C) CH3OH (l) → CH3OH (g) D) LiOH (aq) → Li+ (aq) + OH– (aq) E) C6H12O6 (s) → 6C (s) + 6H2 (g) + 3O2 (g)

Answer: A

8R) Of the following, the entropy of ________ is the largest. A) B2F4 (g) C) B2H6 (g) E) B2O3 (s)

B) BF3 (g) D) BCl3 (l) Answer: A

10R) Of the following, the entropy of gaseous ________ is the largest at 25 °C and 1 atm. A) I2

B) F2

C) Cl2

D) Br2

E) O3

Answer: A

11R) The standard Gibbs free energy of formation of ________ is zero. (a) H2O (l)

(b) O (g)

(c) Cl2 (g)

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

Answer: C

12R) The standard Gibbs free energy of formation of ________ is zero. (a) H2O (l)

(b) Fe (s)

(c) I2 (s)

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

Answer: D

3R) Calculate ΔG∘ (in kJ/mol) for the following reaction at 1 atm and 25 °C: C2H6 (g) + O2 (g) → CO2 (g) + H2O (l) (unbalanced) ΔHf∘ C2H6 (g) = -84.7 kJ/mol; ΔHf∘ CO2 (g) = -393.5 kJ/mol;

S∘ C2H6 (g) = 229.5 J/K ∙ mol; S∘ CO2 (g) = 213.6 J/K ∙ mol;

ΔHf∘ H2O (l) = -285.8 kJ/mol;

S∘ H2O (l) = 69.9 J/K ∙ mol; S∘ O2 (g) = 205.0 J/K ∙ mol Answer: -2934.0

Diff: 5...