Deck 19: Chemical Thermodynamics

Question 1

The entropy change accompanying any process is given by the equation:

A)ΔS = k lnW_final
B)ΔS = k W_final - k W_initial
C)ΔS = k ln(W_final / W_initial)
D)ΔS = k _final - k _initial
E)ΔS = W_final - W_initial

Answer 1

ΔS = k ln(W_final / W_initial)

Question 2

For an isothermal process,ΔS = ________.

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

Answer 2

/T

Question 3

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

A)ΔS_system
B)ΔS_surroundings
C)ΔS_universe
D)ΔH_universe
E)ΔH_surroundings

Answer 3

ΔS_universe

Question 4

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 = q_rev/T at constant temperature

Question 5

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)

Question 6

ΔS is positive for the reaction ________.

A)2NO (g)+ O₂ (g)→ 2NO₂ (g)
B)2N₂ (g)+ 3H₂ (g)→ 2NH₃ (g)
C)C₃H₈ (g)+ 5 O₂ (g)→ 3CO₂ (g)+ 4 H₂O (g)
D)Mg (s)+ Cl₂ (g)→ MgCl₂ (s)
E)C2H₄ (g)+ H₂ (g)→ C₂H₆ (g)

Question 7

ΔS is positive for the reaction ________.

A)CaO (s)+ CO₂ (g)→ CaCO₃ (s)
B)N₂ (g)+ 3H₂ (g)→ 2NH₃ (g)
C)2SO₃ (g)→ 2SO₂ (g)+ O₂ (g)
D)Ag⁺ (aq)+ Cl^- (aq)→ AgCl (s)
E)H₂O (l)→ H₂O (s)

Question 8

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

Question 9

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

Question 10

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

Question 11

The thermodynamic quantity that expresses the extent of randomness in a system is ________.

A)enthalpy
B)internal energy
C)bond energy
D)entropy
E)heat flow

Question 12

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

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

Question 13

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

Question 14

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

Question 15

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 = /T at constant temperature

Question 16

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.

Question 17

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)

Question 18

The entropy of the universe is ________.

A)constant
B)continually decreasing
C)continually increasing
D)zero
E)the same as the energy, E

Question 19

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.

Question 20

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

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

Question 21

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.

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

Question 22

Consider the reaction: FeO (s)+ Fe (s)+ O₂ (g)→ Fe₂O₃ (s)
Given the following table of thermodynamic data, determine the temperature (in °C)at which the reaction is nonspontaneous.

A)below 618.1
B)above 2438
C)above 756.3
D)below 2438
E)This reaction is spontaneous at all temperatures.

Question 23

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.

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

Question 24

Given the following table of thermodynamic data, complete the following sentence.The vaporization of Ti 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

Question 25

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

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

Question 26

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)

Question 27

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.

Question 28

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)

Question 29

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)

Question 30

With thermodynamics,one cannot determine ________.

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 31

A reaction that is not spontaneous at low temperature can become spontaneous at high temperature if is ________ and is ________.

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

Question 32

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

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

Question 33

A decrease in the entropy of the system is observed for the reaction ________.

A)4 NH₃ (g)+ 5 O₂ (g)→ 4 NO (g)+ 6 H₂O (g)
B)2 HgO (s)→ 2 Hg (l)+ O₂ (g)
C)UF₆ (s)→ U (s)+ 3F₂ (g)
D)K (s)+ 1/2 I₂ (g)→ KI (s)
E)H₂O (s)→ H₂O (g)

Question 34

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

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

Question 35

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

Question 36

For the reaction 2 C₄H₁₀ (g)+ 13 O₂ (g)→ 8 CO₂ (g)+ 10 H₂O (g)
ΔH° is -125 kJ/mol and ΔS° is +253 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
E)unable to determine without more information

Question 37

The value of ΔS° for the reaction 2C (s,diamond)+ O₂ (g)→ 2CO (g)
Is ________ J/K ∙ mol.

A)-185.9
B)+185.9
C)-9.5
D)+9.5
E)-195.7

Question 38

Which of the following reactions would have a negative ΔS?

A)NH₄Cl (s)→ NH₃ (g)+ HCl (g)
B)PbCl₂ (s)→ Pb²⁺ (aq)+ 2Cl^- (aq)
C)2C (s)+ O₂ (g)→ 2CO₂ (g)
D)2SO₂ (g)+ O₂ (g)→ 2SO₃ (g)
E)H₂O (l)→ H₂O (g)

Question 39

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

Question 40

The value of ΔS° for the catalytic hydrogenation of acetylene to ethene, C₂H₂ (g)+ H₂ (g)→ C₂H₄ (g)
Is ________ J/K∙ mol.

A)+18.6
B)+550.8
C)+112.0
D)-112.0
E)-18.6

Question 41

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.

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

Question 42

The value of ΔH° for the oxidation of solid elemental sulfur to gaseous sulfur trioxide,
2S (s,rhombic)+ 3O₂( g)→ 2SO₃ (g)
Is ________ kJ/mol.

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

Question 43

The combustion 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° for this reaction is ________ J/K ∙ mol.

A)+718.0
B)-620.1
C)-718.0
D)-151.0
E)+151.0

Question 44

The value of ΔS° for the decomposition of calcium chloride into its constituent elements, CaCl₂ (s)→ Ca (s)+ Cl₂ (g)
Is ________ J/K ∙ mol.

A)-104.6
B)+104.6
C)+369.0
D)-159.8
E)+159.8

Question 45

The value of ΔS° for the catalytic hydrogenation of acetylene to ethane, C₂H₂ (g)+ 2H₂ (g)→ C₂H₆ (g)
Is ________ J/K ∙ mol.

A)-76.0
B)+440.9
C)-232.5
D)+232.5
E)+28.7

Question 46

The value of ΔS° for the formation of calcium chloride from its constituent elements, Ca (s)+ Cl₂ (g)→ CaCl₂ (s)
Is ________ J/K ∙ mol.

A)-104.6
B)+104.6
C)+369.0
D)-159.8
E)+159.8

Question 47

The value of ΔS° for the formation of phosphorous trichloride from its constituent elements, P₂ (g)+ 3Cl₂ (g)→ 2PCl₃ (g)
Is ________ J/K ∙ mol.

A)-311.7
B)+311.7
C)-263.6
D)+129.4
E)-129.4

Question 48

The value of ΔS° for the formation of POCl₃ from its constituent elements, P₂ (g)+ O₂ (g)+ 3Cl₂ (g)→ 2POCl₃ (g)
Is ________ J/K ∙ mol.

A)-442.0
B)+771.0
C)-321.0
D)-771.0
E)+321.0

Question 49

The combustion of hydrogen in the presence of excess oxygen yields liquid water: What is the value of ΔS° in J/K ∙ mol.for this reaction?

A)-405.5
B)+405.5
C)-265.7
D)-326.3
E)+265.7

Question 50

The combustion of ethene in the presence of excess oxygen yields carbon dioxide and water: C₂H₄ (g)+ 3O₂ (g)→ 2CO₂ (g)+ 2H₂O (l)
The value of ΔS° for this reaction is ________ J/K ∙ mol.

A)-267.4
B)-140.9
C)-347.6
D)+347.6
E)+140.9

Question 51

The value of ΔS° for the decomposition of gaseous sulfur trioxide to solid elemental sulfur and gaseous oxygen,
2SO₃ (g)→ 2S (s,rhombic)+ 3O₂ (g)
Is ________ J/K ∙ mol.

A)+19.3
B)-19.3
C)+493.1
D)+166.4
E)-493.1

Question 52

The value of ΔH° for the decomposition of gaseous sulfur dioxide to solid elemental sulfur and gaseous oxygen, SO₂ (g)→ S (s,rhombic)+ O₂ (g)
Is ________ kJ/mol.

A)0.0
B)+135.0
C)-135.90
D)-269.9
E)+269.9

Question 53

The value of ΔS° for the oxidation of carbon to carbon monoxide,
2C (s,graphite)+ O₂ (g)→ 2CO (g)
Is ________ J/K ∙ mol.Carbon monoxide is produced in the combustion of carbon with limited oxygen.

A)-12.8
B)+408.6
C)-408.6
D)+179.4
E)+395.8

Question 54

The value of ΔH° for the oxidation of solid elemental sulfur to gaseous sulfur dioxide,
S (s,rhombic)+ O₂ (g)→ SO₂ (g)
Is ________ kJ/mol.

A)+269.9
B)-269.9
C)+0.00
D)-11.6
E)+11.6

Question 55

The value of ΔS° for the decomposition of gaseous sulfur dioxide to solid elemental sulfur and gaseous oxygen,
SO₂ (g)→ S (s,rhombic)+ O₂ (g)
Is ________ J/K ∙ mol.

A)+485.4
B)+248.5
C)-11.6
D)-248.5
E)+11.6

Question 56

The value of ΔS° for the decomposition of POCl₃ into its constituent elements, 2POCl₃ (g)→ P₂ (g)+ O₂ (g)+ 3Cl₂ (g)
Is ________ J/K ∙ mol.

A)+771.0
B)+442.0
C)-321.0
D)-771.0
E)+321.0

Question 57

The value of ΔS° for the decomposition of phosphorous trichloride into its constituent elements, 2PCl₃ (g)→ P₂ (g)+ 3Cl₂( g)
Is ________ J/K ∙ mol.

A)-311.7
B)+311.7
C)+263.6
D)+129.4
E)-129.4

Question 58

The value of ΔS° for the oxidation of solid elemental sulfur to gaseous sulfur trioxide,
2S (s,rhombic)+ 3O₂(g)→ 2SO₃ (g)
Is ________ J/K ^∙ mol.

A)+19.3
B)-19.3
C)+493.1
D)-166.4
E)-493.1

Question 59

The value of ΔS° for the oxidation of solid elemental sulfur to gaseous sulfur dioxide,
S (s,rhombic)+ O₂(g)→ SO₂(g)
Is ________ J/K ∙ mol.

A)+485.4
B)+248.5
C)-11.6
D)-248.5
E)+11.6

Question 60

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.

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

Question 61

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

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

Question 62

The value of ΔH° for the decomposition of POCl₃ into its constituent elements, 2POCl₃ (g)→ P₂ (g)+ O₂ (g)+ 3Cl₂ (g)
Is ________ kJ/mol.

A)-1228.7
B)+1228.7
C)-940.1
D)+940.1
E)0.00

Question 63

The value of ΔG° at 25 °C for the formation of POCl₃ from its constituent elements, P₂ (g)+ O₂ (g)+ 3Cl₂ (g)→ 2POCl₃ (g)
Is ________ kJ/mol.

A)-1108.7
B)+1108.7
C)-606.2
D)+606.2
E)-1,005

Question 64

The value of ΔG° at 25 °C for the formation of phosphorous trichloride from its constituent elements, P₂ (g)+ 3Cl₂ (g)→ 2PCl₃ (g)
Is ________ kJ/mol.

A)-539.2
B)+539.2
C)-642.9
D)+642.9
E)-373.3

Question 65

The value of ΔH° for the decomposition of phosphorous trichloride into its constituent elements, 2PCl₃ (g)→ P₂ (g)+ 3Cl₂ (g)
Is ________ kJ/mol.

A)+576.2
B)-288.1
C)+720.5
D)+288.1
E)-720.5

Question 66

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.

Question 67

The value of ΔG° at 25 °C for the decomposition of POCl₃ into its constituent elements, 2POCl₃ (g)→ P₂ (g)+ O₂ (g)+ 3Cl₂ (g)
Is ________ kJ/mol.

A)-1108.7
B)+1108.7
C)-606.2
D)+606.2
E)-1,005

Question 68

The value of ΔG° at 25 °C for the decomposition of calcium chloride into its constituent elements, CaCl₂ (s)→ Ca (s)+ Cl₂ (g)
Is ________ kJ/mol.

A)-795.8
B)+795.8
C)+763.7
D)+748.1
E)-748.1

Question 69

The value of ΔH° for the formation of phosphorous trichloride from its constituent elements, P₂ (g)+ 3Cl₂ (g)→ 2PCl₃ (g)
Is ________ kJ/mol

A)-288.1
B)+432.4
C)-720.5
D)+720.5
E)-432.4

Question 70

The value of ΔG° at 25 °C for the decomposition of gaseous sulfur dioxide to solid elemental sulfur and gaseous oxygen, SO₂ (g)→ S (s,rhombic)+ O₂ (g)
Is ________ kJ/mol.

A)+395.2
B)+269.9
C)-269.9
D)+300.4
E)-300.4

Question 71

The value of ΔH° for the decomposition of calcium chloride into its constituent elements, CaCl₂ (s)→ Ca (s)+ Cl₂ (g)
Is ________ kJ/mol.

A)0.00
B)-397.9
C)+397.9
D)-795.8
E)+795.8

Question 72

The value of ΔG° at 25 °C for the formation of calcium chloride from its constituent elements, Ca (s)+ Cl₂ (g)→ CaCl₂ (s)
Is ________ kJ/mol.

A)-795.8
B)+795.8
C)+763.7
D)+748.1
E)-748.1

Question 73

The value of ΔG° at 373 K for the oxidation of solid elemental sulfur to gaseous sulfur dioxide is ________ kJ/mol.At 298 K,ΔH° for this reaction is -269.9 kJ/mol,and ΔS° is +11.6 J/K.

A)-300.4
B)-274.2
C)-4,597
D)+300.4
E)+4,597

Question 74

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.

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

Question 75

The value of ΔG° at 25 °C for the oxidation of solid elemental sulfur to gaseous sulfur dioxide, S (s,rhombic)+ O₂(g)→ SO₂ (g)
Is ________ kJ/mol.

A)+395.2
B)+269.9
C)-269.9
D)+300.4
E)-300.4

Question 76

The value of ΔG° at 25 °C for the decomposition of phosphorous trichloride into its constituent elements, 2PCl₃ (g)→ P₂ (g)+ 3Cl₂ (g)
Is ________ kJ/mol.

A)-539.2
B)+539.2
C)-642.9
D)+642.9
E)-373.3

Question 77

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.

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

Question 78

The value of ΔH° for the formation of calcium chloride from its constituent elements, Ca (s)+ Cl₂ (g)→ CaCl₂ (s)
Is ________ kJ/mol.

A)0.00
B)-397.9
C)+397.9
D)-795.8
E)+795.8

Question 79

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

Question 80

The value of ΔH° for the formation of POCl₃ from its constituent elements, P₂ (g)+ O₂ (g)+ 3Cl₂ (g)→ 2POCl₃ (g)
Is ________ kJ/mol.

A)-1228.7
B)-397.7
C)-686.5
D)+1228.7
E)+686.5