Deck 19: Chemical Thermodynamics

Question 1

ΔS is positive for the reaction __________.

A)2NO (g)+ O₂ (g)→ 2NO₂ (g)
B)2N₂ (g)+ 3H₂ (g)→ 2 NH₃ (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)

Answer 1

C₃H₈ (g)+ 5 O₂ (g)→ 3CO₂ (g)+ 4 H₂O (g)

Question 2

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

Answer 2

dissolving oxygen in water

Question 3

The thermodynamic quantity that expresses the degree of disorder in a system is __________.

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

Answer 3

entropy

Question 4

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 5

The first law of thermodynamics can be given as __________.

A)ΔE = q + w
B)
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 = q_rev/T at constant temperature

Question 6

The entropy of the universe is __________.

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

Question 7

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 = klnW
E)S = Wk

Question 8

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

Question 9

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 10

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 11

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 12

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

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

Question 13

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

A)boiling water to form steam
B)dissolution of solid KCl in water
C)mixing of two gases into one container
D)freezing water to form ice
E)melting ice to form water

Question 14

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

Question 15

For an isothermal process, ΔS = __________.

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

Question 16

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 17

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 18

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 19

The second law of thermodynamics states that __________.

A)ΔE = q + w
B)
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 20

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 21

For a reaction to be spontaneous under standard conditions at all temperatures, the signs of ΔH° and ΔS° must be __________ and __________, respectively.

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

Question 22

ΔS is negative for the reaction __________.

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

Question 23

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

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

Question 24

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

Question 25

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 26

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

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

Question 27

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 __________.

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 28

ΔS is negative for the reaction __________.

A)2H₂O (g)→ 2H₂ (g)+ O₂ (g)
B)Mg(NO₃)₂ (aq)+ 2NaOH(aq)→ Mg(OH)₂ (s)+ 2NaNO₃ (aq)
C)H₂O (l)→ H₂O (g)
D)C₆H₁₂O₆ (s)→ 6C (s)+ 6H₂ (g)+ 3O₂ (g)
E)NaCl (aq)→ Na⁺ (aq)+ Cl^- (aq)

Question 29

Which reaction produces a decrease in the entropy of the system?

A)4 NH₃ (g)+ 5 O₂ (g)→ 4 NO (g)+ 6 H₂O (g)
B)Na (s)+ 1/2Cl₂ (g)→ NaCl (s)
C)2 HgO (s)→ 2 Hg (l)+ O₂ (g)
D)U (s)+ 3F₂ (g)→ UF₆ (s)
E)H₂O (s)→ H₂O (g)

Question 30

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

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 31

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

Question 32

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)Pb⁺² (aq)+ 2Cl^- (aq)→ PbCl₂ (s)
E)CO₂ (g)→ CO₂ (s)

Question 33

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

A)H₂
B)C₂H₆
C)C₂H₂
D)CH₄
E)C₂H₄

Question 34

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 35

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 36

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 37

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)→ 2HCl (g)
D)N₂ (g)+ 3H₂ (g)→ 2NH₃ (g)
E)H₂O (l)→ H₂O (s)

Question 38

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 39

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 40

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

A)H₂O (s)
B)H₂O (l)
C)H₂O (g)
D)H₂S (g)
E)H₂S (l)

Question 41

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 42

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 43

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 44

The combustion of hydrogen in the presence of excess oxygen yields water: 2H₂(g)+ O₂(g)→ 2H₂O (l)
The value of ΔS° for this reaction is __________ J/K∙ mol.

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

Question 45

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 46

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

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

Question 47

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 48

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 49

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 50

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 51

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 52

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 53

Consider the reaction: FeO (s)+ Fe (s)+ O₂ (g)→ Fe₂O₃ (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)756.3
D)2438
E)1235

Question 54

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 55

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 56

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 57

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 58

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 59

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 60

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 61

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 62

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 63

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 64

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 65

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

Question 66

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 67

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 68

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 69

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 70

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 71

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 72

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 73

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 74

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 75

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 76

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 77

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 78

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 79

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 80

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