Chapter 16- chemical thermodynamics

Beschreibung

Originally chapter 19
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Zusammenfassung der Ressource

Frage 1

Frage
The first law of thermodynamics can be given as __________.
Antworten
  • 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 = qrev/T at constant temperature

Frage 2

Frage
Of the following, only __________ is not a state function.
Antworten
  • A) S
  • B) H
  • C) q
  • D) E
  • E) T

Frage 3

Frage
When a system is at equilibrium, __________.
Antworten
  • 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

Frage 4

Frage
A reversible process is one that __________.
Antworten
  • 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

Frage 5

Frage
Which of the following statements is true?
Antworten
  • 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.

Frage 6

Frage
For an isothermal process, ΔS = __________.
Antworten
  • A) q
  • B) qrev/T
  • C) qrev
  • D) Tqrev
  • E) q + w

Frage 7

Frage
Which one of the following is always positive when a spontaneous process occurs?
Antworten
  • A) ΔSsystem
  • B) ΔSsurroundings
  • C) ΔSuniverse
  • D) ΔHuniverse
  • E) ΔHsurroundings

Frage 8

Frage
The second law of thermodynamics states that __________.
Antworten
  • 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 = qrev/T at constant temperature

Frage 9

Frage
Which of the following statements is false?
Antworten
  • 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.

Frage 10

Frage
Which one of the following processes produces a decrease of the entropy of the system?
Antworten
  • A) dissolving sodium chloride in water
  • B) sublimation of naphthalene
  • C) dissolving oxygen in water
  • D) boiling of alcohol
  • E) explosion of nitroglycerine

Frage 11

Frage
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?
Antworten
  • A) melting the solid
  • B) heating the liquid
  • C) heating the gas
  • D) heating the solid
  • E) vaporizing the liquid

Frage 12

Frage
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?
Antworten
  • A) S = kW
  • B) S = k/W
  • C) S = W/k
  • D) S = klnW
  • E) S = Wk

Frage 13

Frage
ΔS is positive for the reaction __________.
Antworten
  • 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)

Frage 14

Frage
Which reaction produces an increase in the entropy of the system?
Antworten
  • 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)

Frage 15

Frage
Of the following, the entropy of __________ is the largest.
Antworten
  • A) HCl (l)
  • B) HCl (s)
  • C) HCl (g)
  • D) HBr (g)
  • E) HI (g)

Frage 16

Frage
Of the following, the entropy of gaseous __________ is the largest at 25°C and 1 atm.
Antworten
  • A) CH3OH
  • B) C2H5OH
  • C) C3H7OH
  • D) CH4
  • E) C4H10

Frage 17

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

Frage 18

Frage
The equilibrium position corresponds to which letter on the graph of G vs. f (course of reaction) below?
Antworten
  • A) A
  • B) B
  • C) C
  • D) D
  • E) E

Frage 19

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

Frage 20

Frage
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 __________.
Antworten
  • 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

Frage 21

Frage
A reaction that is not spontaneous at low temperature can become spontaneous at high temperature if ΔH is __________ and ΔS is __________.
Antworten
  • A) +, +
  • B) -, -
  • C) +, -
  • D) -, +
  • E) +, 0

Frage 22

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

Frage 23

Frage
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.
Antworten
  • A) 1230 °C
  • B) 150 °C
  • C) 432 °C
  • D) 133 °C
  • E) 1640 °C

Frage 24

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

Frage 25

Frage
With thermodynamics, one cannot determine __________.
Antworten
  • 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

Frage 26

Frage
If ΔG° for a reaction is greater than zero, then __________.
Antworten
  • A) K = 0
  • B) K = 1
  • C) K > 1
  • D) K < 1
  • E) More information is needed.

Frage 27

Frage
The value of ΔS° for the catalytic hydrogenation of ethene to ethane, C2H4 (g) + H2(g) → C2H6 (g) is __________ J/K∙ mol.
Antworten
  • A) -101.9
  • B) -120.5
  • C) -232.5
  • D) +112.0
  • E) +101.9

Frage 28

Frage
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.
Antworten
  • A) +424.3
  • B) +205.0
  • C) -205.0
  • D) -2.9
  • E) +2.9

Frage 29

Frage
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.
Antworten
  • A) +790.4
  • B) -790.4
  • C) +395.2
  • D) -395.2
  • E) +105.1

Frage 30

Frage
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.
Antworten
  • A) +740.8
  • B) -370.4
  • C) +370.4
  • D) -740.8
  • E) +185.2

Frage 31

Frage
Given the thermodynamic data in the table below, calculate the equilibrium constant (at 298 K) for the reaction: 2SO2 (g) + O2 (g) --> 2SO3 (g)
Antworten
  • A) 2.37 × 1024
  • B) 1.06
  • C) 1.95
  • D) 3.82 × 1023
  • E) More data are needed.

Frage 32

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

Frage 33

Frage
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?
Antworten
  • A) 88.8
  • B) -88.8
  • C) -238
  • D) 373
  • E) -40.7

Frage 34

Frage
The standard Gibbs free energy of formation of __________ is zero. (a) H2O (l) (b) O (g) (c) I2 (s)
Antworten
  • A) (a) only
  • B) (b) only
  • C) (c) only
  • D) (b) and (c)
  • E) (a), (b), and (c)

Frage 35

Frage
The standard Gibbs free energy of formation of __________ is zero. (a) H2O (l) (b) Mg (s) (c) Br2 (l)
Antworten
  • A) (a) only
  • B) (b) only
  • C) (c) only
  • D) (b) and (c)
  • E) (a), (b), and (c)

Frage 36

Frage
The standard Gibbs free energy of formation of __________ is zero. (a) Si (s) (b) F2 (g) (c) Ni (s)
Antworten
  • A) (a) only
  • B) (b) only
  • C) (c) only
  • D) (b) and (c)
  • E) (a), (b), and (c)

Frage 37

Frage
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.
Antworten
  • A) -612.3
  • B) 3.65 × 104
  • C) 1.08 × 105
  • D) -683.3
  • E) -829.7

Frage 38

Frage
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.
Antworten
  • A) 273
  • B) 325
  • C) 552
  • D) 756
  • E) 1029

Frage 39

Frage
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.
Antworten
  • A) at T < 425 K
  • B) at T > 425 K
  • C) at all temperatures
  • D) at T > 298 K
  • E) at T < 298 K

Frage 40

Frage
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 __________.
Antworten
  • A) -1.8
  • B) -3.86 × 103
  • C) -7.25 × 103
  • D) -104.5
  • E) -40.5

Frage 41

Frage
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 __________.
Antworten
  • A) -44.2
  • B) -3.88 × 103
  • C) -7.28 × 103
  • D) -708.4
  • E) -649.5

Frage 42

Frage
15) The equilibrium constant for a reaction is 0.35 at 25°C. What is the value of ΔG° (kJ/mol) at this temperature?
Antworten
  • A) 2.6
  • B) -4.2
  • C) 220
  • D) 4.2
  • E) More information is needed.

Frage 43

Frage
A reversible change produces the maximum amount of ________ that can be achieved by the system on the surroundings.
Antworten
  • A) Energy
  • B) Product
  • C) Reactant
  • D) Work

Frage 44

Frage
The melting of a substance at its melting point is an isothermal process.
Antworten
  • True
  • False

Frage 45

Frage
The vaporization of a substance at its boiling point is an isothermal process
Antworten
  • True
  • False

Frage 46

Frage
The entropy of a pure crystalline substance at 0°C is zero.
Antworten
  • True
  • False

Frage 47

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