Test Bank General Chemistry, 10th edition 1
Chapter 18 – Thermodynamics and Equilibrium
1. Which of the following is not a state function?
A)
w
B)
H
C)
P
D)
U
E)
T
2. According to the first law of thermodynamics, the energy of the universe is constant. Does
this mean that E is always equal to zero?
A)
No, E does not always equal zero, but this is due only to factors such as friction
and heat.
B)
No, E never equals zero because energy is always flowing between the system
and the surroundings.
C)
No, E does not always equal zero because it refers to the system’s internal energy,
which is affected by heat and work.
D)
Yes, E = 0 at all times, which is why q = –w.
E)
No, E never equals zero because work is always being done on the system or by
the system.
3. For the isothermal (constant-temperature) expansion of an ideal gas,
A)
w > 0 and q < 0.
B)
w = 0 and q > 0.
C)
w < 0 and q = 0.
D)
w < 0 and q > 0.
E)
w > 0 and q > 0.
4. H and U are nearly the same in all the following processes except
A)
F2(g) + H2(g) → 2HF(g).
B)
CH4(g) + Cl2(g) → CH3Cl(g) + HCl(g).
C)
C6H6(s) → C6H6(l).
D)
CuO(s) + H2(g) → Cu(s) + H2O(g).
E)
3O2(g) → 2O3(g).
5. A gas absorbs 0.0 J of heat and then performs 77.0 J of work. What is the change in internal
energy of the gas?
A)
–77.0 J
B)
37.0 J
C)
117.0 J
D)
76.6 J
E)
none of these
6. For a particular process, q = 20 kJ and w = 15 kJ. Which of the following statements is true?
A)
U = 35 kJ.
B)
The system does work on the surroundings.
C)
Heat flows from the system to the surroundings.
D)
All of the above are true.
E)
None of the above are true.
7. What is the change in internal energy of the system (U) if 36 kJ of heat energy is absorbed
by the system and 84 kJ of work is done by the system for a certain process?
A)
–48 kJ
B)
120 kJ
C)
36 kJ
D)
48 kJ
E)
–120 kJ
Test Bank General Chemistry, 10th edition 3
8. What is the change in internal energy (U) of the system if q = –55 kJ and w = 58 kJ for a
certain process?
A)
3 kJ
B)
–113 kJ
C)
113 kJ
D)
–3 kJ
E)
–55 kJ
9. A system under constant external pressure undergoes an increase in volume. What is the
effect on the surroundings?
A)
Energy is transferred as pressure-volume work done on the surroundings.
B)
Energy is transferred as pressure-volume work done by the surroundings on the
system.
C)
Energy is transferred as heat from the system to the surroundings.
D)
Energy is transferred as heat from the surroundings to the system.
E)
None of the above.
10. In which of the following scenarios is no change in the internal energy of the system
possible?
A)
q < 0, w > 0
B)
q > 0, w > 0
C)
q = 0, w > 0
D)
q < 0, w = 0
E)
q < 0, w < 0
11. Under what conditions does q, the heat evolved or absorbed by the system in a physical or
chemical process, equal the change in enthalpy of the system?
1.
When q 0.
2.
When w = 0.
3.
When w = −PV.
A)
1 only
B)
2 only
C)
3 only
D)
2 and 3
E)
1, 2, and 3
12. Which of the following statements concerning entropy change is/are true?
1.
For a spontaneous process, .
2.
For a spontaneous process, .
3.
For an equilibrium process (such as a phase change), .
A)
1 only
B)
2 only
C)
3 only
D)
2 and 3
E)
1, 2, and 3
13. Which of the following statements concerning entropy is/are true?
1.
On a per mole basis, the solid form of a particular substance has a greater
entropy than its gaseous form.
2.
On a per mole basis at a fixed temperature, larger gaseous molecules tend to
have a greater entropy than smaller gaseous molecules because of a greater
number of comformations over which to disperse energy.
3.
On a per mole basis, the liquid form of a particular substance has a greater
entropy than the solid form of the substance.
A)
1 only
B)
2 only
C)
3 only
D)
2 and 3
E)
1, 2, and 3
14. Which of the following is true for the sublimation of a solid substance?
A)
S = 0 and H = 0.
B)
S < 0 and H < 0.
C)
S < 0 and H > 0.
D)
S > 0 and H > 0.
E)
S > 0 and H < 0.
15. Which of the following has the lowest entropy per mole?
A)
liquid sodium at 100°C
B)
gaseous sodium at 900°C and 0.5 atm
C)
a solid solution of sodium in potassium at 30°C
D)
gaseous sodium at 900°C and 1 atm
E)
solid sodium at 30°C
16. Which of the following compounds has the highest standard entropy per mole at 298 K?
A)
H2O(l)
B)
CaCO3(s)
C)
CO(g)
D)
SiO2(s)
E)
CH3OH(l)
17. The total entropy of a system and its surroundings always increases for a spontaneous
process. This is a statement of
A)
the third law of thermodynamics.
B)
the law of constant composition.
C)
the second law of thermodynamics.
D)
the law of conservation of matter.
E)
the first law of thermodynamics.
18. The standard enthalpy of vaporization of Freon-10, CCl4, is 29.82 kJ/mol at its normal
boiling point of 77°C. What is the change of entropy for 1 mol of liquid Freon-10 when it
vaporizes at its normal boiling point?
A)
8.52 10–2 J/K
B)
1.04 104 J/K
C)
85.2 J/K
D)
0.387 J/K
E)
3.87 102 J/K
19. The standard enthalpy of vaporization of chloroform is 29.2 kJ/mol at its normal boiling
point, 61.2°C. What is the standard change in entropy for the vaporization of chloroform at
its normal boiling point?
A)
87.3 J/(mol · K)
B)
–29.2 J/(mol · K)
C)
0.477 J/(mol · K)
D)
0.0873 J/(mol · K)
E)
477 J/(mol · K)
20. The standard enthalpy of fusion of bromobenzene is 10.7 kJ/mol at its melting point,
242.4 K. What is the standard change in entropy for the melting of bromobenzene at its
melting point?
A)
0.0208 J/(mol · K)
B)
44.1 J/(mol · K)
C)
–10.7 J/(mol · K)
D)
–348 J/(mol · K)
E)
0.0441 J/(mol · K)
Test Bank General Chemistry, 10th edition 7
21. At the normal boiling point of o-xylene, H°vap = 36.2 kJ/mol and S°vap = 86.7 J/(mol · K).
What is the normal boiling point of o-xylene?
A)
314 K
B)
373 K
C)
115 K
D)
867 K
E)
418 K
22. The enthalpy of vaporization (H°vap) of benzene is 30.7 kJ/mol at its normal boiling point
of 353.3 K. What is S°vap at this temperature?
A)
86.9 J/(mol·K)
B)
0.087 J/(mol·K)
C)
11.5 J/(mol·K)
D)
0.0115 J/(mol·K)
E)
383 J/(mol·K)
23. Assuming H and S are constant with respect to temperature, under what conditions will a
chemical reaction be spontaneous only at low temperatures?
A)
H is negative, and S is negative.
B)
H is positive, and S is positive.
C)
S = 0, and H is positive.
D)
H = 0, and S is negative.
E)
none of these
24. Which of the following is not a spontaneous process at 25°C and 1 atm pressure?
A)
salt dissolving
B)
ice melting
C)
water boiling
D)
iron rusting
E)
steam condensing
25. The third law of thermodynamics states that
A)
the entropy of the universe is increasing.
B)
the entropy of the universe is constant.
C)
the entropy of the universe equals the sum of the entropy of system and that of the
surroundings.
D)
the absolute entropy of a substance decreases with increasing temperature.
E)
the entropy is zero at 0 K for a perfect crystal.
26. In which reaction is S° expected to be negative?
A)
2C2H6(g) + 7O2(g) → 4CO2(g) + 6H2O(l)
B)
Ga(l) → Ga(s)
C)
H2O(l) + 2SO2(g) → H2SO4(l)
D)
CO2(g) → CO2(s)
E)
all of above
27. For which of the following processes would S° be expected to be most positive?
A)
H2O(l) → H2O(s)
B)
NH3(g) + HCl(g) → NH4Cl(s)
C)
O2(g) + 2H2(g) → 2H2O(g)
D)
N2O4(g) → 2NO2(g)
E)
2NH4NO3(s) → 2N2(g) + O2(g) + 4H2O(g)
Test Bank General Chemistry, 10th edition 9
28. For which of the following reactions is S° at 25°C closest to zero?
A)
N2(g) + O2(g) → 2NO(g)
B)
H2(g) + I2(s) → 2HI(g)
C)
CH3CHO(g) + 5/2O2(g) → 2CO2(g) + 2H2O(g)
D)
2NO(g) + O2(g) → 2NO2(g)
E)
C2H4(g) + Br2(l) → C2H4Br2(l)
29. For which of the following reactions is S° > 0 at 25°C?
A)
2H2(g) + O2(g) → 2H2O(g)
B)
2ClBr(g) → Cl2(g) + Br2(g)
C)
I2(g) → I2(s)
D)
2NO(g) + O2(g) → 2NO2(g)
E)
NH4HS(s) → NH3(g) + H2S(g)
30. Which of the following reactions has the smallest value of S° at 25°C?
A)
C6H6(l) + 9/2O2(g) → 6CO(g) + 3H2O(g)
B)
C6H6(s) → C6H6(l)
C)
C6H6(l) + Br2(l) → C6H5Br(l) + HBr(g)
D)
C6H6(s) → C6H6(g)
E)
C6H6(l) + 15/2O2(g) → 6CO2(g) + 3H2O(g)
31. For which of the following reactions is S° < 0 at 25°C?
A)
2KClO3(s) → 2KCl(s) + 3O2(g)
B)
2HgO(s) → 2Hg(l) + O2(g)
C)
Br2(l) → Br2(g)
D)
P4(s) + 5O2(g) → P4O10(s)
E)
(NH4)2Cr2O7(s) → N2(g) + 4H2O(l) + Cr2O3(s)
Test Bank General Chemistry, 10th edition 10
32. Arrange the following reactions in order of increasing S° value.
1.
H2(g) + F2(g) → 2HF(g)
2.
NH4NO3(s) → N2O(g) + 2H2O(l)
3.
(NH4)2Cr2O7(s) → Cr2O3(s) + 4H2O(l) + N2(g)
A)
1 < 2 < 3
B)
2 < 3 < 1
C)
3 < 1 < 2
D)
1 < 3 < 2
E)
2 < 1 < 3
33. For which of the following reactions is S° > 0 at 25°C?
A)
MgO(s) + CO2(g) → MgCO3(s)
B)
2H2(g) + O2(l) → 2H2O(l)
C)
2Li(s) + O2(g) → Li2O(s)
D)
2CO(g) + O2(g) → 2CO2(g)
E)
F3BNH3(s) → BF3(g) + NH3(g)
34. Which of the following reactions has the largest positive value of S° per mole of O2 at
25°C?
A)
2H2(g) + O2(g) → 2H2O(g)
B)
2C(s) + O2(g) → 2CO(g)
C)
2Mg(s) + O2(g) → 2MgO(s)
D)
C(s) + O2(g) → CO2(g)
E)
2NO(g) + O2(g) → 2NO2(g)
35. For the process Cl2(g) → 2Cl(g),
A)
H is + and S is + for the reaction.
B)
H is + and S = 0 for the reaction.
C)
H is – and S is – for the reaction.
D)
H is – and S is + for the reaction.
E)
H is + and S is – for the reaction.
36. For the reaction N2(g) → 2N(g),
A)
H < 0 and S < 0.
B)
H > 0 and S < 0.
C)
H < 0 and S > 0.
D)
H = 0 and S > 0.
E)
H > 0 and S > 0.
37. Given the following, determine S° at 298 K for one mole of NO(g).
2NO(g) + O2(g) → 2NO2(g); S = −146.7 J/K at 298K
Substance
S° (J/(mol · K)) at 298 K
NO(g)
?
O2(g)
205.1
NO2(g)
240.0
A)
210.9 J/K
B)
−90.85 J/K
C)
421.7 J/K
D)
–421.7 J/K
E)
+90.85 J/K
38. What is the change in entropy when 0.100 g of silicon is burned in excess oxygen to yield
silicon dioxide at 298 K?
Si(s) + O2(g) → SiO2(s); S° = –182.4 J/K at 298 K
A)
–182 J/K
B)
–18.2 J/K
C)
–2.18 10–3 J/K
D)
–5.12 104 J/K
E)
–0.649 J/K
39. What is the change in entropy when 0.646 g of water decomposes to form hydrogen gas and
oxygen gas at 298 K?
2H2O(l) → 2H2(g) + O2(g); S° = 326.3 J/K at 298 K
A)
5.85 J/K
B)
0.0785 J/K
C)
23.4 J/K
D)
11.7 J/K
E)
211 J/K
40. What is the change in entropy when 5.46 mL of liquid benzene (C6H6, d = 0.879 g/mL) is
combusted in the presence of 27.3 L of oxygen gas, measured at 298 K and 1 atm pressure?
(R = 0.0821 L · atm/(K · mol))
2C6H6(l) + 15O2(g) → 12CO2(g) + 6H2O(l); S° = –437.7 J/K at 298 K
A)
–488 J/K
B)
–46.0 J/K
C)
–26.9 J/K
D)
–13.4 J/K
E)
–515 J/K
41. Which of the following equations is correct?
A)
G = S – TH
B)
G = H – PV
C)
G = H – TS
D)
G = Ginitial – Gfinal
E)
G = S – PV
42. The free-energy change of a reaction is a measure of
A)
the excess entropy given off to the reaction system.
B)
the increased molecular disorder that occurs in the system.
C)
the energy given off to the surroundings.
D)
the direction in which a net reaction occurs.
E)
the excess entropy given off to the surroundings.
43. What is the thermodynamic quantity that provides the criterion for the spontaneity of a
chemical reaction?
A)
TS
B)
U
C)
S
D)
G
E)
H
44. Which of the following is the best criterion for determining the spontaneity of a chemical
reaction?
A)
H
B)
H°
C)
G
D)
G°
E)
TS
45. What is G° at 298 K for the following reaction?
I2(g) + Br2(g) → 2IBr(g); H° = –11.6 kJ; S° = 12 J/K at 298 K
A)
–8.02 kJ
B)
15.2 kJ
C)
–15.2 kJ
D)
3.59 103 kJ
E)
–3.59 103 kJ
46. From these two reactions at 298 K,
V2O3(s) + 3CO(g) → 2V(s) + 3CO2(g); H° = 369.8 kJ; S° = 8.3 J/K
V2O5(s) + 2CO(g) → V2O3(s) + 2CO2(g); H° = –234.2 kJ; S° = 0.2 J/K
calculate G° for the following at 298 K:
2V(s) + 5CO2(g) → V2O5(s) + 5CO(g)
A)
+133.1 kJ
B)
+601.6 kJ
C)
–601.6 kJ
D)
–133.1 kJ
E)
+1.6 kJ
47. What is S° at 298 K for the following reaction?
CH4(g) + N2(g) → HCN(g) + NH3(g); H° = 164.1 kJ; G° = 159.1 kJ at 298 K
A)
2.0 J/K
B)
5.5 102 J/K
C)
1.1 103 J/K
D)
5.3 102 J/K
E)
17 J/K
48. Which of the following has a value of zero for the standard free energy of formation at
298 K?
A)
I(l)
B)
I2(g)
C)
I2(l)
D)
I2(s)
E)
I(g)
49. For which of the following substances is the standard free energy of formation not equal to
zero at 298 K?
A)
Ne(g)
B)
Gd(s)
C)
O2(g)
D)
Be(g)
E)
Cu(s)
50. Given the following, determine G°f at 298 K for SnO.
Sn(s) + SnO2(s) → 2SnO(s) ; G° = 12.0 kJ at 298K
Substance
G°f (kJ/mol) at 298 K
SnO(s)
?
SnO2(s)
–515.8
A)
–251.9 kJ/mol
B)
–503.8 kJ/mol
C)
527.8 kJ/mol
D)
263.9 kJ/mol
E)
1055.6 kJ/mol
51. Given the following, determine G° at 298 K for the precipitation reaction,
Ag+(aq) +Cl−(aq) → AgCl(s)
Substance
G°f (kJ/mol) at 298 K
Cl−(aq)
–131.3
Ag+(aq)
AgCl(s)
–109.8