THERMODYNAMICS
CHAPTER 18 WORKSHEET
Name: __________________________
Date: _____________
1. Which of the following is not a state function?
A) w
B) H
C) U
D) P
E) T
2. According to the first law of thermodynamics, the energy of the universe is constant.
Does this mean that ΔE is always equal to zero?
A) Yes, ΔE = 0 at all times, which is why q = -w.
B) No, ΔE does not always equal zero, but this is due only to factors such as friction
and heat.
C) No, ΔE does not always equal zero because it refers to the system's internal energy,
which is affected by heat and work.
D) No, ΔE never equals zero because work is always being done on the system or by
the system.
E) No, ΔE never equals zero because energy is always flowing between the system and
the surroundings.
3. Which of the following is true for the deposition of CO2(g)?
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.
4. The standard enthalpy of vaporization of Freon-13, CF3Cl, is 15.65 kJ/mol at its normal
boiling point of –82°C. What is the change of entropy for 1 mol of liquid Freon-13
when it vaporizes at its normal boiling point?
A) 81.9 J/K
B) –0.191 J/K
C) –1.91 × 102 J/K
D) 8.19 × 10–2 J/K
E) 2.99 × 103 J/K
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5. In which reaction is S° expected to be positive?
A) I2(g) I2(s)
B) H2O(1) H2O(s)
C) CH3OH(g) + 3 2 O2(g) CO2(g) + 2H2O(l)
D) 2O2(g) + 2SO(g) 2SO3(g)
E) none of these
6. What is the change in entropy when 0.163 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) –29.7 J/K
B) –3.14 104 J/K
C) –1.06 J/K
D) –182 J/K
E) –3.55  10–3 J/K
7. Which of the following equations is correct?
A) G = S – TH
B) G = Ginitial – Gfinal
C) G = H – TS
D) G = S – PV
E) G = H – PV
8. What is G° at 298 K for the following reaction?
Pb(s) + PbO2(s) 2PbO(s)
Substance G°f (kJ/mol) at 298 K
PbO(s)
–187.9
PbO2(s)
–217.3
A) 158.5 kJ
B) –158.5 kJ
C) 29.4 kJ
D) –405.2 kJ
E) –29.4 kJ
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9. Consder the following reaction:
3C(s) + 4H2(g) C3H8(g); H° = –104.7 kJ; S° = –287.4 J/K at 298 K
What is the equilibrium constant at 298 K for this reaction?
A) 1.0
B) 2.2 103
C) 4.6 10–4
D) 2.2 1018
E) 1.0  10–15
10. What is
+
Ag
A)
B)
C)
D)
E)
G° at 298 K for the following equilibrium?
(aq) + 2NH3(aq)
–41 kJ
41 kJ
–18 kJ
18 kJ
0
Ag(NH3)2+(aq); Kf = 1.7 × 107 at 298 K
11. A certain reaction has negative values for both H and S. Therefore, the reaction
A) must be spontaneous at all temperatures.
B) cannot be spontaneous at any temperature.
C) can be spontaneous if the temperature is high enough.
D) can be spontaneous if the temperature is low enough.
E) has a positive free energy at any temperature.
12. Which of the following statements is true for the following reaction?
NH4HS(s) NH3(g) + H2S(g); H° = 93 kJ
A) The reaction is not spontaneous at any temperature.
B) The reaction is spontaneous at all temperatures.
C) The reaction is spontaneous only at relatively low temperatures.
D) The reaction is spontaneous only at relatively high temperatures.
E) The reaction is at equilibrium under standard-state conditions.
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Answer Key
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
12.
A
C
A
A
E
C
C
B
B
A
D
D
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