Chemistry B1B
Exam IA
Name:__________________
Section:_________________
Date:_____________
Circle the correct answer
1. Thermodynamics is applied to learn a reaction’s
[A] feasibility.
[B] mechanism.
[C] rate.
[D] stoichiometry.
[E] pathway.
2. Which of the following is (are) spontaneous process(es)?
1. Ice melting at 25°C
2. Heat flowing from a hot object to a cold object
3. An iron tool rusting
[A] 1 only
[B] 2 only
[C] 3 only
[D] 1 and 3 only
[E] 1, 2, and 3
3. A reaction must be spontaneous at all temperatures when
[A] H is negative and S is positive.
[C] H is negative and S is negative.
[E] G is negative.
[B] H is positive and S is positive.
[D] H is positive and S is negative.
4. Which of the following would be expected to have the LARGEST entropy value per mole?
[A] SO3(g)
[B] S2(g)
[C] SO2(g)
[D] S8(g)
[E] S(g)
5. Which symbol is used to represent the change of heat at constant pressure?
[A] TS
[B] H
[C] G
[D] U
[E] S
6. Which of the following reactions has the largest positive value of S per mole of O2?
[A] 2C(s) + O2(g) 
2CO(g)

[C] C(s) + O2(g) 
CO2(g)

[E] 2Mg(s) + O2(g) 
2MgO(s)

[B] 2H2(g) + O2(g) 
2H2O(g)

[D] 2NO(g) + O2(g) 
2NO2(g)

7. What is the thermodynamic quantity that provides the criterion for the spontaneity of a
chemical reaction?
[A] TS
[B] H
[C] G
[D] U
[E] S
8. If an ideal gas is expanded from 1.00 L to 5.00 L at constant temperature, then the following
must be true:
[A] U = 0 and S > 0.
[D] U > 0 and S > 0.
[B] U > 0 and S < 0.
[E] U < 0 and S < 0.
[C] U = 0 and S < 0.
9. All the following have free energy of formation values of zero EXCEPT
[A] U(s).
[B] H(g).
[C] Ni(s).
[D] He(g).
[E] Ca(s).
10. H and U are nearly the same in all the following processes EXCEPT
[A] C6H6(s) 
C6H6(l).

[C] CH4(g) + Cl2(g) 
CH3Cl(g) + HCl(g).

[D] CuO(s) + H2(g) 
Cu(s) + H2O(g).

[B] 3O2(g) 
2O3(g).

[E] F2(g) + H2(g) 
2HF(g).

11. The total entropy of a system and its surroundings always increases for a spontaneous
process. This is a statement of
[A] the law of conservation of matter.
[C] the third law of thermodynamics.
[E] the law of constant composition.
[B] the first law of thermodynamics.
[D] the second law of thermodynamics.
12. Which of the following must have a positive value for an endothermic reaction?
[A] Equilibrium constant
[D] Free energy change
[B] Entropy change
[E] Enthalpy change
[C] Electrode cell potential
13. The best criterion for the spontaneity of a chemical reaction is the sign of
[A] G.
[B] H.
[C] G.
[D] TS.
[E] H.
14. For a reaction if G  0, then
[A] S  0. [B] H  0. [C] G  0. [D] K  1.
[E] K  0.
15. An ideal fuel for the control jet of a space vehicle should decompose with
[A] G  0 and H  0.
[D] G  0 and H  0.
[B] G  0 and H  0.
[E] G  0 and H  0.
[C] G  0 and H  0.
16. In which of the following processes would one expect S to have the value closest to zero?
[A] CH3C(O)H(g) +
5
2
O2(g) 
2CO2(g) + 2H2O(g)

[B] C2H4(g) + Br2(l) 
C2H4Br2(l)

[D] N2(g) + O2(g) 
2NO(g)

[C] 2NO(g) + O2(g) 
2NO2(g)

[E] H2(g) + I2(s) 
2HI(g)

17. Which of the following is true in the sublimation of one mole of dry ice?
1. The entropy decreases.
2. The entropy increases.
3. The enthalpy increases.
4. The enthalpy decreases.
[A] 1 only
[B] 2 only
[C] 1 and 3 only
[D] 2 and 3 only
[E] 1 and 4 only
18. Which of the following processes involve an increase in entropy?
1. Br2(l) 
Br2(g)

2. (NH4)2Cr2O7(s) 
N2(g) + 4H2O(l) + Cr2O3(s)

3. 2KClO3(s) 
2KCl(s) + 3O2(g)

4. 2HgO(s) 
2Hg(l) + O2(g)

[A] 1 only
[B] 2 only
[C] 3 and 4 only
[D] 1, 3, and 4 only
[E] 1, 2, 3, and 4
19. What is equal to H at equilibrium?
[A] TS
[B] H
[C] G
[D] U
[E] S
20. The temperature of water decreases on the dissolution of NH4NO3. From this observation we
can conclude that the solution process would be best described as
[A] exothermic with a negative free energy change.
[B] exothermic with a negative entropy change.
[C] endothermic with a positive entropy change.
[D] endothermic with a negative entropy change.
[E] exothermic with a positive entropy change.
Reference: [19.1.7]
[1] [A]
Reference: [19.1.15]
[2] [E]
Reference: [19.1.64]
[3] [A]
Reference: [19.1.20]
[4] [D]
Reference: [19.1.1]
[5] [B]
Reference: [19.1.34]
[6] [A]
Reference: [19.1.2]
[7] [C]
Reference: [19.1.19]
[8] [A]
Reference: [19.1.56]
[9] [B]
Reference: [19.1.11]
[10] [B]
Reference: [19.1.14]
[11] [D]
Reference: [19.1.6]
[12] [E]
Reference: [19.1.44]
[13] [C]
Reference: [19.1.79]
[14] [D]
Reference: [19.2.87]
[15] [E]
Reference: [19.1.25]
[16] [D]
Reference: [19.1.13]
[17] [D]
Reference: [19.1.29]
[18] [E]
Reference: [19.1.4]
[19] [A]
Reference: [19.1.54]
[20] [C]
Solve the following problems. Show all your work. (All problems worth 5 points)
1.
Given that:
S(s) + O2(g)  SO2 (g)
2SO3 (g)  2 SO2 (g) + O2 (g)
H = -295.8 kJ/mol
H = +197.8 kJ/mol
Determine the enthalpy change and the change in internal energy for the reaction:
2 S(s) + 3 O2(g)  2 SO3(g)
2.
H = ???
Given the following information for the reaction that is carried out at 25oC, calculate Go
for the reaction at 25oC. Interpret what the value of Go is telling you.
2 A (g) + B (g)  C (g)
Substance
A(g)
B(g)
C(g)
Hfo (kJ/mol)
191
70.8
-197
So (J/molK)
244
300
164
3.
4.
A sample of an ideal gas is allowed to escape reversibly and isothermally into a vacuum.
Which of the following statements is correct? Explain.
1.
w = 0, E = q = a positive number
2.
w = PV + VP
3.
w = PV, E = 0, q = -PV and is a negative number
4.
E = 0, q = -w = a positive number
5.
w = 0, q = 0, E = 0
What is the free energy change, G, when 1.0 mole of water is converted, at 100oC and 1
atm, to steam at 100oC and 1 atm in a reversible manner?
Hvap(H2O) = 40.6 kJ/mole.
5.
Calculate the solubility product (Ksp) for Mg(OH)2 at 25oC. The Gfo values are given in
the table.
Species
Mg2+(aq)
OH-(aq)
Mg(OH)2(s)
o
-454.8
-157.3
-833.7
Gf
6.
Is the reaction of magnesium carbonate decomposing to magnesium oxide and carbon
dioxide spontaneous at 1000oC? Values of Hfo and So are given in the table. (Extra
credit- At what temperature does this reaction become spontaneous?)
Species
Hfo (kJ/mol)
So(J/K)
g (s)
-601.2
26.9
CO2 (g)
-110.5
213.7
Mg(OH)2(s)
-1111.7
65.9