Chemistry 116: General Chemistry
Syracuse University Project Advance
2014 Spring Exam #3
Name
Date
1. In which reaction is S˚ expected to be positive?
A.
B.
C.
D.
E.
I2(g)  I2(s)
O2(g) + 2SO2(g)  2SO3(g)
2CH3OH(g) + 3O2(g)  2CO2(g) + 4H2O(l)
H2O(l)  H2O (s)
none of the above
2. A reaction is spontaneous when
A.
B.
C.
D.
E.
G˚ is negative or E˚ is positive.
G˚ is negative or E˚ is negative.
G˚ is positive or E˚ is negative.
G˚ is positive or E˚ is positive.
G˚ is negative, H˚ is negative, and E˚ is negative.
3. Assume that the reaction
H2O(g) + CO(g)
H2(g) + CO2(g)
occurs in an ideal mixture of ideal gases. At 700 K, Kp = 5.10. What is G˚ at this
temperature?
A.
B.
C.
D.
E.
-9.48 kJ/mol
-4.12 kJ/mol
0 kJ/mol
9.48 kJ/mol
-29.7 kJ/mol
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4. If H = -150 kJ/mol for a given process, then it
A.
B.
C.
D.
E.
needs a catalyst
does not need a catalyst
occurs slowly
is endothermic
is exothermic
5. For a certain hypothetical reaction at 300K, H° = 100 kJ/mol and S° = 0.500 kJ/K.
Calculate G° for this reaction.
(a)
(b)
(c)
(d)
(e)
250 kJ/mol
150 kJ/mol
50 kJ/mol
-50 kJ/mol
-250 kJ/mol
6. What is the minimum temperature required for the spontaneous conversion of CCl4(g)
when H° is 573 kJ/mol and S° is 1640 J/(mol K)
(a)
(b)
(c)
(d)
(e)
76° C
89° C
189° C
215° C
349° C
7. For the reaction: 3 C(s) + 4 H2(g) <======> C3H8(g)
S° = -29 J/(mol K)
H° = -103.8 kJ/mol
Calculate the equilibrium constant at 25° C for the reaction above.
(a)
(b)
(c)
(d)
(e)
1.0
1.4 x 104
4.2 x 1016
3.7 x 1019
2.1 x 1032
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8. The following reaction has G˚ = 42.6 kJ/mol at 25˚C. What is Ka for the acid HB?
HB(aq) + H2O(l)
A.
B.
C.
D.
E.
B-(aq) + H3O+(aq)
-17.2
3.41  10-8
1.13  10-5
1.63
14.0
9. Consider the following reactions I and II:
I.
II.
3Fe(s) + 2O2(g)   Fe3O4(s)
C(graphite) + O2(g)   CO2(g)
Go = -1014.2 kJ
Go = -394.4 kJ
What is the change in free energy, G, (in kJ) for reaction III shown below?
III.
Fe3O4(s) + 2C(graphite)   3Fe(s) + 2CO2(g)
a) +1802.4
b) +619.8
c) +225.4
d) +788.2
e) -788.2
10. Cathode protection results when
A.
B.
C.
D.
E.
iron is made amphoteric
iron is amalgamated with mercury
iron is tin-plated for use as a tin can
iron is painted to protect it from corrosion
iron is attached to a more active metal
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11. The measured voltage for the reaction with the indicated concentrations is 1.50 V.
Calculate E˚.
Cr (s) + 3 Ag+ (aq, 0.10 M)  Ag (s) + Cr3+ (aq, 0.30 M)
A.
B.
C.
D.
E.
1.35
1.40
1.45
1.55
1.65
12. When the basic solution redox equation, MnO4- + CN- MnO2 + CNO-, is
properly balanced, the coefficients of the reactants and products shown are, in order,
A.
B.
C.
D.
E.
1, 1, 1, 1
1, 2, 1, 2
2, 1, 2, 1
1, 3, 1, 3
2, 3, 2, 3
13. An oxidation-reduction reaction is one that involves at least one change of
A.
B.
C.
D.
E.
formal charge.
oxidation potential.
oxidation state.
atomic number.
polarity.
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14. If nothing happens when an electrolytic cell is assembled, which of the following are
possible explanations?
1. The salt bridge is broken.
2. One of the electrodes is corroded.
3. A stronger battery is needed.
A.
B.
C.
D.
E.
1 only
2 only
3 only
1 and 2
1, 2, and 3
15. A two-compartment electrochemical cell has a silver electrode immersed in 1.0 M
AgNO3 in one compartment, and a zinc electrode immersed in 1.0 M Zn(NO3)2 in the
other. A salt bridge connects the two compartments, and the electrodes are connected
through a voltmeter. The standard reduction potentials are
Ag+ + e-  Ag
Zn2+ + 2e-  Zn
E˚ = +0.80 V
E˚ = -0.76 V
Which of the following statements is false?
A.
B.
C.
D.
E.
The silver electrode is the cathode.
The standard cell potential for this cell is 1.56 V.
The zinc electrode will lose mass, and the silver electrode will gain mass.
Electrons in the external circuit will flow from zinc to silver.
Increasing [Zn2+] will increase the cell voltage.
16. If a constant current of 5.0 amperes is passed through a cell containing Cr3+ for 1.0
hour, how many grams of Cr will plate onto the cathode?
A.
B.
C.
D.
E.
0.054 g
1.5 g
3.2 g
9.7 g
93 g
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17. Electrolysis refers to an electrochemical reaction that is
A.
B.
C.
D.
E.
exothermic.
spontaneous.
nonspontaneous, but forced to proceed.
voltaic.
oxidation-reduction.
18. Which of the following reactions is a redox reaction?
I.
K2CrO4 + BaCl2  BaCrO4 + 2KCl
II.
Pb22+ + 2Br-  PbBr
III.
Cu + S  CuS
A.
B.
C.
D.
E.
only I
only II
only III
I and II
all three (I, II and III)
19. Use the standard reduction potentials:
Cu2+  Cu+
+0.16 V
I2  I+0.54 V
Calculate the value of E° (in V) for a cell in which the overall reaction is
2Cu+ + I2  2Cu2+ + 2IA.
B.
C.
D.
E.
0.38 V
–0.38 V
0.68 V
–0.68V
0.83 V
20. What process occurs at an anode?
A.
B.
C.
D.
E.
oxidation
reduction
oxidation and/or reduction
neither oxidation nor reduction
none of the above
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21. If a piece of tin and a piece of copper were submerged in a solution containing SnSO4
and CuCl2, what would happen?
Cu+2(aq) + 2e-  Cu(s)
E° = 0.337 V
+2
Sn (aq) + 2e-  Sn(s)
E° = -0.136 V
A.
B.
C.
D.
E.
The tin electrode would gain weight and the copper electrode lose weight.
The tin electrode would gain weight and the copper electrode gain weight.
The tin electrode would lose weight and the copper electrode lose weight.
The tin electrode would lose weight and the copper electrode gain weight.
Nothing would happen.
22. In the reaction
2 Al(s) + 3 Cu2+(aq) ------> 2 Al3+(aq) + 3 Cu(s)
the aluminum
(a)
(b)
(c)
(d)
(e)
gains protons
gains electrons
loses protons
loses electrons
none of the above
23. How many electrons are involved in the following reaction?
Cl2 + 2 Br- --------> 2 Cl- + Br2
(a)
(b)
(c)
(d)
(e)
6
2
1
4
3
24. Which of the following statements, referring to the reaction below, is correct?
N2(g) + 3Cl2(g)  2NCl3(g)
A)
B)
C)
D)
E)
The N2 is an oxidizing agent and the Cl2 is a reducing agent.
The Cl2 is an oxidizing agent and the N2 is a reducing agent.
Both N2 and Cl2 are oxidizing agents.
Both N2 and Cl2 are reducing agents.
No oxidation or reduction occurs in this reaction.
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Extra Credit: Show all work for credit
The standard emf for the cell using the overall cell reaction below is +2.20 volts.
2Al (s) + 3I2 (s)  2Al+3 (aq) + 6I- (aq)
The emf generated by the cell when [Al+3] = 4.5 x 10-3 M and [I-] = 0.15M is _____volts?
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