R = 8.314 × 10–3 kJ·mol–1·K–1
F = 96485 C·mol–1
 
ΔSsurr = -qsys/T
(at const. T)
qsys = ΔHsys
(at const. P)
ΔGr° = ΔHr° - TΔSr°          
ΔSr° = Σ n Sm°(prod) – Σ n Sm°(react)
ΔHr° = Σ n ΔHf°(prod) – Σ n ΔHf°(react)
ΔGr° = – RT lnK
ΔGr = ΔGr° + RT lnQ
E° = (0.0257/n) lnK
(at 298 K)
E = E° – (0.0257/n) lnQ
(at 298 K)
ΔGr° = – nFEcell°
n = (I t)/F
 



1.
Which of the following should have the greatest molar entropy at 298 K?
A.
CH4(g)
B.
H2O(l)
C.
NaCl(s)
D.
N2O4(g)
E.
H2(g)


2.
Which relationship or statement best describes ΔS° for the following reaction?
O3(g)   +    NO(g)   →   O2(g)   +   NO2(g)
A.
ΔS° ≈ 0
B.
ΔS° < 0
C.
ΔS° > 0
D.
ΔS° = ΔH°/T
E.
More information is needed to make a reasonable prediction.


3.
Which relationship or statement best describes ΔS° for the following reaction?
K2SO4(s)   →   2K+(aq)   +   SO42-(aq)
A.
ΔS° ≈ 0
B.
ΔS° < 0
C.
ΔS° > 0
D.
ΔS° = ΔH°/T
E.
More information is needed to make a reasonable prediction.


4.
Calculate ΔS°for the reaction
4Cr(s)   +   3O2(g)   →   2Cr2O3(s)
Substance
Cr(s)
O2(g)
Cr2O3(s)
S°(J/K⋅mol)
23.77
205.138
81.2
 
A.
-548.1 J/K
B.
-147.7 J/K
C.
147.7 J/K
D.
310.1 J/K
E.
548.1 J/K


5.
For a chemical reaction to be spontaneous only at high temperatures, which of the following conditions must be met?
A.
ΔS° > 0, ΔH° > 0
B.
ΔS° > 0, ΔH° < 0
C.
ΔS° < 0, ΔH° < 0
D.
ΔS° < 0, ΔH° > 0
E.
ΔG° > 0


6.
Calculate ΔG° for the reaction of ammonia with fluorine at 298 K.
2NH3(g)   +   5F2(g) →   N2F4(g)   +   6HF(g)
Substance
NH3(g)
F2(g)
N2F4(g)
HF(g)
ΔG°f   (kJ/mol at 298K)
-16.4
0
79.9
-275.4
 
A.
179.1 kJ
B.
-179.1 kJ
C.
1539.7 kJ
D.
-1539.7 kJ
E.
none of the above


7.
Nitric oxide reacts with chlorine to form NOCl. The data refer to 298 K.
2NO(g)   +   Cl2(g)   →   2NOCl(g)
Substance
NO(g)
Cl2(g)
NOCl(g)
ΔH°f   (kJ/mol)
90.29
0
51.71
ΔG°f   (kJ/mol)
86.60
0
66.07
S°(J/K⋅mol)
210.65
223.0
261.6
What is the value of ΔG° for this reaction at 550 K?
A.
-143.76 kJ
B.
-78.78 kJ
C.
-22.24 kJ
D.
-10.56 kJ
E.
66600 kJ


8.
The temperature at which the following process reaches equilibrium at 1.0 atm is the normal boiling point of hydrogen peroxide.
H2O2(l)   ↔   H2O2(g)  
Use the following thermodynamic information at 298 K to determine this temperature.
Substance
H2O2(l)
H2O2(g)
ΔH°f   (kJ/mol)
-187.7
-136.3
S° (J/K⋅mol)
109.6
232.7
 
A.
120 Κ
B.
418 Κ
C.
196 Κ
D.
144 Κ
E.
585 Κ


9.
The formation constant for the reaction
Ag+(aq)   +   2NH3(aq)   ↔   Ag(NH3)2+(aq)
is Kf = 1.7 × 107 at 25°C. What is ΔG° at this temperature?
A.
-1.5 kJ
B.
-3.5 kJ
C.
-18 kJ
D.
-23 kJ
E.
-41 kJ


10.
When the following redox equation is balanced with the smallest whole number coefficients, the coefficient for zinc will be _____.
Zn(s)   +   ReO4-(aq)   →   Re(s)   +   Zn2+(aq)    (acidic solution)
A.
2
B.
7
C.
8
D.
16
E.
none of the above


11.
Which of the following statements about voltaic and electrolytic cells is correct?
A.
The electrons in the external wire flow from cathode to anode in both types of cell.
B.
Oxidation occurs at the cathode only in a voltaic cell.
C.
The free energy change, ΔG, is negative for an electrolytic cell.
D.
The cathode is labeled as positive (+) in a voltaic cell but negative (–) in an electrolytic cell.
E.
Reduction occurs at the anode in an electrolytic cell.


12.
A voltaic cell prepared using aluminum and nickel has the following cell notation.
Al(s) | Al3+(aq) || Ni2+(aq) | Ni(s)
Which of the following represents the correctly balanced spontaneous reaction equation for the cell?
A.
Ni2+(aq)   +   Al(s)   →   Al3+(aq)   +   Ni(s)
B.
3Ni2+(aq)   +   2Al(s)   →   2Al3+(aq)   +   3Ni(s)
C.
Ni(s)   +   Al3+(aq)   →   Ni2+(aq)   +   Al(s)
D.
3Ni(s)   +   2Al3+(aq)   →   3Ni2+(aq)   +   2Al(s)
E.
none of the above


13.
What is the E°cell for the cell represented by the combination of the following half-reactions?
2Hg2+(aq)   +   2e- ↔   Hg22+(aq)    E°= 0.92 V
Cr3+ (aq)   +   3e-      ↔   Cr(s)    E°= -0.74 V
A.
-0.18 V
B.
0.18 V
C.
1.28 V
D.
1.66 V
E.
2.12 V


14.
Examine the following half-reactions and select the strongest oxidizing agent among the species listed.
Cr2+(aq) +   2e- ↔   Cr(s)    E° = -0.913 V
Fe2+(aq)   +   2e- ↔   Fe(s)    E° = -0.447 V
Sr2+(aq)   +   2e-   ↔   Sr(s)    E° = -2.89 V
Co2+(aq)   +   2e- ↔   Co(s)    E° = -0.28 V
A.
Cr2+(aq)
B.
Fe(s)
C.
Fe2+(aq)
D.
Sr2+(aq)
E.
Co2+(aq)


15.
Given:
Co3+(aq)   +   e-    ↔   Co2+(aq)                E° = 1.82 V
MnO4-(aq)   +   2H2O(l)   +   3e-     ↔   MnO2(s)   +   4OH-(aq)    E° = 0.59 V
Calculate E°cell for the following reaction and indicate whether the reaction is spontaneous or nonspontaneous:
MnO4-(aq)   +   2H2O(l)   +   3Co2+(aq)    →    MnO2(s)   +   3Co3+(aq)   +   4OH-(aq)
A.
E°cell = -1.23 V, spontaneous
B.
E°cell = -1.23 V, nonspontaneous
C.
E°cell = 1.23 V, spontaneous
D.
E°cell = 1.23 V, nonspontaneous
E.
E°cell = -0.05 V, nonspontaneous


16.
What is the value of the equilibrium constant for the cell reaction below at 25°C? E°cell = 0.30 V
Sn2+(aq)   +   Fe(s)   ↔   Sn(s)   +   Fe2+(aq)
A.
1.2 × 105
B.
1.4 × 1010
C.
8.6 × 10-6
D.
7.1 × 10-11
E.
2.3 × 1023


17.
A voltaic cell consists of a Cd/Cd2+ electrode (E° = -0.40 V) and a Fe/Fe2+ electrode (E° = -0.44 V). If [Fe2+] = 0.15 M and [Cd2+] = 1.0 M, calculate Ecell at 25°C.  
A.
0.06 V
B.
0.04 V
C.
0.00 V
D.
-0.04 V
E.
-0.06 V


18.
Which, if any, of the following metals would be capable of acting as a sacrificial anode when used to protect iron? E°Fe = -0.44 V; all E° values refer to the M2+/M half-cell reactions.
A.
copper, Cu, E° = 0.15 V
B.
cobalt, Co, E° = -0.28 V
C.
chromium, Cr, E° = -0.74 V
D.
tin, Sn, E° = -0.14 V
E.
None of these metals would be capable of acting as a sacrificial anode with iron.


19.
Which of the following elements can be isolated by electrolysis of the aqueous salt shown?
A.
phosphorus from K3PO4(aq)
B.
sodium from NaBr(aq)
C.
aluminum from AlCl3(aq)
D.
fluorine from KF(aq)
E.
iodine from NaI(aq)


20.
What mass of silver (molar mass 107.9 g/mol) will be formed when 15.0 A are passed through molten AgCl for 25.0 minutes?
A.
0.419 g
B.
6.29 g
C.
12.6 g
D.
25.2 g
E.
33.4 g


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