Name: __________________________ Date: _____________
Columbia UNI:
Instructions: You will have 85 minutes to answer the questions on this exam. It consists
of 20 multiple choice questions, each worth 1 point. You will be permitted to use a
calculator and the attached reference sheets. GOOD LUCK!
1. When the following reaction is balanced in acidic solution, what is the coefficient of
water?
Zn(s) + NO3–(aq)  Zn2+(aq) + NH4+(aq)
A) 1 (11 using H3O+)
B) 2 (12 using H3O+)
C) 3 (13 using H3O+)
D) 4 (14 using H3O+)
E) none of these
2. For the reaction of sodium bromide with chlorine gas to form sodium chloride and
bromine, what are the appropriate half-reactions and the standard cell potential? (ox =
oxidation and re = reduction)
A) ox: Cl2 + 2e–  2Cl–; re: 2Br–  Br2 + 2e–; Eo = -0.17 V
B) ox: 2Br–  Br2 + 2e–; re: Cl2 + 2e–  2Cl–; Eo = 0.17 V
C) ox: Cl + e–  Cl–;
re: Br  Br– + e–;
Eo = 0.17 V
D) ox: Br + 2e–  Br2–;
re: 2Cl–  Cl2 + 2e–; Eo = -0.17 V
+
–
E) ox: 2Na + 2e  2Na; re: 2Cl–  Cl2 + 2e–;
Eo = -4.07 V
3. In the balanced equation for the following redox equation, what is the sum of the
coefficients?
Fe3+ + I–  Fe2+ + I2
A) 4
B) 5
C) 6
D) 7
E) 8
4. Which one of the following statements is false?
A) The change in internal energy, E, for a process is equal to the amount of heat
absorbed at constant volume, qv.
B) The change in enthalpy, H, for a process is equal to the amount of heat absorbed
at constant pressure, qp.
C) A bomb calorimeter measures H directly.
D) If qp for a process is negative, the process is exothermic.
E) The freezing of water is an example of an exothermic reaction.
5. The total volume of hydrogen gas needed to fill the Hindenburg was 2.00  108 L at
1.00 atm and 25.0°C. How much energy was evolved when it burned?
H2(g) + (1/2)O2(g)  H2O(l), H = –286 kJ
A) 3.5  1011 kJ
B) 8.18  106 kJ
C) 2.86  104 kJ
D) 2.34  109 kJ
E) 5.72  1010 kJ
Use the following to answer questions 6-7:
Consider a process carried out on 1.00 mol of a monatomic ideal gas by the following
two different pathways. The first pathway is A (3.00 atm, 20.0 L) to C (1.00 atm, 20.0 L)
to D (1.00 atm, 50.0 L); and the second pathway is A (3.00 atm, 20.0 L) to B (3.00 atm,
50.0 L) to D (1.00 atm, 50.0 L). In each case, the gas is taken from state A to state D.
6. Calculate wAB.
A) -90 L•atm
B) 90 L•atm
C) -30 L•atm
D) 30 L•atm
E) 0
7. Calculate qAC.
A) 60 L•atm
B) -60 L•atm
C) 100 L•atm
D) -100 L•atm
E) none of these
Use the following to answer question 8:
Two samples of a monatomic ideal gas are in separate containers at the same conditions
of pressure, volume, and temperature (V = 1.00 L and P = 1.00 atm). Both samples
undergo changes in conditions and finish with V = 2.00 L and P = 2.00 atm. However, in
the first sample, the volume is changed to 2.0 L while the pressure is kept constant, and
then the pressure is increased to 2.00 atm while the volume remains constant. In the
second sample, the opposite is done. The pressure is increased first, with constant
volume, and then the volume is increased under constant pressure.
8. Calculate the difference in E between the first sample and the second sample.
A) 0
B) 1.00 L•atm
C) 2.00 L•atm
D) 4.50 L•atm
E) none of these
9. For the reaction
AgI(s) + (1/2)Br2(g)  AgBr(s) + (1/2)I2(s), H° = –54.0 kJ
H°f for AgBr(s) = –100.4 kJ/mol
H°f for Br2(g) = +30.9 kJ/mol
The value of H°f for AgI(s) is
A) –123.5 kJ/mol
B) +77.3 kJ/mol
C) +61.8 kJ/mol
D) –77.3 kJ/mol
E) –61.8 kJ/mol
10. One mole of an ideal gas is compressed isothermally at 607.4 K from 5.60 atm to 8.90
atm. If the process is carried out in two irreversible steps (intermediate step at P = 7.00
atm), calculate S.
A) 2.34 J/K
B) -2.34 J/K
C) -3.85 J/K
D) 3.85 J/K
E) 0 J/K
11. An ideal gas expands isothermally and irreversibly. What can you say about w and q,
respectively?
A) w is less than zero and q is greater than zero.
B) w is equal to zero and q is equal to zero.
C) w is greater than zero and q is less than zero.
D) w is less than zero and q is less than zero.
E) More information is needed.
12. Substance X has a heat of vaporization of 55.4 kJ/mol at its normal boiling point
(423°C). For the process X(l)  X(g) at 1 atm and 423°C, calculate the value of Ssurr.
A) 0
B) 79.6 J/K•mol
C) 103 J/K•mol
D) -79.6 J/K•mol
E) -103 J/K•mol
13. A machine employs the isothermal expansion of 1 mol of an ideal gas from 4.50 L to
15.0 L. At 25°C, the machine performs 3.00 kJ of work. What percent of the maximum
possible work is the machine producing?
A) 4.50%
B) 50.3%
C) 0.60%
D) 15.0%
E) This amount of work cannot be correct.
14. Calculate G for the isothermal compression of 1 mol of an ideal monatomic gas from
2.3 atm to 6.0 atm at 28°C.
A) 2.4  103 J
B) 1.8  103 J
C) -2.4  103 J
D) -1.8  103 J
E) 3.6 103 J
15. The equilibrium constant Kp for the dissociation reaction of Cl2
Cl2(g)
2Cl(g)
was measured as a function of temperature (in K). A graph of ln Kp versus 1/T for this
reaction gives a straight line with a slope of –1.352  104 and an intercept of 14.51.
What is the value of S for this dissociation reaction? Hint: Think of the relationship
between G, H, S and Kp.
A) 26.81 J/K•mol
B) 112.0 J/K•mol
C) 120.6 J/K•mol
D) 53.14 J/K•mol
E) none of these
16. Consider the reaction
2N2O5(g)
4NO2(g) + O2(g)
at 25°C, for which the following data are relevant:
S° (J/K•mol)
H°f (kJ/mol)
N2O5
11.29
355.3
NO2
33.15
239.9
O2
0
204.8
The reaction is allowed to proceed until all substances involved have reached their
equilibrium concentrations. Under those conditions, what is G for the reaction?
A) –135 kJ
B) 98.7 kJ
C) –25.2 kJ
D) –11.2 kJ
E) 0
17. Consider a galvanic cell that utilizes the following reaction (unbalanced):
(AuCl4)–(aq) + Cu(s)  Au(s) + Cl–(aq) + Cu2+(aq)
Determine the standard cell potential. Hint: Think of what the oxidation number of Au
is in (AuCl4)-.
A)
B)
C)
D)
E)
1.06 V
1.74 V
1.35 V
-1.35 V
1.84 V
18. Consider the hydrogen–oxygen fuel cell where
H2(g) + ½ O2(g)
H2O(l) G° = –237.18 kJ/mol H2
Which of the following statements is(are) true?
I.
At standard conditions, the maximum work the fuel cell could do on the
surroundings is 237.18 kJ/mol.
II.
At standard conditions, the cell potential is 1.23 V.
III. More energy is dissipated as waste heat in the fuel cell than in the reversible
pathway.
A) I
B) II
C) III
D) I, II, and III
E) None of the statements is true.
19. An antique automobile bumper is to be chrome plated. The bumper, which is dipped
into an acidic Cr2O72– solution, serves as a cathode of an electrolytic cell. If the current
is 35.2 amperes, how long will it take to deposit 2.46  102 g of Cr(s) onto the bumper?
Hint: Determine the oxidation number of Cr in Cr2O72- and balance the redox reaction.
A)
B)
C)
D)
E)
43.2 h
21.6 h
36.0 min
37.3 h
14.4 h
20. Refer to the galvanic cell below (the contents of each half-cell are written beneath each
compartment).
The standard reduction potentials are as follows:
MnO4 + 8H+ + 5e–  Mn2+ + 4H2O
E = 1.51 V
–
Cr2O72– +14H+ + 6e–  2 Cr3+ +7H2O
E = 1.33 V
What is the value of Q, the reaction quotient, for this cell reaction?
A) 6.7  1040
B) 1.5  10–41
C) 1.5  10–4
D) 6.7  103
S1404 General Chemistry II
Prof. Savizky
Useful Information
Universal Gas Constant:
Temperature:
Definitions:
Equations of State:
R= 8.314 J/mol*K
= 1.987 cal/mol*K
= 0.0821 L*atm/mol*K
K  C  273.15
 U 
cv  

 T  v
 H 
cp  

 T  P
Perfect gas
van der Waals
Virial
Perfect gases:
Monatomic:
U  U (T )
H  H (T )
c p  cv  nR
Pv  RT
a

 P  2 v  b   RT
v 

Pv
B C
Z
1  2 
RT
v v
3
R
2
5
cp  R
2
For each atom add a value of R (linear) or 3/2 R (non-linear).
cv 
Thermodynamics:
1st Law
du  dq  dw
dU  dQ  dW
u  q  w
U  Q  W
2 Law
dQrev
dS 
T
Stot  0( spon. process )
rd
3 Law
lim
S 0
T 0
nd
State functions:
H  U  PV
A  U  TS
G  H  TS
Work:
General (PV work only):
Isothermal (perfect gas):
Isobaric:
Internal Energy:
Constant volume, cv:
Enthalpy:
Constant pressure, cp:
Adiabatic Processes:
dWrev   PdV
V
P
W  nRT ln 2  nRT ln 2
V1
P1
W   Pext V
U  ncv T
H  nc p T


P1V1  P2V2 ,   c p / cv
Constant cp, cv:
 T2   V1 
    
 T1   V2 
nR cv
 T2   P1 
    
 T1   P2 
 nR c p
Entropy:
dQ
T
General:
dS 
Isothermal (perfect gas):
S  nR ln
V2
V1
T2
T1
T
S  ncv ln 2
T1
H trans
S 
T
S  nc p ln
Isobaric (constant cp):
Isochoric (constant cv):
Phase Transition:
Free Energy:
P2
G   VdP
Isothermal:
P1
Constant volume:
G  VP
Perfect gas:
G  nRT ln
P2
P1
 G 
Grxn  

   P ,T
Reactions:
o
Grxn  Grxn
 RT ln Q
Q   [molarity ]i i
At equilibrium:
Grxn   RT ln K
K   [molarity ]i i
van’t Hoff:
o
d ln K H rxn

dT
RT 2
o
H rxn
d ln K

d (1 / T )
R
ln
H rxn
K2

K1
R
1 1
  
 T2 T1 
Electrochemistry:
, F = 96485 C/mol
Nernst equation:
At 25oC:
Page 2
Page 3
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Page 5
Answer Key
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
12.
13.
14.
15.
16.
17.
18.
19.
20.
C
B
D
C
D
A
B
A
E
C
A
D
E
A
C
E
A
D
B
B
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