CHEM 102
Major Exam II (082)



1.
Entropy decreases during
A.
boiling
B.
sublimation
C.
vaporization
D.
condensation
E.
decomposition


2.
The values of ΔGfº of CO2(g) , H2O(l) and C2H2(g) are –394.4, –237.2 and 209.2 kJ-mol–1, respectively. The free energy of combustion of two moles of C2H2(g) is
A.
–4720 kJ
B.
–2470 kJ
C.
–3740 kJ
D.
–1580 kJ
E.
–1247 kJ


3.
For a certain process at 355 K, ΔG = -11.7 kJ and ΔH = -9.2 kJ. Therefore, ΔS for the process is
A.
0
B.
7.0 J/K mol
C.
–7.0 J/K mol
D.
–25.9 J/K mol
E.
25.9 J/K mol


4.
The statement that is always true is
A.
Spontaneous processes increase system entropy.
B.
Spontaneous processes decrease system entropy.
C.
Spontaneous processes can decrease or increase system entropy.
D.
Spontaneous processes lead to no change in system entropy.
E.
Spontaneous processes don't depend on the system temperature.


5.
Consider the following process:
Given that S° for mercury at 25°C = 77.4 J-K–1-mol–1 , S° for mercury at the boiling point = 174.7 J-K–1-mol–1 , ΔH° = 60.78 kJ-mol–1, calculate the boiling point of mercury
A.
352 °C
B.
256 °C
C.
456 °C
D.
356 °C
E.
126 °C


6.
A 0.1 M solution of a weak acid, HX, has a pH of 5.83 at 25 °C, what is ΔG° for the acid's dissociation reaction at 25 °C?
A.
61 kJ
B.
126 kJ
C.
2.1 kJ
D.
70 kJ
E.
254 kJ


7.
The species _____ is the best to oxidize water to oxygen under standard state conditions.
A.
Cl–(aq)
B.
Cu2+(aq)
C.
Pb2+(aq)
D.
Cl2(g)
E.
Fe2+(aq)


8.
When an aqueous solution of NaCl is electrolyzed,
A.
Na(s) and Cl2(g) are produced at the cathode and anode, respectively.
B.
Na(s) and Cl2(g) are produced at the anode and cathode, respectively.
C.
H2(g) is produced at the cathode
D.
O2(g) is produced at the anode
E.
Cl- and H2O will be oxidized simultaneously at the anode.


9.
The emf of the cell consisting of the Zn/Zn2+ half-cell with [Zn2+] = 0.045 M and a hydrogen electrode with P(H2) = 2 atm and [H+]=1.8 M is
A.
0.54 V
B.
0.84 V
C.
0.81 V
D.
0.64 V
E.
0.14 V


10.
The passage of 0.750 A for 25.0 min deposited 0.369 g of a divalent unknown metal. The metal is,
A.
Cu
B.
Eu
C.
Hg
D.
Mn
E.
Fe


11.
The equilibrium constant for the following reaction is 2.69 × 1012 at 25°C.
The value of E° for this reaction is
A.
0.215 V
B.
0.368 V
C.
0.162 V
D.
1.81V
E.
1.10 V


12.
The standard emf of a galvanic cell containing standard cadmium and magnesium electrodes is
A.
1.97 V
B.
1.18 V
C.
2.37 V
D.
2.02 V
E.
0.67 V


13.
The quantity that will not change when a cell reaction is multiplied by two is
A.
ΔG
B.
K
C.
E
D.
ΔG°
E.
ΔH


14.
Species 'X' in the following equation is a(an)
A.
proton
B.
positron
C.
neutron
D.
electron
E.
alpha particle


15.
The half-life of Tl-206 decay to Pb-206 is 4.20 minutes. Starting with 5.00 × 1022 atoms of Tl-206, the number of Tl atoms left after 42.0 minutes is
A.
4.89 × 1019
B.
2.12 × 1021
C.
9.72 × 1017
D.
7.50 × 1015
E.
1.50 × 1011


16.
The material in a nuclear reactor that reduces the number of neutrons is called a
A.
reducer
B.
moderator
C.
control rod
D.
reflector
E.
oxidizer


17.
Uranium-235 on fission by slow neutrons yields barium-141, 3 neutrons and
A.
krypton
B.
xenon
C.
radon
D.
cesium
E.
helium


18.
Given that the masses of proton and neutron are 1.0078 and 1.0087 amu, respectively. What is the nuclear binding energy of 10B ( atomic mass = 10.0129 amu) is,
[Note: 1 amu = 1.66 × 10-27 kg]
A.
1.040 × 10–12 J/nucleon
B.
1.199 × 10–12 J/nucleon
C.
1.690 × 10–12 J/nucleon
D.
1.810 × 10–12 J/nucleon
E.
1.410 × 10–12 J/nucleon


19.
A sample of moon rock contains 18% 40K and 82% 40Ar by mass. 40K decays to 40Ar with a half-life of 1.2 × 109 yr. The age of the rock is
A.
2 × 107 yr
B.
4 × 108 yr
C.
3 × 109 yr
D.
7 × 1010 yr
E.
6 × 105 yr


20.
Nuclear belt stability is based on the _____ ratio.
A.
B.
C.
D.
E.


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