Download CHEM 112 – Exam 4 (2011) – General Chemistry (Lori

Chemistry 112
Name
_______________________
Final Exam Form A
Section
_______________________
June 27, 2011
eMail
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IMPORTANT: On the scantron (answer sheet), you MUST clearly fill your name, your
student number, section number, and test form (white cover = test form A; yellow
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There are 40 questions on this exam. Check that you have done all of the problems
and filled in the first 40 bubbles on the scantron. The maximum score on this exam is 40
points. Your score will be reported in percent (max 100%).
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Calculators with text-programmable memory are not allowed.
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CHEMISTRY 112
FINAL EXAM
JUNE 27, 2011
FORM A
----------------------------------------------------------------------------------------------------------------1. Which one of the following transition metal complexes is paramagnetic? (Hint: Cl–
and H2O are weak field ligands, CN– and NH3 are strong field ligands.)
A.
TiCl4
B.
Zn(H2O)62+
C.
Zn(NH3)62+
D.
Fe(CN)64–
E.
Fe(H2O)62+
-----------------------------------------------------------------------------------------------------------2. What is the coordination number and the charge on the metal in the following
complex? [Pt(en)3](ClO4)4
charge
Coordination
number
A.
+2
6
B.
+2
3
C.
+4
6
D.
+4
3
E.
+2
4
----------------------------------------------------------------------------------------------------------------3. The coordination number for the metal in all of the complexes below is 6 except for
one. Which one does NOT have a coordination number of 6?
A.
K [Co(EDTA)]
B.
K2 [Ni(en)3]
C.
Na [Ru(H2O)2(C2O4)2]
D.
[Cu(H2O)2(en)] Cl2
E.
[Co(NH3)5NO2] Cl2
-----------------------------------------------------------------------------------------------------------------
----------------------------------------------------------------------------------------------------------------4. Which one of the following is not likely to exist?
A.
BCl3
B.
CCl4
C.
NCl3
D.
NCl5
E.
SF6
----------------------------------------------------------------------------------------------------------------5. Which of the following is a characteristic change on moving from left to right within a
period in the periodic table?
1.
The size of the element increases
2.
The electronegativity of the element increases
3.
The element becomes more likely to exhibit a positive
oxidation state in its compounds
A.
1, 2, and 3
B.
1 and 2
C.
2 and 3
D.
1 and 3
E.
2 only
----------------------------------------------------------------------------------------------------------------6. Which of the following compounds contains hydrogen in the –1 oxidation state?
A.
LiH
B.
H2S
C.
NH3
D.
SiH4
E.
H2
-----------------------------------------------------------------------------------------------------------------
--------------------------------------------------------------------------------------------------------------------7. Which one of the following solids is incorrectly classified?
A.
Mg
metallic
B.
S8
molecular
C.
SiO2 network covalent
D.
HBr
ionic
E.
Br2
molecular
--------------------------------------------------------------------------------------------------------------------8. What are the units of the rate constant for a second order reaction?
A.
M/s
B.
M1s1
C.
1/s
D.
1/M
E.
s/M2
--------------------------------------------------------------------------------------------------------------------9. Given a mechanism, what is the intermediate?
F2 (g) + NO2 (g) → NO2F (g) + F (g)
slow
NO2 (g) + F (g) → NO2F (g)
fast
A.
NO2 (g)
B.
F (g)
C.
NO2F (g)
D.
F (g) and NO2F (g)
E.
There is no intermediate for this reaction
--------------------------------------------------------------------------------------------------------------------10. When 235U is bombarded with one neutron, one set of products are three neutrons,
91
Kr, and _________
A.
139Ba
B.
142Ba
C.
139Ce
D.
139Xe
E.
142I
---------------------------------------------------------------------------------------------------------------------
--------------------------------------------------------------------------------------------------------------------11.
A 0.25M solution of a weak acid, HX, has a pH of 3.75. What is the acid
dissociation constant?
A.
1.5  10−2
B.
1.8  10−4
C.
1.3  10−7
D.
2.0  10−8
E.
3.2  10−10
--------------------------------------------------------------------------------------------------------------------12. Which reaction has a positive standard entropy change, S?
A.
2 H2 (g) + O2 (g)  2 H2O (g)
B.
4 Fe (s) + 3 O2 (g)  2 Fe2O3 (s)
C.
Br2 () + C18H36 (s)  C18H36Br2 (s)
D.
CO2 (g)  CO2 (s)
E.
H2O ()  H+(aq) + OH−(aq)
--------------------------------------------------------------------------------------------------------------------13. The Ksp for Zn(OH)2 is 3.0  10−16. What is the solubility of Zn(OH)2 in a solution
with pH of 7.5?
A.
3.0  10−3 M
B.
6.7  10−6 M
C.
4.2  10−6 M
D.
1.7  10−8 M
E.
3.0  10−16 M
---------------------------------------------------------------------------------------------------------------------
--------------------------------------------------------------------------------------------------------------------14. Which one of the following compounds will have an increased solubility if the pH of
a saturated solution of the compound is lowered?
A.
AgCl
B.
AgI
C.
PbSO4
D.
PbCl2
E.
PbCO3
--------------------------------------------------------------------------------------------------------------------15. Which one of the following is a redox reaction?
A.
NaOH + HCl  NaCl + H2O
B.
H2O2 + 2 HBr  2 H2O + Br2
C.
AgNO3 + NaCl  AgCl + NaNO3
D.
NH4Cl + H2O  NH4+ + Cl
E.
None of the above is a redox reaction
--------------------------------------------------------------------------------------------------------------------16. An electrochemical cell is made with one Zn electrode and one Cu electrode, in
1.0 M Zn(NO3)2 and 1.0 M Cu(NO3)2 solutions respectively connected by a salt
bridge. A current of 0.1 A flows in the spontaneous direction. If the initial mass of
the Cu electrode is 1.000 g, what is its mass at the end of 20 minutes?
A.
1.089 g
B.
1.040 g
C.
0.911 g
D.
0.905 g
E.
0.863 g
---------------------------------------------------------------------------------------------------------------------
--------------------------------------------------------------------------------------------------------------------17. What is the coefficient of Cl2 when the following equation is completed and
balanced?
Cr2O72−aq) + Cl−(aq)  Cr3+ (aq) + Cl2 (g)
A.
1
B.
3
C.
5
D.
6
E.
8
(acidic solution)
--------------------------------------------------------------------------------------------------------------------18. The entropy of vaporization (Svap) for benzene is 96.4 J/K(mol). The enthalpy of
vaporization (Hvap) is 33.9 kJ/mol. What is the boiling point in C for benzene?
A.
79C
B.
352C
C.
0C
D.
100C
E.
35C
----------------------------------------------------------------------------------------------------------------19. The water ligands on [Cu(H2O)4]2+ can be replaced with other ligands using ligand
exchange reactions. Consider the following complexes that undergo ligand
exchange reactions to displace two water molecules. Which complex would you
expect to have the largest formation constant? (en = ethylenediamine)
A.
[Cu(H2O)2Cl2]2+
B.
[Cu(H2O)2Br2]2+
C.
[Cu(H2O)2(NO2)2]2+
D.
[Cu(H2O)2(NH3)2]2+
E.
[Cu(H2O)2(en)]2+
-----------------------------------------------------------------------------------------------------------------
----------------------------------------------------------------------------------------------------------------20. Which of the following aqueous solutions will have the same concentration of ions
as a 0.1M solution of MgCl2 ?
A.
0.1 M K3[Co(CN)4]
B.
0.1M K3[Co(CN)6]
C.
0.1M Na3[CoBr6]
D.
0.1 M Na4[CoF6]
E.
0.1 M [Ni(NH3)4]Cl2
----------------------------------------------------------------------------------------------------------------21. Place the following compounds (N2, NO, N2H4, N2O4, NO3–, NH4+) in order from
highest oxidation state of nitrogen to lowest oxidation state of nitrogen.
A.
N2 > NO > NO3– > N2O4 > N2H4 > NH4+
B.
NO3– > NO > N2O4 > N2H4 > N2 > NH4+
C.
N2O4 > N2 > NO > N2H4 > NH4+ > NO3–
D.
NO3– > N2O4 > NO > N2 > N2H4 > NH4+
E.
N2O4 > NO3– > N2H4 > NH4+ > NO > N2
----------------------------------------------------------------------------------------------------------------22. Which of the following represent n-type semiconductors?
I.
II.
III.
IV.
A.
I only
B.
II only
C.
III only
D.
IV only
E.
III and IV
Si
As-doped Si
Zn-doped Si
AlP
---------------------------------------------------------------------------------------------------------------------
Go on to the next page
--------------------------------------------------------------------------------------------------------------------23. Calculate the activation energy of a reaction that has a rate constant of
4.41  103s1 at 183 K and rate constant of 9.79  102s1 at 315 K.
A.
2.67 kJ/mol
B.
2.90 kJ/mol
C.
0.0589 kJ/mol
D.
11.3 kJ/mol
E.
16.4 kJ/mol
--------------------------------------------------------------------------------------------------------------------24. What is the value of the equilibrium constant for the following reaction:
2NO(g) +O2(g) ⇆ 2NO2(g)
Given:
A.
8.5  102
B.
4.5  105
C.
2.3  10−6
D.
7.0  10−4
E.
1.6
Kc = ???
2NO(g) ⇆ N2(g) + O2(g)
Kc = 1.9  10−3
2NO2(g) ⇆ N2(g) + 2 O2(g)
Kc = 1.2  10−3
--------------------------------------------------------------------------------------------------------------------25. The half-life of 239Pu is 24,000 years. What fraction of the 239Pu present in nuclear
wastes generated in 2000 will be present in the year 3000?
A.
0.95
B.
0.92
C.
1.03
D.
0.97
E.
0.90
---------------------------------------------------------------------------------------------------------------------
Go on to the next page
--------------------------------------------------------------------------------------------------------------------26. Pick the strongest base from the following list.
A.
PO43− (H3PO4: Ka1 = 7.5  10−3; Ka2 = 6.2  10−8; Ka3 = 4.2  10−13)
B.
NH3 (Kb = 1.8  10−5)
C.
N3− (Ka for HN3 = 1.9  10−5)
D.
NO3−
E.
F− (Ka for HF = 6.8  10−4)
--------------------------------------------------------------------------------------------------------------------27. Calculate the pH of a solution prepared by dissolving 0.37 moles of formic acid
(HCOOH) and 0.23 moles of sodium formate (NaCOOH) in 1.00 L of solution.
(Ka = 1.8  10−4.)
A.
2.09
B.
10.46
C.
3.54
D.
2.30
E.
4.25
--------------------------------------------------------------------------------------------------------------------28. Given that Ka for HNO2 is 5.0  10−4, calculate the equilibrium constant for the
following reaction
NO2−(aq) + H2O ()  HNO2 (aq) + OH−(aq)
A.
5  10−4
B.
5  1010
C.
2  10−4
D.
5  1018
E.
2  10−11
---------------------------------------------------------------------------------------------------------------------
Go on to the next page
--------------------------------------------------------------------------------------------------------------------29. What is the Keq value for the following reaction at 25C?
2NO2 (g) ⇆ N2O4 (g)
Gf NO2 (g) = 51.30 kJ/mol
Gf N2O4 (g) = 97.82 kJ/mol
A.
1.9
B.
6.9
C.
1.4  108
D.
1.4  10−8
E.
1.9  103
--------------------------------------------------------------------------------------------------------------------30. A 0.10 M aqueous solution of which of the following salts will have the lowest pH?
A.
KNO3
B.
Ca(NO3)2
C.
Fe(NO3)3
D.
KCl
E.
BaBr2
---------------------------------------------------------------------------------------------------------------------
Go on to the next page
--------------------------------------------------------------------------------------------------------------------Use this energy level diagram to answer the next question.
31. Which of the following has one unpaired electron?
A.
O2
B.
O22–
C.
NO
D.
CN–
E.
CO
--------------------------------------------------------------------------------------------------------------------32. [CoCl6]3− is orange while [Co(NH3)6]3+ is yellow. Which of the following statements
is correct?
A.
[CoCl6]3− absorbs orange light.
B.
The crystal field splitting parameter  is larger for [CoCl6]3− than for
[Co(NH3)6]3+.
C.
The spectrochemical series ordering is Cl− > NH3.
D.
The two sets of d orbitals are split further apart in [Co(NH3)6]3+ than they
are in [CoCl6]3−.
E.
The different colors are due to the different charges on the complexes.
------------------------------------------------------------------------------------------------------------------
Go on to the next page
-----------------------------------------------------------------------------------------------------------------33. Which of these orbitals are bonding orbitals (i.e., a molecular orbital that is the
result of CONSTRUCTIVE interference)?
i
ii
iii
iv
v.
A.
v only
B.
i and ii
C.
ii and iv
D.
i, iii, and v
E.
iii and iv
--------------------------------------------------------------------------------------------------------------------34. The most probable mode of decay of 40Cl is
A.
 emission
B.
 emission
C.
positron emission
D.
neutron emission
E.
electron capture
---------------------------------------------------------------------------------------------------------------------
Go on to the next page
----------------------------------------------------------------------------------------------------------------35. Consider the complex ions of Cr3+ and their color shown below. Which one of the
following ligands will result in the smallest value of ?
[Cr(CN)6]3−
YELLOW
[Cr(NH3)6]3+ YELLOW
[CrF6]3−
GREEN
[Cr(H2O)6]3+
VIOLET
A.
F−
B.
NH3
C.
H2O
D.
CN−
E.
NH3 and CN−
--------------------------------------------------------------------------------------------------------------------36. What is the binding energy per nucleon of 35Cl, given that the 35Cl nuclear mass
is 34.9502 amu?
A.
1.41  10−12 J
B.
4.93  10−11 J
C.
1.56  10−12 J
D.
1.56  10−11 J
E.
1.56  10−10 J
--------------------------------------------------------------------------------------------------------------------37.
A 40.0 mL sample of 0.100 M NH3 is titrated with 0.100 M HCl. What is the pH
after the addition of 40 mL of HCl? Kb for NH3 is 1.8  10−5.
A.
11.6
B.
10.5
C.
8.17
D.
5.28
E.
3.61
---------------------------------------------------------------------------------------------------------------------
Go on to the next page
--------------------------------------------------------------------------------------------------------------------38.
An electrochemical cell is made with one Zn electrode and one Cu electrode, in
2.0 M Zn(NO3)2 and 0.1 M Cu(NO3) 2 solutions, respectively. The two solutions
are connected by a salt bridge.
The standard half-cell reduction potentials for Cu2+(aq) + 2e−  Cu(s) and
Zn2+(aq) + 2e−  Zn(s) are +0.34 and 0.76 V, respectively. Which one of the
following statements is false?
A.
The overall cell potential is 1.10 V.
B.
The Cu electrode is the cathode.
C.
Electrons flow in the external circuit from Cu to Zn.
D.
After current flows for a long time, the cell voltage approaches zero.
E.
The standard free energy change for the reaction Cu2+(aq) + Zn(s) = Cu(s)
+ Zn2+(aq) is negative.
-----------------------------------------------------------------------------------------------------------39. Kp for the reaction is 3.89  10–34 at 298.15 K.
2HCl(g) ⇆ H2(g) + Cl2(g)
Which of the following is true?
A.
This reaction is exothermic.
B.
Gf for HCl(g) is –95.3 kJ mol–1.
C.
This reaction is spontaneous.
D.
S = 0 J mol–1 K–1.
E.
G for the reaction is +76.9 kJ mol–1.
---------------------------------------------------------------------------------------------------------------------
Go on to the last page
--------------------------------------------------------------------------------------------------------------------40. The results of several experiments for the same reaction are plotted in the figure
below. Which statements about these data are correct?
i. The experiments were all done at the same temperature.
ii. Lines1 and 2 represent experiments done with the same
starting concentration.
iii. Line 3 represents the experiment that was done at the
lowest temperature.
A.
i only
B.
ii only
C.
iii only
D.
i and ii
E.
all three are true
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
END OF EXAM
Data Sheet
3. Equations
Half-reaction
F2(g) + 2e– → 2F–(aq)
H2O2(aq) + 2H+(aq) + 2e− →2H2O(l)
Cl2(g) + 2e– → 2Cl–(aq)
O2(g) + 4H+(aq) + 4e– → 2H2O(l)
Br2(l) + 2e– → 2Br–(aq)
Ag+(aq) + e– → Ag(s)
Fe3+(aq) + e– → Fe2+(aq)
O2(g) + 2H+(aq) + 2e– → H2O2(aq)
I2(s) + 2e– → 2I–(aq)
Cu2+(aq) + 2e– → Cu(s)
Sn4+(aq) + 2e−→ Sn2+(aq)
Cu2+(aq) + e– → Cu+(aq)
2H+(aq) + 2e− → H2(g)
Pb2+(aq) + 2e− → Pb(s)
Sn2+(aq) + 2e− → Sn(s)
Co+2(aq) + 2e−→ Co(s)
Ni2+(aq) + 2e– → Ni(s)
Cd2+(aq) + 2e– → Cd(s)
Fe2+(aq) + 2e– → Fe(s)
Cr3+(aq) + 3e– → Cr(s)
Zn2+(aq) + 2e– → Zn(s)
2H2O(l) + 2e− → H2(g) + 2OH−(aq)
SO42−(aq) + H2O(l) + 2e− → SO32−(aq) + 2OH−(aq)
Mn2+(aq) + 2e– → Mn(s)
Al3+(aq) + 3e– → Al(s)
Mg2+(aq) + 2e– → Mg(s)
Ca2+(aq) + 2e– → Ca(s)
Li+(aq) + e– → Li(s)
2. Constants
R = 8.314 J mol–1K–1
R = 0.0821 L-atm mol–1K–1
F = 96,500 coulombs mol–1
h = 6.62606876 x 10–34 J-s
1
mass 0 n = 1.0086649 amu
mass
1
1p
= 1.0072765 amu
1 g = 6.02 x 1023 amu
Eo1/2(V)
+2.87
+1.78
+1.36
+1.23
+1.07
+0.80
+0.77
+0.68
+0.54
+0.34
+0.154
+0.153
–0.00
–0.126
–0.136
−0.277
–0.28
–0.40
–0.44
–0.74
–0.763
−0.83
−0.93
–1.18
–1.66
–2.37
–2.76
–3.05
log
∆G = ∆H – T∆S = –nFE
∆Go = –2.303 RT log K = –RT ln K
∆G = ∆Go + RT ln Q
Nt
− kt
− 0.301t
=
=
t1
No
2.303
c = 2.99792458 x 108m sec–1
kg m 2
1J=
= C-V
sec 2
E = mc2
2
N
− 0.693t
ln t =
= –kt
No
t1
k=
0.693
t1
2
2
∆G = ∆Go + 2.303 RT log Q
0.059
log K
E =
n
o
4. Diagram of d-orbitals for octahedral complexes
o
(at 25 C)
0.059
log Q (at 25oC)
n
[X − ]
pH = pKa + log
[ HX ]
E = Eo –
dx² – dy², dz²
Ka x Kb = Kw = [H+] [OH–]
dxy, dyz, dxz
pKw = pH + pOH = pKa + pKb
Kp = Kc (RT)Δn
Kw = 1 x 10–14 at 25°C
− Ea
ln k =
RT
E
k
ln 1 = a
k2
R
k = Ae(–
5. Color Wheel, with Wavelength Range
680 nm
+ ln A
⎛ 1 1 ⎞
⎜ − ⎟
⎝T 2 T1 ⎠
400 nm
620 nm
Violet
Red
Εa
RT )
Blue
1 amp = 1 coul sec–1
Avogadro’s no. = 6.02214 x 1023 mol–1
Rate = kN
Energy
1. Standard Electrode Potentials
Orange
ln[A] = ln[A]o –kt
1
1
=
+ kt
[A] [A]o
Green
Yellow
480 nm
590 nm
550 nm
∆
PERIODIC TABLE of the ELEMENTS
MAIN GROUPS
1A
1
1
H
1.008
MAIN GROUPS
2A
2
3
Li
4
Be
6.941
9.012
11
Na
12
Mg
22.990
24.305
19
K
TRANSITION METALS
8A
18
2
He
3A
13
4A
14
5A
15
6A
16
7A
17
5
B
6
C
7
N
8
O
9
F
10
Ne
10.811
12.011
14.007
15.999
18.998
20.180
13
Al
14
Si
15
P
16
S
17
Cl
18
Ar
26.982
28.086
30.974
32.066
35.453
39.948
4.003
3B
3
4B
4
5B
5
6B
6
7B
7
8B
8
8B
9
8B
10
1B
11
2B
12
20
Ca
21
Sc
22
Ti
23
V
24
Cr
25
Mn
26
Fe
27
Co
28
Ni
29
Cu
30
Zn
31
Ga
32
Ge
33
As
34
Se
35
Br
36
Kr
39.098
40.078
44.956
47.867
50.942
51.996
54.938
55.845
58.933
58.693
63.546
65.39
69.723
72.61
74.992
78.96
79.904
83.80
37
Rb
38
Sr
39
Y
40
Zr
41
Nb
42
Mo
43
Tc
44
Ru
45
Rh
46
Pd
47
Ag
48
Cd
49
In
50
Sn
51
Sb
52
Te
53
I
54
Xe
85.468
87.62
88.906
91.224
92.906
95.94
[98]
101.07
102.90
106.42
107.87
112.41
114.82
118.71
121.76
127.60
126.90
131.29
55
Cs
56
Ba
57
La*
72
Hf
73
Ta
74
W
75
Re
76
Os
77
Ir
78
Pt
79
Au
80
Hg
81
Tl
82
Pb
83
Bi
84
Po
85
At
86
Rn
132.91
137.33
138.91
178.49
180.95
183.84
186.21
190.23
192.22
195.08
196.97
200.59
204.38
207.2
208.98
[209]
[210]
[222]
87
Fr
88
Ra
89
Ac**
104
Rf
105
Db
106
Sg
107
Bh
108
Hs
109
Mt
110
111
112
114
116
118
[223]
[226]
[227]
[261]
[262]
[266]
[264]
[265]
[268]
[269]
[272]
[277]
[285]
[289]
[293]
58
Ce
59
Pr
60
Nd
61
Pm
62
Sm
63
Eu
64
Gd
65
Tb
66
Dy
67
Ho
68
Er
69
Tm
70
Yb
71
Lu
140.12
140.91
144.24
[145]
150.36
151.96
157.25
158.92
162.50
164.93
167.26
168.93
173.04
174.97
90
Th
91
Pa
92
U
93
Np
94
Pu
95
Am
96
Cm
97
Bk
98
Cf
99
Es
100
Fm
101
Md
102
No
103
Lr
232.04
231.04
238.03
[237]
[244]
[243]
[247]
[247]
[251]
[252]
[257]
[258]
[259]
[262]
* LANTHANOIDS
** ACTINOIDS