Download Final Exam - W09

Last Name: _____________________________ First Name: _______________
Lab Sec. # ____
TA: ____________________ Lab day/time: _____________
Dr. Enderle
CHEMISTRY 2A (D)
Final Exam – Winter 2009
Multiple Choice
Circle one
Instructions:
CLOSED BOOK EXAM! DO NOT OPEN the exam until instructed to do so.
No books, notes, or additional scrap paper are permitted. All information
required is contained on the exam. Place all work in the space provided. If you
require additional space, use the back of the exam. A scientific calculator may
be used (if it is a programmable calculator, its memory must be cleared before
the exam). Sharing of calculators is not allowed.
(1)
(2)
(3)
(4)
(5)
Read each question carefully (27 problems, 15 pages).
ANSWER ALL THE QUESTIONS YOU ARE SURE OF FIRST, AND
THEN USE THE REMAINING TIME FOR THE REST.
Please show all relevant work where it is indicated for full credit.
The last 2 pages contain a periodic table and some useful information.
You may remove them for easy access and for scratch.
If you finish early, RECHECK YOUR ANSWERS!
UC Davis is an Honor Institution
Possible Points
Points
1.
a
b
c
d
e
2.
a
b
c
d
e
3.
a
b
c
d
e
4.
a
b
c
d
e
5.
a
b
c
d
e
6.
a
b
c
d
e
7.
a
b
c
d
e
8.
a
b
c
d
e
9.
a
b
c
d
e
10.
a
b
c
d
e
11.
a
b
c
d
e
# 1-13
(3 points each)
/ 39
12.
a
b
c
d
e
# 14-19
(5 points each)
/ 30
13.
a
b
c
d
e
# 20
(6 points)
/ 06
1 - 1 3 total points:
# 21
(42 points)
/ 42
14.
a
b
c
d
e
# 22
(10 points)
/ 10
15.
a
b
c
d
e
# 23
(10 points)
/ 10
16.
a
b
c
d
e
# 24
(06 points)
/ 06
17.
a
b
c
d
e
# 25
(30 points)
/ 30
18.
a
b
c
d
e
# 26
(06 points)
/ 06
19.
a
b
c
d
e
# 27
(16 points)
/ 16
1 4- 1 9 total points:
Total Score (195)
/ 195
WINTER 2009
FINAL CHEM 2A
(Page 2 of 15)
Concepts: Multiple Choice
Questions 1-13: 3 points each (no partial credit)
1.
Write the symbol of the species that has 28 protons, 26 electrons, and 32
neutrons.
58
Fe2+
60
Ni260
Ni2+
60
Fe2+
60
Ni3+
a)
b)
c)
d)
e)
2.
In the reaction, H2O2  H2O + 1/2O2 oxygen is:
a. Reduced
b. Oxidized
c. Both a. and b.
d. Neither a. nor b.
e. Annihilated
3.
How many σ bonds does the molecule of guanine have?
a)
b)
c)
d)
e)
4.
17
2
3
4
0
N
C
C
NH
HC
C
N
H
C
N
NH2
Choose the INCORRECT formula-name combination.
a.
b.
c.
d.
Na2CO3
P2O5
FeBr2
N2O3
e. K3N
5.
O
sodium carbonate
diphosphorus pentoxide
iron dibromide
dinitrogen trioxide
potassium nitride
In which of the following compounds does chlorine have the highest oxidation
number?
(a) ClO2
(b) Cl2
(c) FeCl3
(d) KClO3
(e) Mg(ClO)2
WINTER 2009
6.
7.
FINAL CHEM 2A
(Page 3 of 15)
Which of the following reactions is NOT a redox reaction?
(a)
5 I– (aq) + IO3– (aq) + 6 H+ (aq)  3 I2 (s) + 3 H2O (l)
(b)
Zn (s) + Cu2+ (aq)  Zn2+ (aq) + Cu (s)
(c)
2 H2O2 (aq)  2 H2O (l) + O2 (g)
(d)
BaCl2 (aq) + Na2SO4 (aq)  BaSO4 (s) + 2NaCl (aq)
(e)
CH3COOH (aq) + 2 O2 (g)  2 CO2 (g) + 2 H2O (l)
Which statement is FALSE about the 5dxy orbital?
(a) It has a nodal plane in the xz plane.
(b) It has a nodal plane in the yz plane.
(c) For an electron in the 5dxy orbital there is a higher probability of finding the
electron farther from the nucleus than if it is in the 5s orbital.
(d) It can hold a total of 10 electrons.
(e) None of the above.
8.
Choose the species from which one electron could most easily be removed.
(a) Cl
(b) Na+
(c) Na
(d) K
(e) Ar
9.
Which of the following has the largest radius?
(a) As3–
(b) Br–
(c) Sr2+
(d) Cl
(e) They all have approximately the same size
10.
Using the VSEPR theory, which one of the following chemical species would you
expect to have a dipole moment (polar)?
a.
I3–
b.
O3
c.
CO2
d.
CH4
e.
None of the above
WINTER 2009
11.
FINAL CHEM 2A
(Page 4 of 15)
What is the bond order of the nitrogen-oxygen bonds in the nitrate ion?
(a) 2, 1, and 1
(b) 1, 2, and 2
(c) 1.33
(d) 1
(e) 2
12.
13.
Choose the INCORRECT statement about the molecule of HCN.
a.
There are a total of two σ bonds in the molecule.
b.
There are a total of two π bonds in the molecule.
c.
There is a lone pair on nitrogen.
d.
The molecule is bent.
e.
The carbon atom has sp hybridization.
Which of the following is NOT TRUE about a mixture of gases?
a. The sum of the partial pressures of each gas is equal to the total pressure.
b. The sum of the moles of each gas is equal to the total number of moles.
c. The sum of the temperature of each gas is equal to the total temperature.
d. The sum of the partial volumes of each gas is equal to the total volume.
e. All of the above statements are true.
WINTER 2009
FINAL CHEM 2A
(Page 5 of 15)
Calculations: Multiple Choice
Questions 14-19: 5 points each (no partial credit)
14.
A hypothetical element, E, has two stable isotopes:
E-38 = 38.012 u
75.68%
E-46 = 45.981 u
24.32%
The element’s atomic mass would be closest to which element?
(a)
K
(b) Ar
(c)
Ca
(d) Sc
(e) Sr
15.
Find the empirical formula for a compound with the following mass composition:
K 42.4%, Fe 15.2%, C 19.5% and N 22.8%.
a.
KFeCN
b.
K4FeC6N6
c.
KFeC6N6
d.
K4FeCN6
e.
K4FeC6N
WINTER 2009
16.
FINAL CHEM 2A
(Page 6 of 15)
You have a 1.212 M stock aqueous solution of Sr(OH)2. What volume of the
stock solution (in mL) must be diluted with water to prepare 50.00 mL of a solution
that has a hydroxide concentration [OH–] = 0.2000 M?
17.
a.
6.455 mL
b.
1.294 mL
c.
2.528 mL
d.
4.125 mL
e.
8.173 mL
When chlorine is added to acetylene, 1,1,2,2-tetrachloroethane is formed:
2 Cl2(g) + C2H2(g)  C2H2Cl4(l)
How many liters of chlorine gas at STP will be needed to make 75.0 grams of
C2H2Cl4?
a.
10.0 L
b.
20.0 L
c.
30.0 L
d.
40.0 L
e.
50.0 L
WINTER 2009
18.
19.
FINAL CHEM 2A
(Page 7 of 15)
Consider an electron moving at 1 x 106 m/s. Find its wavelength in angstroms.
a.
1Å
b.
3Å
c.
5Å
d.
7Å
e.
9Å
The energy of a photon is used to completely remove the electron of a hydrogen
atom. What is the wavelength of the photon in nanometers if the electron is
removed from its second orbit?
a)
b)
c)
d)
e)
365 nm
410 nm
434 nm
486 nm
656 nm
WINTER 2009
FINAL CHEM 2A
(Page 8 of 15)
20. (6 points) Fill in the blanks with the correct ground state electron configuration (noble
gas configuration) for the given atom or the atom for the given ground state electron
configuration of the neutral atom.
Atom
Electron Configuration
Sn
[Ar] 3d10 4s1
21. (42 points) Fill in the following table (see the ClF3 example).
For the determination of formal charge(s) consider the Lewis formula with the
smallest formal charges (lowest energy).
Molecule
Electron-Group
Geometry
(central atom)
Molecular Geometry
Ideal
Bond
Angles
ClF3
TrigonalBipyramidal
T- shape
90º , 1 80º
CCl2Br2
PCl3
CO2
H 2O
XeF4
SF4
Formal Oxidation
HybridPolar or
Charge(s) Number
ization
Nonpolar
of the
of the
(central
Molecule
underlined underlined
atom)
element element
polar
sp3d
0
-1
WINTER 2009
FINAL CHEM 2A
(Page 9 of 15)
Partial Credit. Show ALL Your Work. Explain.
22. (10 points)
If 10.0 g of sodium hydrogen carbonate is added to 450 mL of a 0.155 M aqueous
solution of copper(II) nitrate and left to react according to the reaction:
2NaHCO3(aq) + Cu(NO3)2(aq)  CuCO3(s) + 2NaNO3(aq) + H2O(l) + CO2(g)
How many liters of carbon dioxide are produced at STP?
V=
WINTER 2009
FINAL CHEM 2A
(Page 10 of 15)
23. (10 points)
A civil engineer wants to reduce odors at a wastewater treatment plant by
adding hydrogen peroxide to the sewage. The hydrogen peroxide is delivered as
50% by mass solution, but for maintenance and safety issues, the H2O2 is diluted to
a 3% by mass solution. If the engineer needs 20.0 gallons of the 3% by mass
aqueous solution of H2O2, how many gallons of water does the engineer need to add
to the 50% solution?
(Density of 50% solution = 1.197 g/mL; density of 3% solution = 1.015 g/mL)
Volume of water =
24.
(6 points) Consider the molecule of ozone, O3.
A)
Draw its two resonance Lewis electron dot diagrams.
B)
What is the electron group geometry of its central atom?
C)
What is its molecular geometry?
D)
What is the hybridization of its central atom?
E)
What is the ideal bond angle?
F)
Is it polar or nonpolar molecule?
A)
B)
C)
D)
E)
F)
WINTER 2009
25.
FINAL CHEM 2A
(Page 11 of 15)
(30 points) Complete the MO energy level diagram for the cation B2+.
a.
Fill in the electrons using arrows (↑ and/or ↓) for the atomic and molecular
orbitals.
b.
Designate all the energy levels (i.e., σ2s*, π2p, σ2s, etc.)
c.
Calculate the bond order for B2+.
d.
Is B2+ a paramagnetic or diamagnetic chemical species?
a. and b.
2p
2p
E
2s
B
c.
d.
Bond order for B2+ =
Paramagnetic or Diamagnetic?
Answer:
2s
B2
+
B+
WINTER 2009
FINAL CHEM 2A
(Page 12 of 15)
26. (6 points)
Write the possible four quantum numbers n, l, ml, and ms for each of the following
electrons.
2s
4d
5f
WINTER 2009
27.
FINAL CHEM 2A
(Page 13 of 15)
(16 points)
Balance the following chemical equation by the half-reaction method
and show your work. Next, answer the following questions.
CH4O + O2
CO2 + H2O
Note! The above chemical equation is very easy to balance just by inspection. You
are NOT asked to balance it by the inspection method. Balancing it by the
inspection method will result in zero points for credit.
a. The oxidizing chemical species is:
b. The reducing chemical species is:
c. The name of the oxidized element is:
d. The name of the reduced element is:
e. The oxidant’s molecular formula is:
f. The reductant’s molecular formula is:
g. The name of the element that gains electrons is:
h. The name of the element that loses electrons is:
i.
The chemical species that causes oxidation is:
j.
The chemical species that causes reduction is:
k. The oxidation number of ____ (give the chemical symbol of the element)
increases from ____ to ____
l.
The oxidation number of ____ (give the chemical symbol of the element)
decreases from ____ to ____
WINTER 2009
FINAL CHEM 2A
(Page 14 of 15)
Solubility rules:
Compounds which are soluble or mostly soluble:
•
Group 1, NH4+, chlorates, acetates, nitrates
•
Halides (except Pb2+, Ag+, and Hg22+)
•
Sulfates (except Sr2+, Ba2+, Pb2+, and Hg22+)
Compounds which are insoluble:
•
•
Hydroxides, sulfides (except above rule, and sulfides of group 2)
Carbonates, phosphates, chromates (except above rules)
Some useful equations and data:
PLEASE NOTE: Important values and equations required for calculations are given
with the respective problem. The following may or may not be of any use.
λ=
h
mυ
d=
PM
RT
Molarity =
Moles
Liter
n (moles) =
mass (g)
molar mass (g/mol)
PV = nRT
NA = 6.022 x 1023
h = 6.626x10-34 Js
1 J = 1 kg m2 s-2 = 1 N m
mL∙M = mmol
Ptotal = P1 + P2 + …
TK = ToC + 273
R = 0.0821 L atm mol-1 K-1
1 nm = 10-9 m
c = 3.00 x 108 m s-1
c = νλ
xA = nA / ntot = PA / Ptot
Ephoton = hν
Rate2/Rate1=(M1/M2)1/2
Z2
En = − RH 2
n
d=
m
V
∆x ⋅ ∆p =
RH = 2.179 x 10
-18
J
me = 9.109387x10-28 g
h
4π
1 atm = 760 mmHg
1 g = 6.022x1023 amu
∆ p = m ∆υ
∆E = RH(1/ni2 – 1/nf2)
1 Å = 10-10 m
% Yield =
Actual Yield
Theoretical Yield
x100
WINTER 2009
FINAL CHEM 2A
(Page 15 of 15)
Potentially Useful Information
(You may remove this page for ease of access)
Key
1
Atomic Number
Symbol
Atomic Mass
Electronegativity
H
1.008
2.20
3
2
He
4.003
-
4
5
6
7
8
9
10
Li
Be
B
C
N
O
F
Ne
6.941
0.98
9.012
1.57
10.81
2.04
12.01
2.55
14.01
3.04
16.00
3.44
19.00
3.98
20.18
-
11
Na
Mg
Al
Si
14
15
16
S
Cl
Ar
22.99
0.93
24.31
1.31
26.98
1.61
28.09
1.90
30.97
2.19
32.06
2.58
35.45
3.16
39.95
-
19
12
Ti
22
23
V
Cr
Mn
Fe
Co
Ni
Cu
Zn
Ga
Ge
As
Se
Br
Kr
39.10
0.82
40.08
1.00
44.96
1.36
47.90
1.54
50.94
1.63
52.00
1.66
54.94
1.55
55.85
1.83
58.93
1.88
58.70
1.91
63.55
1.90
65.38
1.65
69.72
1.81
72.59
2.01
74.92
2.18
78.96
2.55
79.90
2.96
83.80
-
38
39
52
53
87.62
0.95
88.91
1.22
127.6
2.1
126.9
2.66
85.47
0.82
55
Cs
56
Ba
Y
71
Lu
132.9
0.79
87
137.3
0.89
175.0
1.27
88
103
(223)
0.7
(226)
0.9
(260)
-
Fr
Ra
Lr
40
Zr
91.22
1.33
72
Hf
178.5
1.3
41
Nb
92.91
1.6
73
Ta
42
Mo
95.94
2.16
74
W
25
43
Tc
(98)
1.9
75
Re
104
180.9
1.5
105
183.9
2.36
106
186.2
1.9
107
-
-
-
-
Unq
57
Unp
58
Unh
59
Uns
60
26
44
Ru
101.1
2.2
76
Os
190.2
2.2
-
61
27
45
Rh
102.9
2.28
77
Ir
192.2
2.20
28
46
Pd
106.4
2.20
78
Pt
195.1
2.28
29
47
Ag
107.9
1.93
79
Au
197.0
2.54
30
48
Cd
112.4
1.69
80
Hg
200.6
2.00
31
49
In
114.8
1.78
81
Tl
204.4
2.04
32
50
Sn
33
51
Sb
118.7
1.96
121.8
2.05
82
83
207.2
2.33
209.0
2.02
Pb
Bi
34
Te
84
Po
(209)
2.0
35
18
Sc
Sr
24
17
Ca
37
21
P
K
Rb
20
13
I
85
At
(210)
2.2
109
Une
-
62
63
64
65
66
67
68
69
70
La
Ce
Pr
Nd
Pm
Sm
Eu
Gd
Tb
Dy
Ho
Er
Tm
Yb
138.9
1.10
140.1
1.12
140.9
1.13
144.2
1.14
(145)
1.13
150.4
1.17
152.0
1.2
157.3
1.20
158.9
1.2
162.5
1.22
164.9
1.23
167.3
1.24
168.9
1.25
173.0
1.1
89
Ac
Th
90
Pa
91
92
U
Np
93
Pu
94
Am
95
Cm
96
Bk
97
Cf
98
Es
99
Fm
100
Md
101
No
102
(227)
1.1
232.0
1.3
(231)
1.5
238.0
1.38
(237)
1.36
(244)
1.28
(243)
1.3
(247)
1.3
(247)
1.3
(251)
1.3
(252)
1.3
(257)
1.3
(258)
1.3
(259)
1.3
36
54
Xe
131.3
86
Rn
(222)
-