Exam #3 - A
Chemistry 130
Name:
December 6, 2010
Lab Day and Time:
Instructions
1. Do not open the exam until you are told to start.
2. This exam is closed note and closed book. You re not allowed to use any outside material
while taking this exam.
3. Use the spaces provided to write down your answers. To receive full credit, you must
show all work. Do not write answers on any other pieces of paper. If you need more room,
write on the back of the exam and be sure to include a note describing where the work is
located.
4. When solving numerical problems, make sure you include the proper units in your final
answer.
5. If a question asks for a response in sentence or paragraph form, make sure you respond in
that format.
6. Useful data for the exam and a periodic table are provided on the last page of the exam.
Carefully tear out these sheets if you wish.
Page #
Points possible
2-5 (MC)
45
5
11
6
26
7
15
In-Class EC
3
Attendance
3
Total
100
1
Points awarded
Exam #3 - A
Chemistry 130
December 6, 2010
Multiple Choice
Unless otherwise directed, choose the single best answer for each question. Some of the
chemical equations will be balanced and some will not. Make sure you balance all of the
equations before doing calculations. Each question is worth three points.
1. Use the chemical equation below to calculate the moles of AlBr3 that will be formed when
6.0 mole of Br2 is reacted with an excess of Al.
Al(s) + Br2(g)
a.)
b.)
c.)
d.)
e.)
Æ AlBr3(s)
2.0 mol
3.0 mol
4.0 mol
6.0 mol
8.0 mol
When methane is combusted, it reacts with O2 and produces CO2 and H2O. The balanced chemical
equation for this reaction is shown below. Use this equation and the diagrams below to answer
the following question.
CH4(g) + 2O2(g) Æ CO2(g) + 2H2O(g)
hydrogen
oxygen
carbon
Before Reaction
After Reaction
2. Which compound is the limiting reagent?
a.)
b.)
c.)
d.)
e.)
CH4
O2
CO2
H2O
None of the above.
3. The number of unpaired electrons in a Co atom is _______.
a.)
b.)
c.)
d.)
e.)
2
3
5
7
None of the above.
4. Which of the following elements is the largest?
a.)
b.)
c.)
d.)
e.)
Na
Mg
P
N
O
2
Exam #3 - A
Chemistry 130
December 6, 2010
5. According to the chemical equation shown below, what mass of carbon dioxide would be
produced when 10.0 g of C4H10 reacts with an excess of oxygen?
Molar Mass (g/mole)
a.)
b.)
c.)
d.)
e.)
2C4H10(g) + 13O2(g) Æ 8CO2(g) + 10H2O(g)
58.123
31.9988
44.010
18.0153
7.57 g CO2
30.3 g CO2
40.0 g CO2
352 g CO2
None of the above.
6. An acidic solution is made by dissolving 14.7 g of H2SO4 in enough water to make
2.00x102 mL of solution. What is the molarity of this H2SO4 solution?
a.)
b.)
c.)
d.)
e.)
1.33 M
0.749 M
0.770 M
0.0735 M
None of the above.
7. Which one of the following elements has the largest ionization energy?
a.)
b.)
c.)
d.)
e.)
K
Ca
N
C
O
8. The point in a titration at which the indicator changes color is called the __________.
a.)
b.)
c.)
d.)
e.)
equivalence point
indicator point
end point
standard point
None of the above.
9. A chemist adds 25.00 mL of deionized water to a beaker that contains 100.0 mL of a 2.50 M
K2C2O4 solution. How many moles of K2C2O4 are in the beaker?
a.)
b.)
c.)
d.)
e.)
0.0625 moles of K2C2O4
0.313 moles of K2C2O4
2.50 moles of K2C2O4
0.250 moles of K2C2O4
None of the above
3
Exam #3 - A
Chemistry 130
December 6, 2010
10. How many valence electrons does Ag contain?
a.) 1
b.) 2
c.) 10
d.) 11
e.) None of the above.
11. A 13.8 mL sample of 0.176 M H3PO4(aq) is titrated with a 0.110 M NaOH solution. What
volume (mL) of the NaOH solution will it take to reach the equivalence point of the titration?
a.)
b.)
c.)
d.)
e.)
7.29 mL
22.1 mL
199 mL
66.2 mL
None of the above.
12. What is the concentration of HBr in a solution made by adding 150.0 mL of water to 125.0 mL
of 0.200 M HBr?
a.)
b.)
c.)
d.)
e.)
0.167 M HBr
0.240 M HBr
0.0909 M HBr
0.0750 M HBr
None of the above.
13. When a 1.25 L solution of 0.250 M MgCl2 is mixed with 1.30 L of 0.250 M AgNO3, what is
the mass of AgCl that is produced?
Molar Mass (g/mole)
a.)
b.)
c.)
d.)
e.)
MgCl2(aq) + 2AgNO3 Æ 2AgCl(s) + Mg(NO3)2(aq)
95.2104
169.8731 143.3209 148.3149
89.6 g
43.0 g
133 g
46.6 g
None of the above.
4
Exam #3 - A
Chemistry 130
December 6, 2010
14. When NH3 is prepared from the reaction of 2.237 g of H2 with excess N2, the actual yield of
NH3 is 11.10 g. Calculate the percent yield.
Molar Mass (g/mole)
a.)
b.)
c.)
d.)
e.)
N2(g) + 3H2(g) Æ 2NH3(g)
28.01348 2.01588 17.03056
6.667%
88.10%
20.15%
82.00%
None of the above.
15. Chromium(V) nitrate is soluble in water. What is the concentration of NO3- in a
0.250 M Cr(NO3)5 solution?
a.)
b.)
c.)
d.)
e.)
a.)
1.25 M NO30.0500 M NO30.250 M NO31.00 M NO3None of the above.
16. In the space provided below give a.) the full electron configuration of the element that is
underlined, b.) draw the Bohr representation of each element, and c.) calculate the effective
nuclear charge (Zeff) felt by the valence electrons in each of the atoms. (8 points)
Mg
Al
a.)
b.)
b.)
c.)
c.)
17. Suppose both of the elements above absorbed a photon of 400 nm light and had an electron
promoted to an excited state.
a.) What color of light was absorbed? (1 point)
b.) In which atom did the electron travel the longest distance? (2 points)
5
Exam #3 - A
Chemistry 130
December 6, 2010
18. When atoms react, they do so by gaining electrons, losing electrons, or sharing electrons. The
ease with which they can do these things affects their reactivity. Based on your knowledge of
effective nuclear charge, the trends in first ionization energy, the trends in atomic size, and the
ways in which metals and non-metals react, pick the atom in each set that you predict to be
the most reactive. (4 points)
i.) F, Cl, Br
ii.) Au, Ba, Cs
19. In the table below, the name or formula for a chemical compound is given. Fill in the table
with the corresponding name or formula of the chemical compound. (6 points)
NAME
FORMULA
HBrO
calcium acetate
Zn3(PO3)2
20. Tetraphosphorus trisulfide, P4S3, is used in the heads of wooden matches. This material can be
manufactured by heating a mixture of red phosphorus and sulfur. The balanced chemical
equation for this process is shown below.
8P4(s) + 3S8(s) Æ 8P4S3(s)
Molar Mass (g/mole)
123.8950 256.528
220.093
a.) If you start with 24.8 g of P4 and 25.7 g of S8, what mass of P4S3 will you produce?
(12 points)
b.) How much of each reactant will be left after the reaction is complete? (4 points)
6
Chemistry 130
Exam #3 - A
December 6, 2010
21. A 14.25 mL sample of a Ca(OH)2 solution is titrated with 0.3651 M HCl. The balanced
equation for the titration reaction is shown below.
Ca(OH)2(aq) + 2HCl(aq)Æ 2H2O(l) + CaCl2(aq)
a.) If the titration requires 28.65 mL of the HCl solution to reach the equivalence point, how
many moles of Ca(OH)2 were in the original Ca(OH)2 solution? (7 points)
b.) If the end point of the titration was dark pink in color, would the value for the calculated
molarity be too large, too small, or unaffected? (2 points)
22. What is the condensed electron configuration of Sn4+? (3 points)
23. What is the condensed orbital box diagram for Ti? (3 points)
7
Chemistry 130
Exam #3 - A
8
December 6, 2010
Chemistry 130
Exam #3 - A
9
December 6, 2010
Chemistry 130
Exam #3 - A
10
December 6, 2010
Exam #3 - A
Chemistry 130
December 6, 2010
Conversion Factors, Constants, and Periodic Table
Avogadro’s Number:
6.022 x 1023 particles/mole
Pressure Conversion:
760 mmHg (torr) = 1 atm
Temperature conversion:
T [K] = 273.15 + T [°C]
Percent Yield:
Dilution:
% yield =
Compound
H2SO4
KC2H3O2
Molar Mass
98.079 g/mole
98.143 g/mole
actual yield
× 100%
theoretical yield
M1V1 = M2V2
1
2
H
He
1.0079
4.0026
3
4
5
6
7
8
9
10
Li
Be
B
C
N
O
F
Ne
6.941
9.0122
10.811
12.011
14.0067
15.9994
18.9984
20.1797
11
12
13
14
15
16
17
18
Na
Mg
Al
Si
P
S
Cl
Ar
22.9898
24.3050
26.9815
28.0855
30.9738
32.066
35.4527
39.948
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
K
Ca
Sc
Ti
V
Cr
Mn
Fe
Co
Ni
Cu
Zn
Ga
Ge
As
Se
Br
Kr
39.0983
40.078
44.9559
47.88
50.9415
51.9961
54.9380
55.847
58.9332
58.693
63.546
65.409
69.723
72.61
74.9216
78.96
79.904
83.80
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
Rb
Sr
Y
Zr
Nb
Mo
Tc
Ru
Rh
Pd
Ag
Cd
In
Sn
Sb
Te
I
Xe
85.4678
87.62
88.9059
91.224
92.9064
95.94
(98)
101.07
102.906
106.42
107.868
112.411
114.82
118.710
121.757
127.60
126.904
131.29
55
56
57
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
Cs
Ba
La
Hf
Ta
W
Re
Os
Ir
Pt
Au
Hg
Tl
Pb
Bi
Po
At
Rn
132.905
137.327
138.906
178.49
108.948
183.85
186.207
190.2
192.22
195.08
196.967
200.59
204.383
207.2
208.980
(209)
(210)
87
88
89
104
105
106
107
108
109
110
111
112
Fr
Ra
Ac
Rf
Db
Sg
Bh
Hs
Mt
(223)
226.025
227.028
(261)
(262)
(263)
(262)
(265)
(266)
114
116
Uun Uuu Uub
(269)
(272)
(277)
58
59
60
61
62
63
64
65
66
67
68
69
70
71
Ce
Pr
Nd
Pm
Sm
Eu
Gd
Tb
Dy
Ho
Er
Tm
Yb
Lu
140.12
140.908
144.24
(145)
150.36
151.96
157.25
158.925
162.50
164.930
167.26
168.934
173.04
174.967
90
91
92
93
94
95
96
97
98
99
100
101
102
103
Th
Pa
U
Np
Pu
232.038
231.036
238.029
(237)
(244)
Am Cm
(243)
(247)
11
Bk
Cf
Es
Fm
Md
No
Lr
(247)
(251)
(252)
(257)
(258)
(259)
(260)
(222)
118