Answer Key
Chem 10113, Quiz 3
September 16, 2015
IA
VIIIA
(1)
(18)
1
IIA
IIIA
IVA
VA
VIA
VIIA
He
1.0080
(2)
(13)
(14)
(15)
(16)
(17)
4.0026
3
4
5
6
7
8
9
10
Li
Be
B
C
N
O
F
Ne
6.9410
9.0122
10.811
12.011
14.007
15.999
18.998
20.179
11
12
13
14
15
16
17
18
Na
22.990
2
3
2
H
1
4
IVB
VB
VIB
24.305
(3)
(4)
(5)
(6)
VIIB
. . . . . . . . . . VIIIB . . . . . . . . .IB
.
(7)
(8)
(9)
(10)
(11)
IIB
Al
Si
P
S
Cl
Ar
(12)
26.982
28.086
30.974
32.066
35.453
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
83.800
39.098
5
Mg
IIIB
69.723
72.610
74.922
78.960
79.904
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
131.29
85.468
6
114.82
118.71
121.75
127.60
126.90
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
204.38
207.20
208.98
208.98
209.99
222.02
132.91
87
Fr
7
40.078 44.956 47.880 50.942 51.996 54.938 55.847 58.933 58.690 63.546 65.380
223.02
87.620 88.906 91.224 92.906 95.940 98.907 101.07 102.91 106.42 107.87 112.41
137.33 138.91 178.49 180.95 183.85 186.21 190.20 192.22 195.09 196.97 200.59
88
89
Ra
Ac
104
Unq
105
Unp
106
Unh
107
Uns
226.03 227.03 261.11 262.11 263.12 262.12
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
164.93
167.26
168.93
173.04
174.97
140.12 140.91 144.24 145.91 150.36 151.97 157.25 158.93 162.50
90
91
92
93
94
Th
Pa
U
Np
Pu
95
96
Am Cm
97
98
99
100
101
102
103
Bk
Cf
Es
Fm
Md
No
Lr
252.08
257.10
258.10
259.10
260.11
232.04 231.04 238.03 237.05 244.06 243.06 247.07 247.07 242.06
1.
SHOW ALL WORK. A certain organic amine is found to have the following percentage
composition by mass: 60.83 % C, 8.75 % H, and 30.41 % N. Determine the empirical formula of
this compound.
(6 points)
(60.83 g C) (1 mole C / 12.01 g) = 5.065 mole C
(8.75 g H) (1 mole H / 1.008 g) = 8.681 mole H
(30.41 g N) (1 mole N / 14.007 g) = 2.171 mole N
C5.065 H8.681 N2.171 = C5.065/2.171 H8.681/2.171 N2.171/2.171
= C2.33 H4.00 N
2.
(2 points)
(x 3) = C7H12N3
Write a complete, balanced chemical equation for the combustion of ethanol, C2H5OH.
C2H5OH
+
3 O2
→
2 CO2
+
3 H2O
3.
Complete the following table of compound names and formulas.
(9 points)
Formula
Name
As2S5
diarsenic pentasulfide
Sn(S2O3)2
tin(IV) thiosulfate
HBrO4(aq)
perbromic acid
.
4.
Mg3(PO4)2 4H2O
magnesium phosphate tetrahydrate
XeO3
xenon trioxide
Cs2Cr2O7
cesium dichromate
H2Se(aq)
hydroselenic acid
Al2(CO3)3
aluminum carbonate
Hg(CN)2
mercury(II) cyanide
Write a complete, balanced chemical equation for the production of barium nitrite by a
neutralization reaction.
(2 points)
Ba(OH)2
5.
+
2 HNO2
→
Ba(NO2)2
+
2 H2O
SHOW ALL WORK. The sulfide of a certain metal is thought to have the formula
M2S5. A 2.500 g sample of this compound is found to contain 0.04767 mole S. Identify the metal
M by determining its atomic mass.
(6 points)
mass of S = (0.04767 mole S) (32.066 g / mole) = 1.529 g S
mass of M = 2.500 g - 1.529 g = 0.9714 g M
moles of M = (0.04767 mole S) (2 mole M / 5 mole S) = 0.01907 mole M
molar mass of M (i.e., g/mole) = 0.9714 g / 0.01907 mole = 50.94 g/mole
∴ M = V (vanadium)