Module 1 Quiz Practice Questions
Sourced from Chem 131 F2017 Exam 1
1. An element has two naturally occurring isotopes. Isotope 1 has a mass of 120.9038 amu
and a relative abundance of 57.4%. Isotope 2 has a mass of 122.9042 amu. Calculate
the atomic mass of the atom and identify the atom from the periodic table.1 (15pts)
2. b-hydroxybutyrate is a nutritional supplement used by people following a ketogenic
diet and is composed of carbon, oxygen, and hydrogen. A sample of 10.00 g of bhydroxybutyrate is burned completely in the presence of excess oxygen and 16.94 g of
CO2 and 6.930 g of H2O is isolated. Assume 100 % yield of the combustion reaction. The
unbalanced reaction is given below:
! − ℎ$%&'($)*+$&,+- + /! → 1/! + 2! /
a. Provide an empirical formula for b-hydroxybutyrate. (10 pts)
b. **Note: This information requires use of concentration concepts from Module 2
and would not be asked in this way for a Module 1 quiz.**
To a container was added 10 mL of b-hydroxybutyrate (1.041 g/mL). Water
was added until the total volume was 100 mL. This solution had a
concentration of b-hydroxybutyrate of 1.00 M. What is the molecular weight
and molecular formula of b-hydroxybutyrate? (10 pts)
1
Adapted from Tro, Principles of Chemistry, A Molecular Approach, 2nd edition
1
PERI ODI C TABLE OF THE ELEM ENTS
2
7
O
8
F
9
Ne
He
6
N
18
20.18
H
5
C
17
19.00
10
4
B
16
16.00
4.00
3
Be
15
14.01
1.008
Li
14
12.01
Ar
13
Cl
10.81
S
12
P
9.01
Si
11
Al
6.94
Mg
Kr
Na
Br
36
Se
39.95
As
35
30
Ge
35.45
29
Ga
34
28
Zn
32.06
27
Cu
33
26
Ni
30.97
25
Co
32
24
Fe
28.09
23
Mn
31
22
Cr
26.98
21
V
20
Ti
24.30
Sc
19
Ca
22.99
K
Xe
54
131.29
83.80
I
53
126.91
79.90
Te
52
127.60
78.96
Sb
51
121.75
74.92
Sn
50
118.71
72.59
In
49
114.82
69.72
Cd
48
112.41
65.39
Ag
47
107.87
63.55
Pd
86
46
106.42
Rn
58.69
Rh
85
(222)
45
102.91
At
58.93
Ru
84
(210)
44
101.1
Po
55.85
Tc
83
(209)
43
(98)
82
Bi
54.94
Mo
81
208.98
42
95.94
80
Pb
52.00
Nb
79
207.2
41
92.91
78
Tl
50.94
Zr
77
204.38
40
91.22
76
Hg
47.90
Y
75
200.59
39
88.91
74
Au
44.96
Sr
73
196.97
38
87.62
72
Pt
40.08
Rb
57
195.08
37
85.47
56
Ir
39.10
55
192.2
71
Os
Lu
190.2
70
174.97
Re
Yb
186.21
69
173.04
W
Tm
183.85
68
168.93
103
Ta
Er
Lr
180.95
67
167.26
102
(262)
Hf
Ho
No
178.49
Rg
66
164.93
101
(259)
* La
(272)
Dy
100
(258)
Md
138.91
Ds
65
162.50
Fm
Ba
(271)
Tb
99
(257)
137.33
Mt
64
158.93
Es
Cs
(268)
Gd
98
(252)
132.91
Hs
63
157.25
Cf
111
(277)
Eu
97
(251)
110
Bh
62
151.97
Bk
109
(2624
Sm
96
(247)
108
Sg
61
150.4
95
(247)
Cm
107
(266)
Pm
94
(243)
Am
106
Db
60
(145)
Pu
105
(262)
Nd
93
(244)
104
Rf
59
144.24
Np
89
(261)
Pr
92
(237)
88
58
140.91
U
87
227.03
Ce
91
238.03
Ra
140.12
Pa
226.02
90
231.04
Fr
Th
(223)
*Lanthanide Series
232.04
Formulas
!" = −log [" ! ]
5
!," = −log [," ]
Units and Constants
+" = +#!" +$"#
!
5
+" = [" ][," ]
[HA]
[HA]
!,"
=
!+
+
log
$
[/ 5 ]
[/5]
5
[A ]
[A5 ]
!" = !+# + log
!," = !+$ − log
["/]
["/]
!" = !+# − log
LM = N>O
P3,* + P3,*+$
P2 =
2
[2+ ] = [2, /+ ] = 10#-.
3/0
1 1*
= 3- S T
>O
L& = H& L'('&)
1=
2344 6(89 )
=
5
;<
NAvogadro = 6.022 × 1023
1 mL = 1 cm–3; 1000 L = 1 m3
3" = 1.0 • 10#$%
1000 mL = 1 L
1000 g = 1 kg
1000 mg = 1 g
0 °1 = 2733
,+@ • A
@'B • 3
D
> = 8.314
@'B • 3
> = 0.0821
1 '() = 760 ./00 = 760 ))12 = 101 34'
1D =1
EF • @!
G!
−) ± √) ! − 4,K
H=
2,
3-U