Exam 2 – Version B
Course:
Instructor:
Chemistry 100
Armando Herbelin x2882
aherbelin@lcc.ctc.edu
Calculator is OK, No notes.
85 min.
Proctoring:
Time Limit:
Winter 2003
Name: _Key____________________
Be sure to show your work and include units for any calculations.
1A
1
1
H
H
1.008
1.008
2.1
3
2A
4
Li
8A
2
Atomic Number
Symbol
Atomic Mass
Pauling’s Electronegativity
2.1
He
4.003
3A
5
4A
6
5A
7
6A
8
7A
9
10
Be
B
C
N
O
F
Ne
6.941
9.012
10.81
12.01
14.01
15.99
19.00
20.18
1.0
11
1.5
12
2.0
13
Al
2.5
14
Si
3.0
15
P
3.5
16
S
4.0
17
Cl
26.98
28.09
30.97
32.07
35.45
1.5
1.8
2.1
2.5
3.0
Na Mg
22.99
24.31
0.9
19
1.2
20
K
Ca
39.10
40.08
0.8
37
1.0
38
Rb
Sr
85.47
87.62
0.8
55
0.9
56
Cs
Ba
132.9
137.3
0.7
87
0.9
88
Fr
Ra
(223)
226.0
*
Lanthanide
Series
†
Actinide
Series
1s
2s 2p
3s 3p 3d
4s 4p 4d 4f
5s 5p 5d 5f
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
44.96
47.88
50.94
52.00
54.94
55.85
58.93
58.69
63.55
65.39
69.72
72.61
74.92
78.96
79.90
1.8
1.8
2.0
2.4
2.8
39
Y
88.91
40
Zr
91.22
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
92.91
95.94
(99)
101.1
102.9
106.4
107.9
112.4
114.8
118.7
121.8
127.6
126.9
1.7
1.8
1.9
2.1
2.5
81
Tl
82
Pb
83
Bi
84
Po
85
At
204.4
207.2
209.0
(209)
(210)
1.8
1.9
1.9
2.0
2.2
68
69
70
71
57
La
72
Hf
73
Ta
138.9
178.5
180.9
*
89
Ac
†
227.0
74
75
76
77
78
W
Re
Os
Ir
Pt
183.9
186.2
190.2
192.2
195.1
197.0
200.6
107
108
109
65
66
67
104
105
Rf
Db Sg
Bh Hs Mt
(261)
(262)
(263)
(262)
(265)
(268)
60
61
62
63
64
58
59
Ce
Pr
140.1
140.9
106
79
80
Au Hg
Nd Pm Sm Eu Gd Tb Dy Ho
144.2
90
91
92
Th
Pa
U
232.0
231.0
238.0
(145)
150.4
152.0
157.3
158.9
93
94
95
96
97
162.5
Er Tm Yb Lu
164.9
167.3
168.9
173.0
175.0
100
101
102
103
98
99
Np Pu Am Cm Bk
Cf
Es Fm Md No
Lr
237.0
(251)
(252)
(260)
(244)
HONClBrIF
D=m/V
V=r3=(d/2)3
(243)
(247)
(247)
5280 ft = 1 mi
1 lb = 454 g
1 in = 2.54 cm
1 gal = 3.785 L
2.20 lb = 1 kg
(257)
(258)
(259)
2.54 cm = 1 in
1 cm3 = 1 mL
K=°C+273.15
°C=5/9(°F - 32)
°F=9/5(°C) + 32
18
Ar
39.95
36
Kr
83.80
54
Xe
131.3
86
Rn
(222)
1. (10 pts) Draw lines to match the geometric form (center column) with its name (left column)
and any molecules that have its form. Some items may not have matches.
Note: The circles in the geometric forms are not oxygens – they’re atoms.
#
Shape Name
a
Bent
b
Equilateral
Cl2
c
Tetrahedral
H2O
d
Oriental
CF4
e
Linear
CO2
Shape
Picture
Chemical
Example
(-1) for any lines to oriental or equilateral
2. (4 pts) In the space below, write the name of each chemical from #1.
b
c
d
e
chlorine, dichloride
water, dihydrogen monoxide
carbon tetrafluoride
carbon dioxide
____/14
3. (8 pts) Write the formulas for the five “normal” oxyacids that we memorized then fill in the
rest of the table.
Element
Formula
Name
# of
Oxygens
# of
Hydrogens
N
HNO3
Nitric Acid
3
1
C
H2CO3
carbonic acid
3
2
P
H3PO4
phosphoric acid
4
3
Cl
HClO3
chloric acid
3
1
S
H2SO4
sulfuric acid
4
2
4. (5 pts) Write the name and formula of the five acids (with or without oxygen) of chlorine.
HClO4
HClO2
HCl
perchloric acid
chlorous acid
hyrdochloric acid
HClO3
HClO
chloric acid
hypochlorous acid
5. (2 pts) Write the chemical formula for the two ions of Iron.
Fe2+, Fe3+
6. (4 pts) Write all four possible names for Copper ions (new and old system).
Copper (I) ion, Copper(II) ion, cupric ion, cuprous ion
7. (5 pts) Write the chemical formula of Ferric sulfide.
(Fe3+ & S2-)
Fe2S3
8. (10 pts) A cold day in Alaska (according to the fiction of Jack London, not fact) can be 100
below meaning -100F. What is this temperature in Kelvin?
Show your work – including the equations that you will use.
°C=5/9(°F-32)=5/9(-100-32)=5/9(-132) = -73.33
K = °C + 273.15 = -73.33 + 273.15 = 199.8 K (sig fig rules not enforced)
____/19
9. A student measure diameter (5.9 cm) of a sphere with unknown chemical composition and
calculates the volume (You don’t have to calculate volume!).
3
3
4
4 d
4  5.9cm 
3
V  r 3       
  107.536 cm
3
3 2
3  2 
a. (4 pts) What is the volume in mL?
1 mL= 1 cm3, volume is 107.536 mL
b. (4 pts) If the mass is determined to be 18.32 g, what is the sphere’s density?
D = m/V = 18.32 g / 107.536 mL = 0.1703 g/mL
c. (2 pts) Will it float in water? WHY?
YES, because the density is less than 1 g/mL, the density of water.
10. (5 pts). Draw the Lewis dot structure and write the chemical formula for carbon
tetrabromide.
CBr4 (2 pts)
Atom Electrons
C
1x4=4
Br
4 x 7 = 28
Total 32

Electronegativity
2.5 (center)
2.8





Br




Br

C

Br




 Br





11. (5 pts). Draw the Lewis dot structure and write the formula of carbon dioxide.
CO2 (2 pts)
Atom Electrons
C
1x4=4
O
2 x 6 = 12
Total 16
Electronegativity
2.5 (center)
3.5



13. (5 pts). How many oxygen atoms are in C15H14O5?
5,
O


C


O



CH3COOH?
2
____/15
____/25
14. Molecular Geometry with CH2Cl2.
a. (5 pts.) Draw the Lewis structure of CH2Cl2 (2-dimensional picture)
H
Atom Electrons
Electronegativity
C
1x4=4
2.5 (center)
or
Cl
2 x 7 = 14
3.0

 Cl 
H
2x1=2
2.1 (never in center)


Total 20


H  C  Cl


H
H



 Cl 
C  Cl 






b. (5 pts) Add dipoles to the 3D Ball & Stick picture. What is the net dipole for this
molecule?
(net dipole is dotted)
Bonus: (5 pts) Briefly explain why the 2-D models might give the wrong answer for net dipole.
With the 2D model (Lewis Diagram), you might place the Cl atoms across from each other,
canceling the dipoles. In 3D (and real life) there is not way for this to happen.
____/10
15. (10 pts) Fill in the following table. Bond type is Covalent, Polar Covalent, or Ionic.
Chemical Name
Chemical Formula
Dinitrogen tetroxide
N2O4
Water, dihydrogen
monoxide
H2O
Hydrogen fluoride
HF
Aluminum oxide
Al2O3
potassium fluoride
KF
Bond Type
(polar) covalent
polar covalent
polar covalent
ionic
ionic
16. (2 pts) What element is present in all of the acids?
Hydrogen
17. (5 pts) How many minutes are there in March? (31 days) Show your work!
 24hr  60 min

31days  
 1day  1hr

  44640 min

2 points for calculating seconds.
____/17