Chemistry 106: General Chemistry
Syracuse University Project Advance
Exam #3, Fall 2005
Name
Date
The last pages of each examination are reference tables.
R = 0.08206 L*atm/mole*K
1)
The ground-state electron configuration of S is [Ne]3s23p4, which implies there
are two unpaired electrons and S can form two bonds. However, the Lewis
structure of SF6 shows six S-F single bonds. This can occur because
a) Electrons may be promoted into the 3d orbitals of S with a relatively small
energy cost
b) The 3s electrons may be promoted into the 4s subshell with a relatively
small energy cost.
c) All of the six electrons in the M shell (n = 3) can be unpaired with a very
small energy cost.
d) Electrons can be added to S from the fluorines, each of which has more
electrons than S.
e) Some of the electron pairs on S can be transformed into bond pairs.
2) Which of the following does not describe a covalent bond?
a) electrons are attracted simultaneously to both positive nuclei forming the
bond.
b) involves overlapping orbitals of the atoms that compose it.
c) sharing of core (inner) electrons.
d) all describe covalent bonds.
3) A correct Lewis Formula for P2 is:
a)
P
P
b)
P
P
c)
P
P
d)
P
e)
None of the above
CHE 106
P
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Fall 2005 Exam #3
4) Given the Lewis structure:
H O Cl
O
Calculate the formal charges for the designated atoms:
Oxygen bonded to H,
Cl
+1
-1
-1
0
0
a)
b)
c)
d)
e)
Cl
-1
+1
0
-1
+1
Oxygen bonded to
Cl
0
0
+1
+1
-1
5) Which of the following statements about resonance is/are incorrect?
I. When resonance exists, a single Lewis structure does not adequately represent the
bonding.
II. Resonance describes the vibration of nuclei within the molecule.
III. Resonance describes a bonding situation that is in between the contributing
structures.
a)
b)
c)
d)
e)
6)
I
II
III
I and III
none are incorrect
Write a Lewis formula for the ion AlF63-. (Al will have more than an octet around
it.) How many non-bonding electrons are there all together? (the entire atom not
just the central atom)
a)
b)
c)
d)
e)
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24
30
36
42
48
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Fall 2005 Exam #3
7) What could you do to improve the Lewis structure at right?
a)
b)
c)
d)
e)
8)
Write a Lewis formula for the nitrate ion, NO2-. Make sure the octet rule is
followed. What is the total number of bonds in your formula? (A double bond
counts as two bonds, a triple bond counts as three.)
a)
b)
c)
d)
e)
9)
1
2
3
4
5
The Lewis structure of acetic acid is shown at right. How many  (sigma) bonds
are there in the structure? (A bond involves one pair of electrons.)
a)
b)
c)
d)
e)
10)
Take one of the lone pairs off F and put it on H.
Remove one of the lone pairs from F.
Take one of the lone pairs of O and put it into the C-O bond, forming a
double bond C=O.
Take one of the C-F bonding pairs and make it a lone pair on C.
Take one of the C-F bonding pairs and put it into the C-O bond, forming a
double bond C=O.
1
3
5
7
8
H O
H C C
O H
H
The molecular geometry of PCl3 is
a)
b)
c)
d)
e)
CHE 106
linear
bent (or angular)
trigonal planar
trigonal pyramidal
tetrahedral
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Fall 2005 Exam #3
11)
The molecule of propenol has the bond structure at right. The hybridization on
the three carbons, from left to right, is
a)
b)
c)
d)
e)
12)
H
H–C–C=C–O-H
H
1 and 2
1 and 3/2
2 and 3/2
2 and 5/2
2 and 3
The order of filling of molecular orbitals in homonuclear diatomics is as follows:
1s < *1s < 2s < *2s < 2p < 2p < *2p < *2p
Derive the orbital diagrams for the following molecules: Be2, B2, and C2. Which
of these three molecules are paramagnetic?
a)
b)
c)
d)
e)
14)
H
The order of filling of molecular orbitals in homonuclear diatomics is as follows:
1s < *1s < 2s < *2s < 2p < 2p < *2p < *2p
The molecule of C2 has 12 electrons. The bond orders in C2 and n the anion C2are
a)
b)
c)
d)
e)
13)
sp3, sp3, sp
sp2, sp2, sp3
sp, sp2, sp3
sp2, sp, sp3
sp2, sp3, sp3
none of them
just Be2
just B2
just C2
B2 and C2
Suppose 3.15 L of neon at 21°C and P = 0.951 atm is compressed to 1.292 atm,
with the temperature held contant. The new volume is
a)
b)
c)
d)
e)
CHE 106
2.32 L
3.00 L
3.15 L
4.10 L
4.44 L
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Fall 2005 Exam #3
15)
A tank of volume 40 L contains a gas at 1.0 atm pressure, and a temperature of
20°C. Another tank, of volume 60 L, contains the same gas, also at 20°C, but at
2.0 atm pressure. The tanks are connected so gas can flow between them, with
the temperature maintained at 20°C. At equilibrium, the pressure is the same
everywhere in the total volume of 100 L. What is the final pressure?
a)
b)
c)
d)
e)
16)
What is the density of ammonia gas, NH3, at 31°C (304 K) and 0.988 atm
pressure? Molar mass of NH3 is 17.03 g/mol. R = 8.314 J mol-1 K-1 = 0.0820 L
atm mol-1 K-1.
a)
b)
c)
d)
e)
17)
1.4 atm
1.5 atm
1.6 atm
2.0 atm
3.0 atm
0.0396 g/L
0.675 g/L
0.691 g/L
6.61 g/L
16.8 g/L
Ammonium sulfate is produced by reacting ammonia with sulfuric acid,
according to: 2NH3(g) + H2SO4(aq)  (NH4)2SO4(aq). What volume of
ammonia gas at 15°C and 1.15 atm is required to produce 1.136 mol of
ammonium sulfate?
a)
b)
c)
d)
e)
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11.7 L
20.5 L
23.4 L
40.6 L
46.7 L
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Fall 2005 Exam #3
18)
Here are three statements about the molecules in an ideal gas.
I. The forces between molecules are almost always unimportant.
II. The average speed of a molecule is proportional to the temperature.
III. The kinetic energy of a molecule is unchanged if it collides with the container
wall.
Which of these statements are true, according to the kinetic-molecular theory of the
ideal gas?
a)
b)
c)
d)
e)
19)
Which of the following is/are characteristic of gases?
a)
b)
c)
d)
e)
20)
High compressibility
Relatively large distance between molecules.
Formation of homogeneous mixtures regardless of the natures of nonreacting gas components.
All of the above.
None of the above.
The average kinetic energy of molecules of a gas depends on
a)
b)
c)
d)
e)
21)
none of them
number I and II
number II and III
number I and III
all of them
the temperature of the gas.
the total mass of the molecules of the gas.
the density of the gas.
all of these.
none of these.
24.2 g of gas initially at 4.00 atm is compressed from 8.00 L to 2.00 L at constant
temperature. What is the resulting pressure (in atm) of the gas?
a)
b)
c)
d)
e)
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4.00
2.00
1.00
8.00
16.0
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Fall 2005 Exam #3
22)
A sample of hydrogen was collected by water displacement at 23.0°C and an
atmospheric pressure of 735 torr. Its volume is 568 mL. After water vapor is
removed, what volume would the hydrogen occupy at the same conditions of
pressure and temperature? (The vapor pressure of water at 23.0°C is 21 torr).
a)
b)
c)
d)
e)
23)

509 mL
539 mL
552 mL
568 mL
585 mL
Which one of the following is not possible for an ideal gas?
a)
V1 V2

T1 T2
b)
V1T1  V2T
c)
V1 T1

V2 T2
d)
V2 
e)
none of the above.


T2
V2
T1

24)
How many moles of gas occupy 60.82 L at 31°C and 367 mm Hg?
a)
b)
c)
d)
e)
CHE 106
1.18
0.850
894
11.6
0.120
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Fall 2005 Exam #3