Chemistry 106: General Chemistry
Syracuse University Project Advance
Exam #3, Fall 2006
Name
Date
The last pages of the exam are reference tables.
1) The molecule POCl3 has bonding that is similar to that of the phosphorus atoms in
almost all biological molecules. Write the Lewis structure for POCl3, assuming P is
in the center of the molecule, with the requirement that every atom gets an octet of
electrons. The formal charge on P is:
a)
b)
c)
d)
e)
-2
-1
0
+1
+2
2) Write a Lewis formula for the nitrite ion, NO2-. Make sure that 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)
1
2
3
4
5
3) From a consideration of the Lewis structure of the thiocynate ion SCN-, in which
carbon has a double bond with both the sulfur and nitrogen atoms, the formal charges
on the sulfur, carbon, and nitrogen atoms are, respectively,
a)
b)
c)
d)
e)
-2, +1, 0
0, 0, -1
-2, 0, +1
-1, 0, 0
-1, +1, -1
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4) Which of the following has a Lewis structure most like that of NO-?
a)
b)
c)
d)
e)
NO+
O22O2O2
NO
5) A bond in which an electron is unequally shared by two atoms is
a)
b)
c)
d)
e)
coordinate covalent
dipolar
polar covalent
nonpolar covalent
ionic
6) In the Lewis structure of ClF3, the number of lone pairs of electrons around the
central atom is
a)
b)
c)
d)
e)
0
1
2
3
4
7) Which of the following statements about resonance is/are correct?
I. When resonance exists, a single Lewis structure does not adequately represent
the bonding.
II. Resonance describes a more stable situation than does any one contributing
structure.
III. When resonance exists, the formal charges on all the atoms in the molecule
are equal to zero.
a)
b)
c)
d)
e)
I and II
II and III
I and III
All are correct
None are correct
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8) Write the Lewis electron-dot formula for CO2 and use it to predict the shape or
geometry of this molecule using the VSEPR model.
a)
b)
c)
d)
e)
Bent (angular)
Linear
Tetrahedral
Trigonal Planar
Trigonal Pyramidal
9) Which of the following is/are correct?
I. The core electronic configuration of the ground state of the cobalt atom is
1s22s22p63s23p6.
II. The valence shell electronic configuration of the ground state of the bromine
atom is 4s24p5.
III. The complete ground state electronic configuration of the manganese atom is
1s22s22p63s23p63d54s2.
a)
b)
c)
d)
e)
I and II
I and III
II and III
All are correct
None are correct
10) Write the Lewis electron-dot formula for NF3 and use it to predict the shape or
geometry of this molecule using the VSEPR model.
a)
b)
c)
d)
e)
11)
Bent (angular)
Tetrahedral
Trigonal Planar
Trigonal Pyramidal
Linear
What hybrid orbitals of sulfur are involved in the bonding in sulfur trioxide?
a)
b)
c)
d)
e)
sp
sp2
sp3
dsp3
d2sp3
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12) Which of the following species has a bond order of 2.5?
a)
b)
c)
d)
e)
NOO22O2O2
O2+
13) According to the VSEPR model, the molecule COF2 (C in the middle) is:
a)
b)
c)
d)
e)
linear
square planar
pyramidal
trigonal planar
zig-zag
14) The nitrosyl ion, NO+, has ten bonding electrons and four antibonding electons.
Therefore, it has a bond order of
a)
b)
c)
d)
e)
5/2
1
2
7
3
15) In the ICl4- ion, the electron pairs are arranged around the central iodine in the shape
of
a)
b)
c)
d)
e)
an octahedron
a tetrahedron
a trigonal bipyramid
a trigonal pyramid
a square plane
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16) Which of the following molecules has/have sp3 hybrid orbital on the central atom(s)?
I. CH4
II. BF3
III. H2O
IV. H2C=CH2
V. NH3
a)
b)
c)
d)
e)
II and IV
I and III
I, II and V
I, II and III
I, III and V
17) A  (pi) bond is the result of:
a)
b)
c)
d)
e)
overlap of twp sp2 hybrid orbitals
overlap of two p orbitals along their axes
sidewise overlap of two parallel p orbitals
overlap of two s orbitals
overlap of an s and a p orbital
18) An ionic bond involves overlapping orbitals of the ions that compose it.
a)
b)
c)
true
false
depends upon the compound.
19) Which of the following does not describe a covalent bond.
a)
b)
c)
d)
e)
a bond which involves overlapping orbitals of the atoms that compose it.
a bond in which the electrons are attracted simultaneously to both positive
nuclei forming the bond.
a bond between a 1s orbital on hydrogen and a singly-occupied 2p orbital on
fluorine.
a bond symbolized by the line in H-Br.
a bond in the chlorine molecule, Cl2, formed by sharing of the 1s orbitals on
each of the chlorine atoms.
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20) The density of a gas is 3.48 g/L at STP. What is its molecular weight?
a)
b)
c)
d)
e)
44.6 g/L
224 g/L
78.0 g/L
32.0 g/L
147 g/L
21) A given mass of a gas occupies a volume of 4.00 L at 60° C and 550 mm Hg. Which
of the following mathematical expressions will yield its pressure at 3.00 L and 30° C?
a)
550 x
b)
550 x
 c)
550 x
 d)
550 x
 e)
550 x
4.00
3.00
3.00
4.00
3.00
4.00
4.00
3.00
3.00
4.00
x
x
x
x
x
303
333
303
333
30
60
30
60
333
303

22)We collected 20.0 L of CO2 at a pressure of 1 atm, T = 23° C. What is the volume of
the gas if T is increased to 30° C?
a)
b)
c)
d)
e)
15.3 L
19.5 L
20.0 L
20.5 L
26.1 L
23) 20.0 L of CO2 is contained in a tank at 23° C and 1.00 atm pressure. Gas is allowed
to escape from the tank slowly (keeping the temperature constant) until the pressure
drops to 0.50 atm. How many moles of gas are left in the tank?
a)
b)
c)
d)
e)
0.000873 mol
0.00175 mol
0.411 mol
0.823 mol
0.870 mol
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24) Real gases deviate from the ideal gas law at high pressures because
a)
b)
c)
d)
e)
the pressure causes the paths of the molecules to deviate from straight lines.
the gas becomes non-uniform due to convection currents
increasing the pressure makes the temperature increase.
molecules react with each other to form larger molecules
the molecules get close enough together so that intermolecular forces are
important.
25) Two 3.0 L sealed flasks, each at a pressure of 940 mmHg are in a room. One
contains He and the other Ar. If the flask containing Ar is heated:
a)
b)
c)
d)
e)
then the flask containing Ar would be at a lower pressure than the flask
containing He.
then the flask containing Ar would be at a higher pressure than the flask
containing He.
there is insufficient information to draw a conclusion about the relative
pressures of the two flask.
the two flasks would be at the same pressure.
None of the above.
26) A sample of oxygen gas occupies a volume of 900 mL at a pressure of 100 mmHg.
What is the pressure of the gas if the volume is reduced to 300 mL and the
temperature is doubled?
a)
b)
c)
d)
e)
27)
66.7 mmHg
33.3 mmHg
300 mmHg
150 mmHg
600 mmHg
If 4 mol of Neon gas and 6 mol of Krypton gas are contained in a flask whose
total pressure is 1000 mmHg, the partial pressure of the Neon gas would be:
a)
b)
c)
greater than the partial pressure of the Krypton gas.
less than the partial pressure of the Krypton gas.
same as the partial pressure of the Krypton gas.
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EC) Ammonium Nitrite undergoes decomposition to produce only gases as shown
below:
NH4NO2 (s)  N2 (g) + 2 H2O (g)
How many TOTAL liters of gas will be produced by the decomposition of 35.0 g of
NH4NO2 (s) at 525oC and 1.5 atm? (SHOW ALL WORK)
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