1
Exam 3
CHEM 1303.001
Name (print legibly)___________________________________________Seat no.__________
On my honor, I have neither given nor received unauthorized aid on this exam.
Signed
_______________Date ________________
Part 1. Multiple choice (use answer card). 22 questions. 3 points each.
Indicate the BEST answer for the questions in this section by completely filling in the
appropriate space on the answer card with a #2 pencil. Mark only one space per question.
1.
Which of the following should have the lowest first ionization energy?
a.
b.
c.
d.
e.
2.
Li
Be
Mg
Ca
K
Which of the following should have the greatest second ionization energy?
a.
b.
c.
d.
e.
3.
Li
Be
B
Ca
C
Of the following oxides, which is/are acidic?
Li2O
CaO
SO3
Cl2O7
a.
b.
c.
d.
e.
4.
Li2O only
SO3 only
Li2O and CaO
CaO and SO3
SO3 and Cl2O7
Which of the following should have the greatest lattice energy?
a.
b.
c.
d.
e.
KCl
CaO
KF
NaF
NaBr
2
5.
Which of the following would you expect to have the most polar bond?
a.
b.
c.
d.
e.
N2
OF
NF
O2
CF
Consider the species PF4–. P is the central atom. The hybridization of P is
6.
a.
b.
c.
d.
e.
7.
sp
sp2
sp3
sp3d
sp3d2
Which of the following has polar bonds and an overall zero dipole moment?
a. F
H
C C
H
F
b. F
F
a. is answer
C C
H
H
c. CO
d. F2
e. Ar
8.
The F–Xe–F bond angle (in degrees) in XeF4 is closest to
a.
b.
c.
d.
e.
9.
75
90
109.5
115
120
Which of the following is an ionic compound?
a.
b.
c.
d.
e.
RbCl
PF5
BrF3
CI4
H2O
3
10.
Consider the reaction
H
H C O (g)
2H(g) + C(g) + O(g)
ΔHo = +1,573 kJ
The average bond energy of the C–H bond is 414 kJ/mol. Calculate the average bond
energy of the C=O bond (in kJ/mol).
a.
b.
c.
d.
e.
11.
1,159
2,401
331
745
1,987
The number of resonance structures that satisfy the octet rule for S in SO2 is
a.
b.
c.
d.
e.
12.
0
1
2
3
4
A solid that lacks a regular three-dimensional array and lacks long-range order is best
classified as a(n)
a.
b.
c.
d.
e.
13.
covalent crystal.
metallic crystal.
ionic crystal.
molecular crystal.
amorphous solid.
A solid is hard, brittle, and electrically nonconducting. Its melt, and an aqueous
solution containing the substance, conducts electricity. The solid is best classified as
a(n)
a.
b.
c.
d.
e.
14.
covalent crystal.
metallic crystal.
ionic crystal.
molecular crystal.
amorphous solid.
The lattice points in a covalent crystal are occupied by
a.
b.
c.
d.
e.
molecules.
cations only.
cations and anions.
atoms.
anions only.
4
For questions 15 – 17, consider the following intermolecular forces:
i.
ii.
iii.
iv.
v.
15.
ion-dipole
dipole-dipole
dipole-induced dipole
(London) dispersion
hydrogen-bonding
The primary force responsible for the dissolving of KCl in water is
a.
b.
c.
d.
e.
16.
i
ii
iii
iv
v
The boiling points of the following compounds increase in the order
H2S < H2Se < H2Te. The primary force responsible for this is
a.
b.
c.
d.
e.
17.
i
ii
iii
iv
v
What types of intermolecular forces would be present in the pure liquid form of the
compound
H H
H
H C C O C H
H H
a.
b.
c.
d.
e.
18.
H
only i, ii, and iii
only ii and iv
only i, iv, and v
only ii, iv, and v
only iii and v
Which of the following is the most polarizable?
a.
b.
c.
d.
e.
H2
H2O
H2S
H2Se
H2Te
5
19.
An element crystallizes in a face-centered cubic lattice. The unit cell has an edge
length of 407 pm. The radius (in pm) of an atom of this element is
a.
b.
c.
d.
e.
20.
204
144
102
288
175
The sketch below is for a molecular orbital in a homonuclear diatomic molecule.
Which one is it? The internuclear axis is the x axis.
x
a.
b.
c.
σ1s
π2px
π∗2p
x
d.
e.
σ∗2px
σ2px
For questions 21 – 22, use the
diagram at right as an aid.
Energy
6
2p
2p
!*2s
2s
2s
!2s
21.
Which of the following species will be paramagnetic?
N2
N2–
N22–
a. N2 only
b. N – only
2
c. N and N 2–
2
2
d. N – and N 2–
2
2
e. All are paramagnetic.
22.
Which of the following correctly lists species in order of increasing bond length?
a. C < C + < C –
2
2
2
b. C – < C < C +
2
2
2
c. C – < C + < C
2
2
2
d. C < C – < C +
2
2
2
e. C + < C < C –
2
2
2
Part 2. 4 questions. 34 points total.
1. (6 pts) Describe two unusual properties of water that are explained by hydrogen-bonding.
Write a sentence or two to describe each property and how hydrogen-bonding accounts for it.
See text and notes for answers.