Name: _________________________
Mock Exam 4
Multiple choice (5 percent each, no partial credit)
1. Which statements are true?
X. All group 13 elements (i.e. B, Al, Ga, …)
must achieve an electron octet.
Y. Main group elements gain, lose or share
electrons to achieve a noble-gas
electron configuration.
Z. Elements in rows 3, 4, 5, … are able to
accommodate more than an octet.
a. X and Z
b. X and Y
c. Y only
d. Y and Z
e. Z only
2. What is the density of N2O(g) at 1140 torr
and 54.0 °C?
a. 2.46 g/L
b. 0.964 g/L
c. 154 g/L
d. 0.407 g/L
e. Not enough information to solve
3. What is the name of the molecule shown?
a.
b.
c.
d.
e.
Meta-tribromobenzene
1,3,5-tribromobenzene
Tri-meta-bromobenzene
2,4,5-tribromobenzene
1,2,3-tribromobenzene
4. An sp3d2 hybridized atom has how many
regions of electron density?
a. 6
b. 5
c. 4
d. 3
e. 2
5. A 13.2 L sample of gas initially at 1.40 atm
and 26.0 °C, is simultaneously heated to
182 °C and compressed to 3.90 L. What is
the final pressure?
a. None of the others
b. 33.2 atm
c. 2.90 atm
d. 3.11 atm
e. 7.21 atm
6. Which of the following molecules have
bond angles of 109.5°?
XeF4
SF4
CF4
a. SF4 and XeF4
b. SF4 only
c. XeF4 only
d. CF4 only
e. CF4 and SF4
7. Which statements are false?
X. A C=C bond is shorter than a C≡C bond
Y. It takes more energy to break an N=O
bond than an N-O bond
Z. In a triple bond, 4 electrons are shared
between two atoms.
a. X only
b. Y only
c. X and Z
d. X and Y
e. Y and Z
8. What is the molecular geometry for BrF3?
a. Triangular pyramidal
b. Bent
c. Triangular planar
d. T-shaped
e. Triangular bipyramidal
9. Which molecule should have the weakest
intermolecular interactions?
a.
b.
c.
d.
e.
10. Which would you predict to be the longest
bond?
a. C-O
b. O-F
c. C-F
d. N-O
e. C-N
11. Which statements are true?
X. Single, double and triple bonds each
have a σ-bond in them.
Y. When atomic orbitals that are oriented
perpendicular to the bond axis overlap,
they create a σ-bond.
Z. The idea that overlap of atomic orbitals
creates covalent bonds comes from
valence bond theory.
a. Y and Z
b. X and Z
c. X and Y
d. X only
e. Z only
12. What is the formal charge on the sulfur in
SO32-?
a. -2
b. 0
c. 1
d. 3
e. 5
13. Calculate the total pressure of a mixture of
3.45 mol N2(g), 2.35 mol O2(g) and 1.25 mol
of CO2(g) in a 23.0 L container at 25.0 °C.
a. 7.50 atm
b. 0.629 atm
c. Not enough information
d. 1.06 atm
e. 13.0 atm
14. Calculate the ΔH for the following reaction.
C2H4(g) + O2(g) → CO2(g) + H2O(g)
a. 220 kJ
b. -1028 kJ
c. -1324 kJ
d. None of the others
e. -630 kJ
15. Find the partial pressure of He(g) in a
mixture of 3.82 mol He(g), 4.12 mol Ne(g),
and 1.24 mol Ar(g) if the total pressure is
900 mm Hg.
a. 1.18 atm
b. 0.493 atm
c. 0.531 atm
d. 0.160 atm
e. None of the others
16. What mass of C2H2(g) is necessary to
completely react with 24.2 L of O2(g) at
STP?
a. 34.5 g
b. 11.2 g
c. None of the others
d. 28.1 g
e. 26.0 g
Fill-in-the-blank (2 percent per blank, no partial credit)
CH2O
Write the Lewis structure
(include resonance structures if any)
Draw the structure
(using wedges & dashed-wedges)
Write the electronic geometry (central atom)
Write the molecular geometry
Triangular planar
Triangular planar
List all intermolecular forces (if any)
London forces & dipole-dipole
SO2
Write the Lewis structure
(include resonance structures if any)
Draw the structure
(using wedges & dashed-wedges)
Write the electronic geometry (central atom)
Write the molecular geometry
Triangular planar
Bent
List all intermolecular forces (if any)
London forces & dipole-dipole
Useful information
Average Bond Enthalpies (in kJ/mol)
Single bonds
H
C
N
O
F
Si
P
S
Cl
Br
I
I
299
213
--201
--234
184
--209
180
151
Br
366
285
------310
264
213
217
193
Cl
431
327
193
205
255
391
319
255
242
S
347
272
----326
226
--226
P
322
264
~200
~340
490
--209
Si
323
301
335
368
582
226
F
566
486
272
190
158
O
467
336
201
146
N
391
285
160
Multiple bonds
N=N
N≡N
C=N
C≡N
418
946
616
866
O=O (in O2)
498
Physical constants
Ideal gas constant: R = 0.08206 L·atm / K·mol
Ideal gas constant: R = 8.314 J / K·mol
C=C
C≡C
C=O (as in CO2)
C=O (as in
H2C=O)
C≡O
598
813
803
695
1073
C
416
356
H
436