Name: ______________________________
Chemistry 115-1C Exam 4
Multiple Choice (5 points each, no partial credit)
1. Which of the following statements are true?
A. When making Lewis structures, there
are no exceptions to the octet rule.
B. Elements seek to achieve a noble-gas
electron configuration in their valence
shell by gaining, losing or sharing
electrons.
C. You can use a Lewis structure to know
the 3-dimensional structure of a
molecule without using valence-shell
electron-pair repulsion theory.
a. A only
b. C only
c. B only
d. A and B
e. B and C
2. Calculate the ΔH for the combustion of
cyclopropane using the balanced chemical
equation. All of the molecules are gases.
2 C3H6 + 9 O2 → 6 CO2 + 6 H2O
a. -1594 kJ/mol
b. -3630 kJ/mol
c. 2921 kJ/mol
d. -2334 kJ/mol
e. None of the above
3. What is the formal charge on the central
atom in SO42- (sulfate anion)?
a. 2
b. 3
c. -1
d. 0
e. 1
4. Which of the following is the correct name
for the compound shown below?
a. 1,2,4-trichlorobenzene
b. Ortho-meta-trichlorobenzene
c. 1,3,5-trichlorobenzene
d. 1,2,3-trichlorobenzene
e. Ortho-trichlorobenzene
5. Predict the order of increasing bond length
Al-N
Al-O
Al-P
a. Al-P < Al-O < Al-N
b. Al-P < Al-N < Al-O
c. Al-O < Al-N < Al-P
d. Al-O < Al-P < Al-N
e. Al-N < Al-O < Al-P
6. Which resonance structure(s) would you
predict to contribute the least to the
resonance hybrid of N2O (nitrous oxide)?
A.
B.
C.
a.
b.
c.
d.
e.
A only
A and C
B and C
A and B
C only
7. What is the molecular geometry for SF42-?
a. Tetrahedral
b. See-saw
c. Square pyramidal
d. Triangular bipyramidal
e. Square planar
8. Predict the order of increasing bond angle
for the following molecules
GeH4
SeH2
AsH3
a. AsH3 < SeH2 < GeH4
b. GeH4 < AsH3 < SeH2
c. SeH2 < GeH4 < AsH3
d. GeH4 < SeH2 < AsH3
e. SeH2 < AsH3 < GeH4
9. What is the hybridization on the central
atom in ICl3 (iodine trichloride)?
a. sp
b. sp2
c. sp3
d. sp3d
e. sp3d2
10. Which of the following intermolecular
forces will methanol (CH3OH) exhibit?
A. London forces
B. Dipole-dipole
C. Hydrogen bonding
a. A only
b. A and B
c. B only
d. A and C
e. C only
11. A double bond consists of
a. Two single bonds
b. One σ-bond and one π-bond
c. Two σ-bonds
d. Two π-bonds
e. One σ-bond and two π-bonds
12. A gas is initially in a 3.13 L container at 1.56
atm. If the gas is transferred to a container
with a volume of 8.79 L, what is the new
pressure of the gas?
a. 0.555 atm
b. 17.6 atm
c. 4.38 atm
d. 8.82 atm
e. 3.63 atm
13. What is the pressure of N2 gas at 325 °C if it
has a density of 1.25 g/L?
a. 1.00 atm
b. Not enough information to answer
c. 1.19 atm
d. 4.38 atm
e. 2.19 atm
14. What is the volume of H2 produced from
the following reaction if 3.82 L of CH4(g)
react with 3.82 L of H2O(g).
CH4(g) + H2O(g) → CO(g) + 3 H2(g)
a. 11.5 L
b. 3.82 L
c. Not enough information to answer
d. 7.64 L
e. 22.9 L
15. According to the kinetic-molecular theory of
gases, which statements are false
A. Gas molecules are approximately the
same size as the distances between
them.
B. Gas molecules move randomly at
various speeds in all directions
C. Collisions between gas molecules are
elastic (that is, they bounce off of each
other)
a. C only
b. A and B
c. B and C
d. B only
e. A only
16. What is the total pressure of 2.00 g of H2
and 6.00 g of N2 in an 8.00 L container at
100 °C?
a. 1.24 atm
b. None of the other answers
c. 4.62 atm
d. 30.6 atm
e. 8.21 atm
Fill-in-the-blank (1 point per blank, no partial credit)
17. Which bond would you predict to be the
least polar?
a. N-N
b. C-N
c. B-N
d. N-H
e. O-N
NO2Write the Lewis structure
(include all resonance structures if any)
Draw the structure
(using wedges & dashed-wedges)
Write the electron-pair geometry (central atom)
Write the molecular geometry
Triangular planar
List all intermolecular forces (if any)
London forces & dipole-dipole
Bent
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
Some useful 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