Test 3 - Gauthier Joseph Exam 3 Due Nov 8 2007 11:00 pm...

Gauthier, Joseph – Exam 3 – Due: Nov 8 2007, 11:00 pm – Inst: Vandenbout 1
This print-out should have 30 questions.
Multiple-choice questions may continue on
the next column or page – find all choices
before answering. The due time is Central
time.
Vanden Bout 2 PM
ONLY ! ! ! !
001 (part 1 of 1) 10 points
Two gases are contained in gas bulbs con-
nected by a valve. Gas A is present in a 18 L
bulb at a pressure of 473 torr. Gas B exerts a
pressure of 651 torr in a 73 L bulb. What is
the partial pressure of gas B after they equili-
brate once the valve has been opened?
Correct answer: 522 torr.
Explanation:
V
A
= 18 L P
A
= 473 torr
V
B
= 73 L P
B
= 651 torr
V
total
= V
A
+ V
B
= 91 L
P
B
V
B
= P
t
V
t
P
t
=
P
B
V
B
V
t
=
(651 torr) (73 L)
91 L
= 522 torr
002 (part 1 of 1) 10 points
Which of the following is NOT a characteristic
of a hydrogen bond?
1. It is responsible for the unusual physical
properties of water.
2. It can occur when hydrogen is covalently
bound to very electronegative elements liks F,
Cl, Br and I. correct
3. It is stronger than other dipole-dipole
interactions.
4. It is weaker than a covalent bond.
Explanation:
Hydrogen bonding only ocurs when hydro-
gen is covalently bonded to very electronega-
tive elements like O, N or F.
003 (part 1 of 1) 10 points
The following experiment was carried out us-
ing a newly synthesized chlorofluorocarbon.
Exactly 50 mL of the gas effused through a
porous barrier in 157 s. The same volume of
argon effused in 76 s under the same condi-
tions. Which compound is the chlorofluoro-
carbon?
1. C
2
Cl
5
F
2. C
2
Cl
2
F
4
correct
3. C
2
ClF
5
4. C
2
Cl
3
F
3
5. C
2
Cl
4
F
2
Explanation:
004 (part 1 of 1) 10 points
Consider four molecules
I) CHCl
3
II) CH
4
III) CH
3
Cl
IV) CCl
4
Which of these exhibit permanent dipole-
dipole interactions?
1. I only
2. I and III only correct
3. None of these
4. III only
5. I, III, and IV only
Explanation:
Dipole-dipole interactions occur in polar
molecules. CHCl
3
and CH
3
Cl are polar be-
cause their dipole moments do not cancel.
CH
4
and CCl
4
are symmetric; their dipole
moments cancel and the overall molecule is
non-polar.
005 (part 1 of 1) 10 points

Gauthier, Joseph – Exam 3 – Due: Nov 8 2007, 11:00 pm – Inst: Vandenbout 2
Which best describes the hydrogen bonding
between two water molecules?
hydrogen
oxygen
1.
2. correct
3.
4.
Explanation:
Note the water molecules line up as the δ
-
on the O of one molecule is aligned with a δ
+
on a H of another molecule.
006 (part 1 of 1) 10 points
Under what conditions is a gas most likely to
deviate from ideal behavior?
1. low density
2. high pressure correct
3. when considering noble gases
4. high temperatures
Explanation:
Under high pressure, there are many more
collisions between molecules. This increases
the likelihood that a non-ideal interaction will
occur.
007 (part 1 of 1) 10 points
At room temperature which of the following
gases will have the fastest average velocity?