2/22/13
Assessment
Summer 2010 Test 1
Started:
February 22, 2013 8:07 AM
Submitted:
February 22, 2013 8:07 AM
Time spent:
00:00:04
Total score: 0/20 = 0%
Done
1.
Which type of intermolecular/interparticle force exists in all solid substances?
Student Value
Response
Correct Answer Feedback
A. Ionic
B. London
Dispersion
C. None there are
different
types of
IMF/IPF
depending
on the
substance
D. Dipoledipole
E. Hydrogen
bonding
Score:
0/1
2.
Which of the following substances would be expected to have the highest melting point?
Student
Response
Value
Correct
Answer
Feedback
A. CH3OCH3
B. CH3CH2CH2OH
C. CH3CH2OH
D. HOCH2CH2OH
E. CH3CH2CH2CH2CH3
Score:
0/1
3.
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Assessment
Rank the various "heats" of water in order of increasing size.
Student
Response
Value
Correct Answer Feedback
A. heat of
sublimation
< heat of
vaporization
< heat of
fusion
B. heat of
sublimation
< heat of
fusion <
heat of
vaporization
C. heat of
fusion =
heat of
sublimation
= heat of
vaporization
D. heat of
fusion <
heat of
vaporization
< heat of
sublimation
E. heat of
fusion <
heat of
sublimation
< heat of
vaporization
Score:
0/1
4.
How much energy in J is needed to convert 80 g of liquid ethanol at 70 oC to vapor at 101oC.
You might need to know that:
mp = -114 oC and bp = 78oC
The heat of fusion is 4.6 kJ/mol and the heat of vaporization is 46.0 kJ/mol.
Finally, the specific heats of the solid, liquid and gas are, respectively 2.1, 3.2 and 1.8 J/g
oC.
Student Value
Response
Correct Answer Feedback
A. 87200
B. 5360
C. 3,685,000
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D. 85400
E. 13400
Score:
0/1
5.
For a pure substance, three phases are present simultaneously at
Student Value
Response
Correct Answer Feedback
A. none of
these
B. the
critical
point
C. the normal
boiling
point
D. the triple
point
E. the normal
melting
point
Score:
0/1
6.
Which of the following statements is true?
Student
Response
Value
Correct Answer Feedback
A. A solution
can only
have one
volatile
component.
B. The
difference
between the
vapor
pressure of a
pure solvent
and the
vapor
pressure of a
solution is
proportional
to the
concentration
of the solute.
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Assessment
C. Water and
pentane form
a solution
when mixed.
D. Ideal
colligative
properties do
not depend
on the nature
of the solute
particles in a
given
solution.
E. The
solubilities of
solids in
liquids are
dependent of
the pressure
above the
solution.
Score:
0/1
7.
Which solvent will be better able to dissolve the given solute?
(I) HCl(g) in water or hexane(l)
(II) methane(g) in water or carbon tetrachloride(l)
(III) NaCl(s) in ethanol or in hexane
Student
Response
Value
Correct Answer Feedback
A. hexane,
carbon
tetrachloride,
hexane
B. water,
water,
ethanol
C. hexane,
water,
ethanol
D. water,
carbon
tetrachloride,
ethanol
E. water,
water,
hexane
Score:
0/1
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Assessment
8.
Calculate the molarity of an aqueous solution that is 15.6% by mass calcium chloride. You
might need to know that the density is 1.16 g/mL.
Student Value
Response
Correct Answer Feedback
A. 0.163
B. 1.63
C. 1.405
D. 2.40
E. 2.07
Score:
0/1
9.
If the freezing point constant for water is 1.86 ºC/m and assuming ideal conditions,
determine the freezing point of a 0.0100 m aqueous solution of Na2SO4.
Student Value
Response
Correct Answer Feedback
A. -0.0558
ºC
B. -0.0062
ºC
C. -0.0372
ºC
D. -0.0186
ºC
E. -0.0744
ºC
Score:
0/1
10.
A solution that is a mixture of 0.4 mol C2H4Br2 and 0.6 mol C3H6Br2 has a vapor pressure of
145 mmHg at a particular temperature. Determine the vapor pressure of pure C3H6Br2 at this
temperature, given that the vapor pressure of pure C2H4Br2 is 173 mmHg at this temperature
and that the solution obeys Raoult's law.
Student Value
Response
Correct Answer Feedback
A. 75.8
mmHg
B. 69.2
mmHg
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C. 126 mmHg
D. 28 mmHg
E. 117 mmHg
Score:
0/1
11.
3.21 grams of a protein that has a molar mass of 16,000 g/mol are dissolved in 25.0 mL of
water at 25 ºC. Calculate the osmotic pressure in mmHg.
Student Value
Response
Correct Answer Feedback
A. 19.9
B. 0.196
C. 3141
D. 0.149
E. 149
Score:
0/1
12.
A water-soluble compound has an empirical formula of CH2O. When 1.00 g of the compound
are dissolved in 50.0 g of water, the solution freezes at -0.62 ºC. Given that the freezing
point constant of water is 1.86 ºC/m, what is the molecular formula of the compound?
Student Value
Response
Correct Answer Feedback
A. CH2O
B. C2H4O2
C. C5H10O5
D. C3H6O3
E. C4H8O4
Score:
0/1
13.
For the reaction,
N2O4(g) → 2 NO2(g),
the number of moles of N2O4(g) present at certain times is,
Time = 0, moles N2O4(g) = 0.200
Time = 5 minutes, moles N2O4(g) = 0.170
Time = 10 minutes, moles N2O4(g) = 0.140
How many moles of NO2 are present after 10 minutes (assuming there were 0 at time = 0)?
Student
Value
Correct Answer Feedback
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Response
A. 0.120
moles
B. 0.140
moles
C. 0.060
moles
D. 0.110
moles
E. 0.280
moles
Score:
0/1
14.
The reaction between NO and I2 is first order in NO and second order in I2. What change in
rate will result when the initial concentrations of both are tripled?
Student Value
Response
Correct Answer Feedback
A. 81-fold
increase
B. 6-fold
increase
C. 27-fold
increase
D. 3-fold
increase
E. 18-fold
increase
Score:
0/1
15.
For the reaction, S2O82-(aq) + 2 I-(aq) => I2(aq) + 2 SO42-(aq), the following data were
obtained at constant temperature. The times listed are those taken to reach a measurable
amount of iodine.
Experiment
Initial [S2O82-], mol/L Initial [I-], mol/L
Time, sec
1
0.0400
0.0800
40
2
0.0400
0.0400
80
3
0.0100
0.0800
160
4
0.0200
0.0200
?
What is the expected time for experiment 4?
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Student Value
Response
Correct Answer Feedback
A. 320
B. 5
C. 160
D. 240
E. 80
Score:
0/1
16.
For the reaction, A → B, the rate constant is 0.0208 sec -1. How long would it take for [A] to
decrease from 0.100 to 0.0450 M?
Student Value
Response
Correct Answer Feedback
A. 16.7 sec
B. 588 sec
C. 107 sec
D. 38.4 sec
E. 0.0166
sec
Score:
0/1
17.
The first-order disappearance of a substance has a half-life of 34.0 s. How long does it take
for the concentration of the substance to fall to 12.5% of the original value?
Student Value
Response
Correct Answer Feedback
A. 4.25 s
B. 102 s
C. 68 s
D. 11 s
E. 272 s
Score:
0/1
18.
The rate law of a particular reaction is found to be, rate = k[A]2[B]. Which of the following
statements is FALSE?
Student
Response
Value
Correct Answer Feedback
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Assessment
A. Tripling the
concentration
of A will result
in a nine-fold
increase in the
rate
B. The units of k
could be
(L2/mol2 sec)
C. The reaction is
third order
overall.
D. The actual
value of k will
depend on the
concentrations
of A and B.
E. The actual
value of k will
depend on the
temperature
Score:
0/1
19.
The kinetics of the decomposition of dinitrogen pentoxide are studied at 50 ºC and 75 ºC.
Which of the following statements about these studies is correct?
Student
Response
Value
Correct Answer Feedback
A. The rate at
75 ºC will be
greater than
that at 50 ºC
because the
concentration
of a gas
increases
with
increasing
temperature
B. The rate at
75 ºC will be
lower than
that at 50 ºC
because the
molecules
with higher
speeds do
not interact
as well as the
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Assessment
ones at lower
speeds
C. The rate at
75 C will be
greater than
that at 50 ºC
because the
activation
energy is
lower at 75
ºC
D. The rate at
75 ºC will be
greater than
that at 50 ºC
because the
number of
molecules
with enough
energy to
react
increases
with
temperature
E. The rate at
75 ºC will be
greater than
that at 50 ºC
because the
activation
energy is
higher.
Score:
0/1
20.
A reaction has a rate constant of 1.23 x 10-2 s-1 at 20.0 °C and an activation energy of 52.0
kJ/mol. What is the rate constant at 40.0 °C?
Student Value
Response
Correct Answer Feedback
A. 4.81 x
10-2
B. 1.23 x
10-2
C. 9.02 x
10-3
D. 3.14 x
10-3
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E. 1.68 x
10-2
Score:
0/1
Done
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