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Dec 6, 2023
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Midterm Exam 3: General Chemistry I with Lab, Spring 2023
Thursday, April 20, 2023, Time allowed: 60 minutes
Instructions for the exam:
1. Write your Official name (as it appears on Canvas) and student ID on both the exam and the bubble
sheet.
2. Multiple-choice questions will be graded based on the answers on the bubble sheet, so be sure to
transfer all your answers accurately.
3. To receive full credit, show all your steps completely and clearly.
4. Use the provided solution boxes to do all your work.
Name:
Student ID:
Grade Table
: This exam consists of
19 questions
Page
Points
Score
2
20
3
16
4
20
5
8
6
12
7
16
8
8
Total:
100
Exam 3
Multiple choice questions
1.
One mole of
C
12
H
22
O
11
molecules contain:
[4 points]
A. 12 carbon atoms
B. 44 total atoms
C. 12 moles of carbon atoms
D. 6
.
023
∗
10
23
carbon atoms
2.
The percent water in the hydrate
CuSO
4
.
6
H
2
O
is:
[4 points]
A. 40.4%
B. 6.73%
C. 9.60%
D. 57.6%
3.
A combustion analysis of an unknown compound shows that it contains 74.0% carbon, 8.7% hydrogen,
and the rest is nitrogen. What is the empirical formula of this unknown compound?
[4 points]
A.
C
6
.
2
H
8
.
6
N
1
.
23
B.
C
10
H
14
N
2
C.
C
5
H
7
N
D.
C
6
H
9
N
4.
A sample of an unknown compound has an empirical formula of CoC
4
O
4
.
What is the molecular
formula of the compound if its molecular mass has been experimentally determined to be 341.86
g/mol?
[4 points]
A. CoC
4
O
4
B. Co
2
C
4
O
4
C. Co
2
C
8
O
8
D. Co
3
C
12
O
12
5.
What is the sum of the coefficients for the balanced chemical reaction that occurs when oxygen gas
and hydrogen sulfide gas react to form water and gaseous sulfur dioxide?
[4 points]
A. 9
B. 4
C. 15
D. 5
April, 20 2023
Page 2 of 12
Exam 3
6.
Calculate the volume of 18.0 M sulfuric acid that must be used to prepare 15.5 L of 0.195 M solution.
[4 points]
A. 92.3 mL
B. 168 mL
C. 0.338 L
D. 1.25 L
7.
Elon Musk’s SpaceX launches a new rocket and collects a rock sample from Mars. Scientists discover
that there is a fixed volume of unknown gas trapped inside the rock.
If 1.05 mL of the gas was
extracted from the rock at STP and determined to weigh 0.188 mg, what would be the identity of
the unknown gas?
[4 points]
A. Hydrogen
B. Nitrogen
C. Krypton
D. Helium
8.
A balloon filled with helium on a hot day (30
◦
C) has a volume of 37
.
8 mL. What volume will the
balloon occupy if the temperature drops to 25
◦
C?
[4 points]
A. 37
.
8 mL
×
(
298 K
303 K
)
B. 37
.
8 mL
×
(
303 K
298 K
)
C. 37
.
8 mL
×
(
30
◦
C
25
◦
C
)
D. 37
.
8 mL
×
(
25
◦
C
30
◦
C
)
(This text is for questions 9-11) A group of students measured the time it takes for different compounds
to diffuse across a room that was about 20 meters wide. They made the measurements on different
days and recorded the following data:
Day
Temperature
Time to other side (sample 1)
Time to other side (sample 2)
1
300K
52 sec
96 sec
9.
The molar mass ratio of sample 1 / sample 2 is:
[4 points]
A. 96
/
52
B. 52
/
96
C. (52
/
96)
2
D.
p
52
/
96
April, 20 2023
Page 3 of 12
Exam 3
10.
If the students measured the time of diffusion on a very cold day (273 K), the molar mass ratio of
sample 1 / sample 2 would
[4 points]
A. stays the same
B. decrease because the particles are moving slower
C. decrease because the lighter particles move faster
D. increase because the heavier particles move faster
11.
The best estimate of the time it would take sample 1 to diffuse to the other side of the room on the
cold day (T=273 K), is
[4 points]
A. 49 sec
B. 52 sec
C. 55 sec
D. 57 sec
12.
Nitrogen will behave most like an ideal gas
[4 points]
A. at high temperature and low pressure.
B. at low temperature and high pressure.
C. at intermediate (moderate) temperature and pressure.
D. at low temperature and low pressure.
E. at high temperature and high pressure.
13.
A solution of potassium hydroxide is mixed with chromium (III) nitrate.
The balanced net ionic
equation for the reaction occurring in the container is:
[4 points]
A. Cr
2+
(aq) + 2OH
−
(aq)
→
Cr(OH)
2
(s)
B. Cr
3+
(aq) + 3OH
−
(aq)
→
Cr(OH)
3
(s)
C. Cr(NO
3
)
3
(aq) + 3KOH (aq)
→
3KNO
3
(aq) + Cr(OH)
3
(s)
D. Cr
3+
(aq) + 3NO
−
3
(aq) + 3K
+
(aq) + 3OH
−
(aq)
→
3K
+
(aq) + 3NO
−
3
(aq) + Cr(OH)
3
(s)
14.
Which of the following is an oxidation-reduction reaction?
[4 points]
A. Cu (s) + 2AgNO
3
(aq)
→
2Ag (s) + Cu(NO
3
)
2
(aq)
B. HCl (aq) + NaOH (aq)
→
H
2
O (l) + NaCl (aq)
C. AgNO
3
(aq) + HCl (aq)
→
AgCl (s) + HNO
3
(aq)
D. Ba(C
2
H
3
O
2
)
2
(aq) + Na
2
SO
4
(aq)
→
BaSO
4
(s) + 2NaC
2
H
3
O
2
(aq)
E. H
2
CO
3
(aq) + Ca(NO
3
)
2
(aq)
→
2HNO
3
(aq) + CaCO
3
(s)
April, 20 2023
Page 4 of 12
Exam 3
15.
Select the best statement relating to the following reaction:
[4 points]
2 MnO
2
(s) + KClO
3
(aq) + 2 KOH(aq)
→
2 KMnO
4
(aq) + KCl(aq) + H
2
O(l)
A.
K
in
KClO
3
is the reducing agent.
B.
H
in
KOH
is oxidized.
C.
Cl
in
KClO
3
is the reducing agent.
D.
O
in
KClO
3
is the oxidizing agent.
E.
Mn
in
MnO
2
is oxidized.
16.
Based on the activity series, which one of the reactions below will occur?
[4 points]
A. Fe (s) + ZnCl
2
(aq)
→
FeCl
2
(aq) + Zn (s)
B. Mn (s) + NiCl
2
(aq)
→
MnCl
2
(aq) + Ni (s)
C. Pb (s) + NiI
2
(aq)
→
PbI
2
(aq) + Ni (s)
D. SnBr
2
(aq) + Cu (s)
→
CuBr
2
(aq) + Sn (s)
E. None of the reactions will occur.
April, 20 2023
Page 5 of 12
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Timed Test
Multiple Attempts Not allowed. This test can only be taken once.
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Remaining Time: 1 hour, 34 minutes, 00 seconds.
* Question Completion Status:
A Moving to the next question prevents changes to this answer.
Question 2
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