University of Saskatchewan
Department of Chemistry
CHEMISTRY 112.3
Midterm Examination
February 13, 2012 (6 PM – 8 PM)
VERSION M3
Last Name (please print clearly!)____________________________________________
Given Name (please print clearly!)_____________________________________________
Student Number
Signature___________________________________
Please indicate your section:
Section 01
Section 03
Section C15
MWF 9:30 AM
TR 10:00 AM
North West
Dr. A. Grosvenor
Dr. P. Ahiahonu
Dr. R. Catton
INSTRUCTIONS - PLEASE READ THIS FIRST!
1. This is a closed-book examination. A data-sheet with a Periodic Table is attached to the last page of this
examination paper (you can remove this page from the booklet for convenience)
2. Simple scientific calculators are permitted. Alphanumeric calculators and those capable of storing
equations are not permitted. Cell phones, personal digital assistants, electronic dictionaries, etc. are not
allowed. No equations may be stored in memory of electronic devices.
3. This examination paper has 10 pages, including the data sheet. To ensure that your copy is complete and to
become familiar with the questions, please read through the entire examination before you answer any
questions.
4. You can use the backside of the pages as scratch paper.
5. A total of 100 marks can be obtained. Each of the 40 questions will be weighted with 2.5 marks each.
6. Please fill out the top of this paper and the top of the blue op-scan sheet. Print your name and code
your student number in soft pencil.
7. Answer these questions by circling the response on this paper AND by filling out the corresponding
response on the blue opscan sheet USING A SOFT-LEAD PENCIL ONLY. No deductions will be made
for incorrect answers, but multiple answers will be treated as NO answer.
8. If you change your mind, erase the incorrect answer carefully from the blue optical scan sheet. In the
event of a discrepancy, the response on the opscan sheet will count.
9. HAND-IN ALL of your material (question sheet and computer sheet)
1. The acceleration due to gravity at a certain location is 32.2 ft/s2, what is its numerical value if it is expressed
in terms of m/h2? (1 ft (foot) = 30.48 cm; s = second; h = hour)
A. 3.53 × 104 m/h2
B. 1.27 × 108 m/h2
C. 4.17 × 108 m/h2
D. 3.95 × 109 m/h2
E. 8.56 × 10 m/h2
2. How many significant figures should be shown for the result of the following mathematical operation?
A. 3
B. 4
C. 1
D. 2
E. 5
3. An acetaminophen suspension for infants contains 80 mg of acetaminophen per 1.0 mL of liquid
(80 mg/1.0 mL). The recommended dose is 15 mg/kg body weight. How many mL of this suspension should
be given to an infant weighing 6.35 kg?
A. 1.0 mL
B. 0.19 mL
C. 1.191 mL
D. 1.2 mL
E. 0.76 mL
4. In 2009, the Greater Toronto area air had carbon monoxide (CO) levels of 12.0 L of CO per 1.00 x 106 L of
air. An average human inhales about 0.450 L of air per breath and takes about 25 breaths per minute. How
many milligrams of carbon monoxide does the average person inhale in a 12 hour period? Assume that
carbon monoxide has a density of 1.20 g/L.
A. 120 mg
B. 117 mg
C. 116.5 mg
D. 110 mg
E. 11.7 mg
5. A uniform sphere has a radius (R) of 18.0 mm and a density of 2.041 g/cm3, what is the value of its mass in
grams?
Given: volume of a sphere =
R3
A. 49.86 g
B. 50 g
C. 49.860 g
D. 49 g
E. 49.9 g
2
6. How many protons (p), electrons (e), and neutrons (n) are there in
?
A. 13 p, 10e, and 14 n
B. 27 p, 13e, and 27 n
C. 13p, 13e, and 14n
D. 13p, 14e, and 13 n
E. 13p, 13e, and 13n
7. During an experiment, a mixture of two organic liquids (having different boiling points) was separated using
a distillation apparatus. The solution was heated by burning natural gas in a Bunsen burner and resulted in
the component with the lowest boiling point evaporating first. The flame of the burner was kept too close to
the bottom of the flask and some of the organic mixture decomposed into a black carbon deposit on the
inside of the flask. Identify the changes involved during this distillation as being chemical or physical.
A. Evaporation = chemical; Decomposition = chemical; Burning of natural gas =chemical
B. Evaporation = physical; Decomposition = physical; Burning of natural gas = chemical
C. Evaporation = physical; Decomposition = chemical; Burning of natural gas = chemical
D. Evaporation = physical; Decomposition = physical; Burning of natural gas = physical
E. Evaporation = chemical; Decomposition = physical; Burning of natural gas = physical
8. What is the mass number of an iron atom that has 28 neutrons?
A.
B.
C.
D.
E.
26
28
45
53
54
9. The density of water is 1.00 g/mL at 4oC. How many water molecules are present in 2.56 mL of water at this
temperature?
A. 8.56 × 1021
B. 6.022 × 1020
C. 6.022 × 1023
D. 8.56 × 1022
E. 2.011 × 1023
10. The “lead” in lead pencils is actually almost pure carbon, and the mass of a period mark made by a lead
pencil is about 0.0001g. How many carbon atoms are in the period?
A. 6 × 1021 atoms
B. 6.022 × 1023 atoms
C. 5 × 1018 atoms
D. 5 × 1022 atoms
E. 3.011 × 1023 atoms
3
11. The fictional isotope Xium-60 has an atomic mass of 60.15 units while Xium-70 has an atomic mass of
70.16 units. The average mass of Xium is 69.41 units. What is the fractional abundance of Xium-70?
Assume that only these two isotopes of Xium occur in nature.
A. 9.25
B. 1.95
C. 0.875
D. 0.925
E. 0.0925
12. Which of the following is the definition of the value of Avogadro’s constant.
A. The number of carbon atoms in exactly 1 g of carbon-12
B. The number of hydrogen atoms in exactly 1 g of hydrogen-1
C. The number of hydrogen atoms in exactly 12 g of hydrogen-1
D. The number of carbon atoms in exactly 12 g of carbon-12
E. None of the above
13. Choose the incorrect statement:
A. An anion is a positive ion
B. A molecule is a group of atoms bonded together that exists as an entity
C. Ionic compounds result from combinations of metals and non-metals.
D. The empirical formula is the simplest formula of the ratio of atoms.
E. The molecular formula is the listing of the atoms in an actual molecule.
14. Which of the following elements would have chemical properties that are most similar to those of Gallium?
A. Gadolinium
B. Germanium
C. Zinc
D. Aluminum
E. All must have the same properties because all these elements are metals
15. How many hydrogen atoms are there in 12.4 g of Al2(HPO4)3?
A. 4.39 x 1022
B. 6.55 x 1022
C. 6.07 x 1022
D. 1.09 x 1022
E. 1.32 x 1023
16. Which of the following species contains the greatest number of S atoms?
A. 30 mL of CS2 (density = 1.2 g/mL)
B. 0.14 mol S8
C. 0.30 mol SO2
D. 45 g S2O
E. They all contain the same number of S atoms
4
17. A compound is found to have the following percent mass composition: 38.7% K,
13.8% N, 47.5% O. What is the empirical formula of the compound?
A. K 2NO3
B. KNO 2
C. KNO 3
D. K 2N 2O3
E. K 2NO 2
18. Choose the incorrect chemical formula and name combination.
A. SiO2; silicon dioxide
B. Cu3(PO4)2; copper(II) phosphate
C. HClO; hypochlorous acid
D. CaH2; calcium hydroxide
E. AlCl3; aluminum chloride
19.The complete combustion of a sample of a pure organic compound containing C and H yielded 0.973 g of
CO2 and 0.299 g of H2O. The empirical formula of this compound is:
A.
B.
C.
D.
E.
C2H 3
C3H5
C4H6
C5 H8
C6H9
20. The name of which compound ends in “ate”?
A. HNO3
B. Na2CrO4
C. Na2S
D. Na ClO2
E. H2SO3
21. The molecular formula for a sugar molecule is C12H22O11 . What is the mass percent of C in the molecule?
A. 42.12 %
B. 67.88 %
C. 2.37 %
D. 26.67 %
E. 8.34 %
5
22. What is the sum of all stoichiometric coefficients when the following chemical equation is balanced?
H2SO3(aq) + Al(OH) 3(aq)  Al2(SO3)3(aq) + H2O(l)
A. 4
B. 5
C. 12
D. 14
E. 11
23. For the following reaction, calculate the mass of carbon dioxide (CO2(g)) produced from the combustion of
44.0 g of CH4(g).
CH4(g) + 2O2(g)  CO2(g) + 2H2O(g) (Note: assume that O2(g) is present in excess.)
A.
B.
C.
D.
E.
118 g
60.4 g
87.8 g
121 g
44.0 g
24. Balance the following chemical equation and identify the correct stoichiometric coefficients.
a C3H6(l) + b O2(g) → c CO2(g) + d H2O(g)
A.
B.
C.
D.
E.
a=
a=
a=
a=
a=
2; b =
1; b =
1; b =
3; b =
4; b =
9; c = 6; d = 6
2; c = 2; d = 1
4.5; c = 3; d = 3
12; c = 12; d = 8
18; c = 12; d = 12
25. For the combustion reaction of CH4(g), determine which molecule represents the limiting reagent if 4.0 mols
of CH4(g) reacts with 5.5 mols of O2(g) to form 2.75 mols of CO2(g).
A.
B.
C.
D.
E.
All reagents are present in the proper proportions (i.e., none are limiting)
CH4
CO2
O2
H2 O
26. For the following reaction, calculate the number of mols of SrCl2(aq) that would be required to form 40.0 g
of Sr3(PO4)2(s).
3SrCl2(aq) + 2Li3PO4(aq)  Sr3(PO4)2(s) + 6LiCl(aq)
A.
B.
C.
D.
E.
0.0883 mols
0.530 mols
0.132 mols
0.265 mols
0.0945 mols
6
27. Balance the skeletal equation presented below and identify the reducing agent and the oxidizing agent.
Ca(s) + H2O(l)  Ca(OH)2(aq) + H2(g)
A. Ca(s) + H2O(l)Ca(OH)2(aq) + H2(g); reducing agent = Ca(OH)2; oxidizing agent = H2O
B. Ca(s) + 2H2O(l)  Ca(OH)2(aq) + H2(g); reducing agent = Ca; oxidizing agent = H2O
C. Ca(s) + H2O(l)  Ca(OH)2(aq) + H2(g); reducing agent = Ca; oxidizing agent = H2O
D. Ca(s) + H2O(l)  Ca(OH)2(aq) + H2(g); reducing agent = Ca; oxidizing agent = Ca(OH)2
E. Ca(s) + 2H2O(l)  Ca(OH)2(aq) + H2(g); reducing agent = H2O; oxidizing agent = Ca
28. Calculate the total volume of a solution if 300 mL of 0.25 mol/L NaOH is diluted to have a final
concentration of 0.10 mol/L.
A.
B.
C.
D.
E.
30 mL
75 mL
750 mL
2500 mL
120 mL
29. Calculate the theoretical yield and percent yield if the reaction of 50.0 g of Fe and 27.0 g of O2(g) was found
to produce 69.5 g of Fe2O3(s).
4Fe(s) + 3O2(g)  2Fe2O3(s)
A.
B.
C.
D.
E.
Theoretical yield = 89.8; Percent yield = 77.4 %
Theoretical yield = 89.8 g; Percent yield = 89.3 %
Theoretical yield = 71.5 g; Percent yield = 77.4 %
Theoretical yield = 69.5 g; Percent yield = 100 %
Theoretical yield = 71.5 g; Percent yield = 97.2 %
30. What volume of 0.0450 mol/L HClO4(aq) is needed to titrate 30.0 mL of a 0.250 mol/L solution of
NaOH(aq)?
A. 167 mL
B. 5.40 mL
C. 7.50 mL
D. 33.0 mL
E. 100 mL
31. Of the following three reactions, which is a REDOX reaction?
(1) Al2O3(s) + Ga2O3(s)  2AlGaO3(s)
(2) CrBr2(aq) + Na2CO3(aq)  CrCO3(s) + 2NaBr(aq)
(3) 4FeO(s) + 4SrCO3(s) + O2(g)  2Sr2Fe2O5(s) + 4CO2(g)
A.
B.
C.
D.
E.
All of the above
None of the above
(1)
(2)
(3)
7
32. In the following balanced REDOX reaction, what element is oxidized?
Au2O3(s) + 3H2(g)  2Au(s) + 3H2O(l)
A.
B.
C.
D.
E.
All of the above
None of the above
Au
O
H
33. What mass of CaCl2 is present in a 6.2 L solution having a concentration of 0.450 mol/L?
A.
B.
C.
D.
E.
40 g
310 g
112 g
688 g
50 g
34. Of the following 1 mol/L aqueous solutions, how many are likely to conduct electricity:
H2SO4, C6H12O6, HC2H3O2, NaCl?
A. 3
B. 1
C. 4
D. 2
E. All of the above
35. Determine the percent yield of Rb(s) formed by the following (unbalanced) reaction, if 200 Kg of RbCl(l)
was reacted with 50 Kg of Ca(s) to produce 99 Kg of Rb(s).
RbCl(l) + Ca(s)  CaCl2(s) + Rb(s)
A. 30 %
B. 45 %
C. 70 %
D. 93 %
E. 215 %
36. Write the balanced ionic equation for the reaction of Na2CO3 and LiCl to form Li2CO3 and NaCl.
A. 2Na+(aq) + CO32-(aq) + 2Li+(aq) + 2Cl-(aq)  2Li+(aq) + CO32-(aq) + 2Na+(aq) + 2Cl-(aq)
B. Na2CO3(s) + 2LiCl(aq)  Li2CO3(s) + 2Na+(aq) + 2Cl-(aq)
C. 2Na+(aq) + CO32-(aq) + 2LiCl(s)  2Li+(aq) + CO32-(aq) + 2Na+(aq) + 2Cl-(aq)
D. Na2CO3(aq) + 2LiCl(aq)  Li2CO3(aq) + 2NaCl(aq)
E. None of the above
8
37. In the following balanced reaction, which material represents the precipitate?
Ag2NO3 + Na2SO4  Ag2SO4 + Na2NO3
A. No precipitate forms.
B. Ag2NO3
C. Na2SO4
D. Ag2SO4
E. Na2NO3
38. What is the balanced (molecular) chemical equation for the gas-evolving reaction of Na2SO3(aq) and
HCl(aq).
A. Na2SO3(aq) + 2HCl(aq)  2NaCl(aq) + H2O(l) + SO2(g)
B. Na2SO3(aq) + 2HCl(aq)  2NaCl(aq) + H2SO3(aq)
C. SO32-(aq) + H+(aq)  H2O(l) + SO3(g)
D. Na2SO3(aq) + HCl(aq)  3NaCl(aq) + 2H2O(l) + SO2(g)
E. None of the above
39. Determine the oxidation state of the transition-metal in FePO4 and give the proper name for this ionic
compound.
A. Oxidation state = 0 ; Name = Iron phosphate
B. Oxidation state = 3+ ; Name = Iron (III) phosphate
C. Oxidation state = 2+ ; Name = Iron (II) phosphate
D. Oxidation state = 3- ; Name = Iron (III) phosphate
E. Oxidation state = 4+ ; Name = Iron (IV) phosphate
40. Which of the following descriptions cannot be used to describe electrolyte solutions:
A. May contain acids
B. Contains water
C. Does not conduct electricity
D. Contains ions
E. All of the above
9
1
1A
1
1.00794
2
2A
3
4
H
18
8A
Periodic Table of the Elements
13 14
3A 4A
5
6
15
5A
16
6A
7
8
2
17
He
7A 4.00260
9
10
Li
Be
B
C
N
O
F
Ne
6.941
9.01218
10.811
12.011
14.0067
15.9994
18.9984
20.1797
11
12
13
14
15
16
17
18
3
4
5
Na Mg
3B 4B 5B
22.9898
24.3050
22
8
8B
9
8B
10
8B
11
1B
12
2B
Al
Si
P
S
26.9815
28.0855
30.9738
32.066
35.4527
39.948
24
25
26
27
28
29
30
31
32
33
34
35
36
Cr Mn Fe
Co
Ni
Cu Zn Ga Ge As
Se
Br Kr
Cl Ar
20
K
Ca
39.0983
40.078
44.9559
47.88
50.9415
51.9961
54.9381
55.847
58.9332
58.693
63.546
65.39
69.723
72.61
74.9216
78.96
79.904
83.80
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
Sc Ti
Y
23
7
7B
19
Rb Sr
21
6
6B
V
Zr Nb Mo Tc
Ru Rh
Pd
Ag Cd In
Sn
Sb
Te
I
Xe
85.4678
87.62
88.9059
91.224
92.9064
95.94
(98)
101.07
102.906
106.42
107.868
112.411
114.818
118.710
121.757
127.60
129.904
131.29
55
56
57
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
Bi
Po
208.980
(209)
Cs Ba La Hf Ta
W
Re
Os
Ir
Pt
Au Hg Tl Pb
132.905
137.327
138.906
178.49
180.948
183.84
186.207
190.23
192.22
195.08
196.967
200.59
87
88
89
104
105
106
107
108
109
110
111
112
114
116
118
(287)
(289)
(293)
Fr Ra Ac Rf Db Sg
(223)
226.025
227.028
(261)
Bh
204.383
207.2
At Rn
(210)
(222)
Hs Mt
(262)
(263)
(262)
(265)
(266)
(269)
(272)
(272)
58
59
60
61
62
63
64
65
66
67
68
69
70
71
Ce
Pr
Nd Pm Sm Eu
Gd Tb Dy Ho Er Tm Yb Lu
140.115
140.908
144.24
(145)
150.36
151.965
157.25
158.925
162.50
164.930
167.26
168.934
173.04
174.967
90
91
92
93
94
95
96
97
98
99
100
101
102
103
Th Pa
232.038
231.036
U
238.029
Physical Constants
Constant
Atomic mass unit
Avogadro number
Gas Constant
Np Pu Am Cm Bk Cf Es Fm Md No Lr
237.048
(244)
Symbol
u
NA
R
(243)
(247)
(251)
Value
1.6605 × 10-27 kg
6.022 × 1023 mol-1
0.082058 L atm mol-1K-1
8.3145 J K-1 mol-1
62.364 L mmHg mol-1 K-1
22.414 L mol-1
9.109 × 10-31 Kg
Molar volume of an ideal gas at STP
Electron mass
Vm
me
Some SI Derived Units
Physical Quantity
Force
Energy
Pressure
Symbol
N
J
Pa
Unit
Newton
Joule
Pascal
(247)
Definition
kg m s-2
kg m2 s-2
N m-2 = kg m-1 s-2
STP Conditions: P = 1 atm = 760 Torr = 760 mmHg = 101.325 kPa
Temperature = 0 ºC = 273.2 K
10
(252)
(257)
(258)
(259)
(260)