AVOGADRO EXAM 2005
UNIVERSITY OF WATERLOO
DEPARTMENT OF CHEMISTRY
19 MAY 2005
TIME: 75 MINUTES
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AVOGADRO EXAM 2005 - Answers
1
How many significant digits are there in the quantity
6.2040×10−4 g?
A
three
B
four
5
*C five
2
D
six
E
eight
What is the name of the element that has the atomic
symbol S?
A
sodium
B
silicon
C
selenium
6
3
strontium
How many protons, electrons and neutrons are there
in an atom of 42Ca?
A
42 protons, 42 electrons and 42 neutrons
B
22 protons, 22 electrons and 20 neutrons
C
20 protons, 22 electrons and 22 neutrons
D
20 protons, 20 electrons and 42 neutrons
A
N
B
N
C
N
*D
N
E
N
Which of the following atoms has the largest first
ionization energy?
*A S
*D sulfur
E
What is the correct Lewis symbol for the nitrogen
atom?
7
B
Al
C
K
D
Mg
E
Sr
Which elements have the following characteristics?
•
•
•
*E 20 protons, 20 electrons and 22 neutrons
•
4
What is the ion most commonly formed by Al?
A
Al+
*B Al3+
C
soft, silver-coloured metals at 25oC and 101 kPa
react with halogens to form salts
react violently with water to form basic solutions
and liberate hydrogen gas
must be stored under oil or in a vacuum to
prevent reaction with oxygen
*A alkali metals
B
alkaline earth metals
C
transition metals
D
lanthanides
E
actinides
5+
Al
5−
D
Al
E
Al3−
 2005 UNIVERSITY OF WATERLOO AVOGADRO EXAM /2
8
Which of the following processes releases the most
energy per mole of ion produced?
soluble in water?
-
A
Na(g) + e → Na (g)
B
Na(g) → Na+(g) + e
C
Cl(g) → Cl+(g) + e
-
C
CH4
*D Cl(g) + e → Cl (g)
-
D
CaCO3
E
CO2
E
9
-
11 Which of the following compounds would be most
A
-
-
*B CH3OH
-
-
S(g) + e → S (g)
What is the chemical formula for chromium (III) oxide?
A
CrO
B
Cr3O
C
CrO3
D
Cr3O2
*E Cr2O3
CH3CH2CH2OH
12 Which of the following compounds exhibits the
strongest hydrogen bonding amongst its molecules?
A
CH3Cl
B
H2C=CH2
C
H3C-O-CH3
*D NH3
E
CH3CH3
10 Which of the following bonds is polar covalent?
A
F-F
*B C-O
C
Na-Cl
D
Mg-O
E
Li-F
13 Which of the following compounds would have the
highest boiling point?
*A CH3CH2OH
B
CH3OH
C
CH4
D
H2C=CH2
E
HC≡CH
 2005 UNIVERSITY OF WATERLOO AVOGADRO EXAM /3
14 How many isomers of C3H4 are there?
17 Which process does not involve a chemical change?
A
one
A
an iron nail rusting
B
two
B
the burning of a candle
*C three
*C sugar dissolving in hot tea
D
four
D
souring of milk
E
more than four
E
explosion of gun powder
15 Which of the following structures are not valid Lewis
structures for the thiocyanate ion, SCN−?
S
C
N
S
(1)
C
S
N
C
N
N
(3)
(2)
S
C
S
(4)
C
18 What products are obtained when Zn(s) is added to a
dilute aqueous solution of hydrochloric acid, HCl(aq)?
A
Zn(OH)2(s) and H2(g)
B
ZnH2(aq) and Cl2(g)
*C ZnCl2(aq) and H2(g)
N
(5)
D
Zn(OH)2(s) and Cl2(g)
E
ZnO(s), H2(g) and Cl2(g)
19 What is the balanced chemical equation for the
A
(2), (3) and (4)
complete combustion of C3H8O in O2?
B
(1) and (4)
A
C3H8O + 5 O2 → 3 CO2 + 4 H2O
C
(3) and (4)
B
C3H8O + 7 O2 → 3 CO2 + 4 H2O
D
(1), (4) and (5)
C
2 C3H8O + 3 O2 → 6 CO2 + 8 H2O
D
2 C3H8O + 7 O2 → 6 CO2 + 8 H2O
*E (1) and (5)
*E 2 C3H8O + 9 O2 → 6 CO2 + 8 H2O
16 Which of the following solutions has no effect on both
blue and red litmus paper and is an excellent
20 What is the missing product in the reaction below?
conductor of electricity?
*A 1.0 mol L−1 KCl(aq)
−1
226
88 Ra
A
222
86 Ra
B
1.0 mol L
HCl(aq)
C
1.0 mol L−1 CH3CH2OH(aq)
*B
222
86 Rn
D
1.0 mol L−1 H2O2(aq)
C
230
90Th
E
1.0 mol L−1 NaOH(aq)
D
222
90Th
E
230
86 Rn
→
?
+
4
2 He
 2005 UNIVERSITY OF WATERLOO AVOGADRO EXAM /4
21 What is the coefficient of Cr(s) when the equation
24 When 1.72 g sample of impure magnesium chloride,
below is balanced using the smallest whole number
MgCl2, was treated with excess AgNO3(aq), 4.52 g of
coefficients?
dry AgCl(s) was obtained. What was the mass
Fe2+(aq) + Cr(s)
A
→
percentage of MgCl2 in the original sample?
Fe(s) + Cr3+(aq)?
1
*B 2
C
3
D
4
E
6
A
38.1%
B
57.3%
C
61.9%
Molar masses (in g mol-1):
MgCl2, 95.21 AgCl, 143.35
*D 87.3%
E
25 What is the concentration of a potassium hydrogen
22 What is the mass of a single C60 molecule?
−21
*A 1.20×10
phthalate (KHP) solution that was made by dissolving
3.823 g of KHP in a 250.0 mL volumetric flask?
g
B
4.34×10−26 g
C
1.66×10−24 g
D
8.36×10−20 g
E
9.96×10−23 g
94.7%
23 The balanced chemical equation for the reaction of
N2H4 with N2O4 is given below.
A
7.488×10-5 mol L−1
B
4.896×10-3 mol L−1
C
0.01872 mol L−1
D
0.01959 mol L−1
The molar mass of
KHP is 204.23 g mol-1.
*E 0.07488 mol L−1
2 N2H4(l) + N2O4(l) → 3 N2(g) + 4 H2O(g)
What is the maximum mass of N2 that can be
26 Vanillin is a flavouring agent that has the following
obtained from 0.100 kg N2H4 and 0.200 kg of N2O4?
Molar masses (in g mol-1):
N2, 28.02
N2H4, 32.052
*A 0.131 kg
B
0.0874 kg
C
0.0304 kg
D
0.150 kg
E
0.182 kg
composition by mass:
63.2% C
N2O4, 92.02
5.30% H
31.5% O
What is the empirical formula of vanillin?
A
C5H5O2
*B C8H8O3
C
C3H3O
D
C2H2O
E
C6H5O3
 2005 UNIVERSITY OF WATERLOO AVOGADRO EXAM /5
27 Nitric acid, HNO3, can be manufactured from
30 For dilute aqueous solutions, one part per million
ammonia, NH3, utilizing the three reactions shown
below. What is the maximum number of moles of
HNO3 that can be obtained from 4.00 moles of NH3?
(The NO produced in step 3 is not recycled back into
(ppm) is approximately equal to
A
1gL
C
1 µg L−1
A
1.33 mol
B
2.00 mol
The density of water
is 1 g mL−1.
*D 1 mg L−1
Step 2: 2 NO(g) + O2(g) → 2 NO2(g)
Step 3: 3 NO2(g) + H2O(l) → 2 HNO3(aq) + NO(g)
−1
B
step 2.)
Step 1: 4 NH3(g) + 5 O2(g) → 4 NO(g) + 6 H2O(l)
1 µmol L−1
E
1 µmol mL−1
31 For the reaction H2S + CH3− U CH4 + HS−,
methane, CH4, is
*C 2.67 mol
A
the conjugate base of CH3−
D
4.00 mol
*B the conjugate acid of CH3−
E
6.00 mol
C
the conjugate acid of HS−
D
the conjugate base of HS−
E
the conjugate base of H2S
28 What is the hydrogen ion concentration in natural
rainwater if the pH is 5.60 at 298 K?
A
B
-
5.6 mol L 1
32 Benzoic acid (C6H5CO2H) and phenol (C6H5OH) are
-1
organic acids. Use the data below to decide which
0.75 mol L
one of the following statements is false?
-
*C 2.5 × 10−6 mol L 1
Solution
pH at 298 K
−1
1.0 mol L C6H5CO2H(aq)
2.09
5.00
1.0 mol L−1 C6H5OH(aq)
-
D
3.7 × 10−3 mol L 1
E
4.0 ×105 mol L 1
-
29 What volume of 17.8 mol L−1 H2SO4(aq) solution is
required to make 1.50 L of 0.100 mol L−1 H2SO4(aq)?
A
2.67 mL
*B 8.43 mL
C
11.9 mL
D
119 mL
E
267 mL
A
Phenol is a weak acid.
B
Benzoic acid is a weak acid.
C
Less than 1% of phenol molecules are
dissociated in 1.0 mol L−1 C6H5OH(aq).
D
Benzoic acid is a stronger acid than phenol.
*E The conjugate base of benzoic acid is a stronger
base than the conjugate base of phenol.
 2005 UNIVERSITY OF WATERLOO AVOGADRO EXAM /6
36 The density of an unknown gas is 0.713 g L−1 at
33 Which of the following is the strongest acid?
0.00oC and 101 kPa. What is the molar mass of the
A
B
C
gas?
CH4
CH3OH
H
H
O
C
C
0.0446 g mol-1
B
0.0625 g mol-1
*C 16.0 g mol-1
O
H
H
D
A
D
22.4 g mol-1
E
31.4 g mol-1
H-C≡N
37 Nitrogen gas (N2) is collected over water at 303 K
*E
Cl
H
O
C
C
using the apparatus shown below. The total pressure
of the gas collected is 21 kPa, and the volume is
O
H
1.0 L. What is the mass of N2 in the sample collected?
H
N2(g)
The vapour pressure
of water is 4.2 kPa at
303 K.
o
34 A sample of gas occupies a volume of 3.00 L at 21 C
and 101 kPa. What volume does the gas occupy at
water
35oC and 91 kPa?
*A 3.49 L
A
240 mg
B
5.50 L
*B 190 mg
C
3.18 L
C
290 mg
D
2.83 L
D
8.6 mg
E
4.50 L
E
120 mg
35 What is the net ionic equation for the reaction
between Pb(NO3)2(aq) and KI(aq)?
A
Pb+(aq) + I−(aq) → PbI(s)
B
K+(aq) + NO3 (aq) → KNO3(s)
−
*C Pb2+(aq) + 2 I−(aq) → PbI2(s)
D
Pb2+(aq) + 2 I−(aq) → Pb(s) + I2(s)
E
K+(aq) + NO3 (aq) → K(s) + NO(g) + O2(g)
−
 2005 UNIVERSITY OF WATERLOO AVOGADRO EXAM /7
38 What volume of which reactant remains if 12.0 L of
40 A pure solid was heated at a constant rate until it was
CO(g) and 25.0 L of H2(g) react according to the
completely converted into gas. The temperature-time
chemical equation given below? Assume that the
graph for the heating process is shown below.
o
volumes of both gases are measured at 719 C and
F
151 kPa.
D
3 CO(g) + 7 H2(g) → C3H8(g) + 3 H2O(g)
A
Temp
13.0 L H2 remains
B
3.0 L H2 remains
C
1.3 L H2 remains
time
To what does the line segment CD correspond?
3.0 L CO remains
39 What quantity of heat is required to warm 125 L of
o
C
A
*D 1.3 L CO remains
E
B
E
A
solid being warmed
B
solid changing to liquid
*C liquid being warmed
o
water from 25 C to 75 C?
The density of water is 1.0 g mL−1. The specific
heat capacity of water is 4.18 J g−1 (oC)−1.
D
liquid changing into gas
E
gas being warmed
*A 2.6×107 J
B
6.3×106 J
C
2.1×103 J
D
1.5×106 J
E
3.9×107 J
 2005 UNIVERSITY OF WATERLOO AVOGADRO EXAM /8
DATA SHEET
AVOGADRO EXAM 2005
DETACH CAREFULLY
1
1A
1
H
1.008
3
Li
6.941
11
Na
22.99
19
K
39.10
37
Rb
85.47
55
Cs
132.9
87
Fr
(223)
2
2A
4
Be
9.012
12
Mg
3
24.31
3B
20
21
Ca
Sc
40.08 44.96
38
39
Sr
Y
87.62 88.91
56
57
Ba
La
137.3 138.9
89
88
Ac
Ra
226 227.0
4
5
4B
5B
22
23
Ti
V
47.88 50.94
40
41
Zr
Nb
91.22 92.91
72
73
Hf
Ta
178.5 180.9
104
105
Rf
Db
58
Ce
140.1
90
Th
232.0
59
Pr
140.9
91
Pa
231.0
6
6B
24
Cr
52.00
42
Mo
95.94
74
W
183.9
106
Sg
60
Nd
144.2
92
U
238.0
7
7B
25
Mn
54.94
43
Tc
(98)
75
Re
186.2
107
Bh
61
Pm
(145)
93
Np
237.0
8
←
26
Fe
55.85
44
Ru
101.1
76
Os
190.2
108
Hs
9
8B
27
Co
58.93
45
Rh
102.9
77
Ir
192.2
109
Mt
10
→
28
Ni
58.69
46
Pd
106.4
78
Pt
195.1
110
Uun
62
63
64
Sm
Eu
Gd
150.4 152.00 157.3
94
95
96
Pu
Am
Cm
(244) (243) (247)
11
1B
29
Cu
63.55
47
Ag
107.9
79
Au
197.0
111
Uuu
65
Tb
158.9
97
Bk
(247)
12
2B
30
Zn
65.38
48
Cd
112.4
80
Hg
200.6
112
Uub
66
Dy
162.5
98
Cf
(251)
13
3A
5
B
10.81
13
Al
26.98
31
Ga
69.72
49
In
114.8
81
Tl
204.4
113
Uut
67
Ho
164.9
99
Es
(252)
Constants:
Conversion factors:
NA = 6.022 × 1023 mol−1
1 atm = 101.325 kPa = 760 torr
R
=
0.082058 atm L K−1 mol−1
−1
=
8.3145 kPa L K mol
=
8.3145 J K−1 mol−1
Kw =
14
4A
6
C
12.01
14
Si
28.09
32
Ge
72.59
50
Sn
118.7
82
Pb
207.2
68
Er
167.3
100
Fm
(257)
15
5A
7
N
14.01
15
P
30.97
33
As
74.92
51
Sb
121.8
83
Bi
209.0
69
Tm
168.9
101
Md
(258)
16
6A
8
O
16.00
16
S
32.07
34
Se
78.96
52
Te
127.6
84
Po
(209)
70
Yb
173.0
102
No
(259)
17
7A
9
F
19.00
17
Cl
35.45
35
Br
79.90
53
I
126.9
85
At
(210)
18
8A
2
He
4.003
10
Ne
20.18
18
Ar
39.95
36
Kr
83.80
54
Xe
131.3
86
Rn
(222)
71
Lu
175.0
103
Lr
(260)
= 760 mm Hg
o
0 C = 273.15 K
−1
1.0×10−14 (at 298 K)
Ideal Gas equation:
PV = nRT
 2005 UNIVERSITY OF WATERLOO AVOGADRO EXAM /9