Download avogadro exam 2012 - University of Waterloo

AVOGADRO EXAM 2012
UNIVERSITY OF WATERLOO
DEPARTMENT OF CHEMISTRY
17 MAY 2012
TIME: 75 MINUTES
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AVOGADRO EXAM 2012 - Answers
1 How many protons are there in a single
A
35 2 −
16 S
ion?
5
14
What volume does 3.20 grams of methane gas,
o
CH4(g), occupy at 0 C and 101.325 kPa? Choose
the closest answer.
*B 16
C
18
D
19
E
33
A
1.12 L
B
2.24 L
C
3.40 L
*D 4.48 L
E
2
22.4 L
+
The combination of hydronium (H3O ) ions and
−
hydroxide (OH ) ions to form water molecules
is called
A
B
6
Which of the following substances has a normal
o
boiling point higher than 500 C?
precipitation
A
propane, C3H8
B
bromine, Br2
C
mercury, Hg
electrolysis
*C neutralization
D
hydrogenation
E
hydrolysis
*D sodium chloride, NaCl
E
3
4
Which of the following occurs when Na2O is added
to water?
7
sulfuric acid, H2SO4
−1
Elemental gold, Au(s), has a density of 19.3 g mL at
25°C. What is the volume of 42.5 grams of Au(s)?
A
The water freezes.
A
B
A gas is released.
*B 2.20 mL
C
A black precipitate is formed.
C
23.2 mL
*D Heat is liberated.
D
61.8 mL
E
E
820 mL
A white precipitate is formed.
Isotopes differ in
A
8
atomic number
*B number of neutrons
C
number of electrons
D
number of protons
E
nuclear charge
2 / AVOGADRO EXAM © 2012 UNIVERSITY OF WATERLOO
0.454 mL
o
At 25 C and 101.325 kPa, the element Sn is
A
a liquid with a low vapour pressure
B
a reactive, colourless gas
C
a liquid with a high vapour pressure
D
a solid that is a poor conductor of heat
*E a solid that is a good conductor of electricity
9
o
A 10.0 L container has a sample of O2(g) at 25 C
and 51 kPa. A second 10.0 L container has a
o
sample of CH4(g), also at 25 C and 51 kPa.
Assuming ideal gas behaviour, which of the
following statements concerning these two samples
is correct?
12 A solution contains H2O2 in water. Complete
decomposition of the H2O2 in 170 g of this solution
o
yields 5.6 L of O2(g), measured at 0 C and
101.325 kPa. What is the percentage by mass of
H2O2 in this solution? Choose the closest answer.
*A 10%
(1) They contain the same number of molecules.
(2) They have the same density.
(3) The molecules in the two samples have the same
average kinetic energy.
A
(1) and (2)
B
(2) and (3)
(1) only
E
(3) only
20%
C
5.0%
D
3.0%
E
1.0%
13 A handbook gives the specific heat of copper (Cu)
−1 o −1
as 0.385 J g C . What is the specific heat
−1 −1
expressed in J g K ? Choose the closest value.
*C (1) and (3)
D
B
A
105 J g
−1
−1
K
−1
*B 0.385 J g
−1
10 What volume of 6.00 mol L HBr(aq) is required to
−1
make 1.00 L of 2.40 mol L HBr(aq)?
A
1.00 L
B
0.600 L
*C 0.400 L
D
0.200 L
E
0.167 L
−3
C
1.41×10
D
2.60 J g
E
9.51×10
−1
−3
−1
K
−1
Jg
−1
K
−1
K
−1
Jg
−1
K
14 Element X forms the stable compounds XS, XSO4
and X(NO3)3. Which of the following could X
represent?
11 The specific heats of gold and copper are 0.13 and
−1 o −1
0.39 J g C , respectively. If 1.0 g samples of each,
o
initially at 25 C, are placed in the same beaker of hot
water,
A
the copper will have the highest final temperature
B
the gold will absorb the greatest quantity of heat
A
carbon
B
magnesium
C
sodium
D
zinc
*E iron
15 Which of the following has a planar, triangular shape?
*C the copper will absorb the greatest quantity
of heat
−
*A NO3
D
the gold will have the highest final temperature
B
CO2
E
the temperature change for the copper will be
about three times that of the gold
C
NH3
D
BeH2
E
SO3
2−
© 2012 UNIVERSITY OF WATERLOO AVOGADRO EXAM / 3
16 What is the minimum mass of oxygen gas required to
react with exactly 20 grams of hydrogen gas,
assuming these gases react to form water? Choose
the closest answer.
20 What are the most probable products of the
combustion of CH3CH2SH in oxygen?
A
CH4 and H2S
CO2 and H2S
A
20 g
B
B
40 g
*C CO2, H2O and SO2
C
80 g
D
CO2, H2O and H2SO4
E
CH4, H2O and SO2
*D 160 g
E
320 g
21 How many moles of Cl2 are required to oxidize exactly
2+
3+
one mole of Fe to one mole of Fe ?
17 Typically, a binary salt may be formed between
*A 0.5 moles
A
an s-block cation and a d-block anion
B
a p-block cation and an s-block anion
C
a d-block cation and an s-block anion
D
a p-block cation and a d-block anion
B
1 mole
C
1.5 moles
D
2 moles
E
3 moles
*E an s-block cation and a p-block anion
−1
18 Where in the periodic table does one find the atoms
with the smallest atomic radius?
A
22 The pH of a 0.10 mol L aqueous solution is 5.1.
Which of the following might be the solute?
upper left
A
NaCl
B
HCl
C
HNO3
D
NH3
*B upper right
C
lower left
D
lower right
E
in the first long period (fourth row)
19 Which of the following pairs of substances are
allotropes?
A
CH3CH2OH and CH3OCH3
B
Fe(NO3)2 and Fe(NO3)3
C
NaCl and KCl
*E NH4Cl
23 The third ionization energy of an element, X, is the
energy required to
*D O2 and O3
E
234
U and
A
remove one mole of electrons from one mole of X
atoms
B
remove three moles of electrons from one mole of
X atoms
C
remove one mole of electrons from one mole of
3+
X ions
238
U
*D remove one mole of electrons from one mole of
2+
X ions
E
4 / AVOGADRO EXAM © 2012 UNIVERSITY OF WATERLOO
add three moles of electrons to one mole of X
atoms
28 What of the following is named copper (II) chloride?
24 What is the oxidation state of sulfur in H2S2O6?
A
+4
*A CuCl2
*B +5
C
+6
D
+7
E
+10
25 A 1.0 L sample of N2(g) has a pressure of exactly
100 kPa. A 2.0 L sample of O2(g) has a pressure
of 50 kPa at the same temperature. The samples
are mixed and forced into a 1.0 L container.
Assuming that no reaction occurs and that the
temperature remains constant, what is the final
pressure of the mixture?
B
Cu2Cl
C
(CuCl)2
D
CuCl
E
Cu2Cl2
29 What mass of Na2CO3 is needed to make 5.00 L of a
+
−1
solution having [Na ] = 0.100 mol L ?
A
0.500 g
B
5.30 g
10.6 g
A
25 kPa
C
B
50 kPa
*D 26.5 g
C
100 kPa
E
D
150 kPa
53.0 g
30 Which of the following statements concerning the
reaction below is true?
*E 200 kPa
Mg + CuSO4 → MgSO4 + Cu
26 Which of the following atoms has the greatest number
of unpaired electrons in its ground electronic state?
A
Magnesium is reduced.
B
Magnesium is the oxidizing agent.
C
Sulfur is oxidized.
*D Co
D
Sulfur is reduced.
E
*E Copper sulfate is the oxidizing agent.
A
Sc
B
Al
C
Si
Zn
−1
27 If 1.0 mol L NaX(aq) contains 7.4% solute by mass,
what is the molar mass of X? Choose the closest
answer. Assume the density of this solution is
approximately equal to that of water, 1.0 g/mL.
A
31 The noble gas atoms show only a limited tendency to
form covalent bonds with other atoms. Which of the
following pairs of atoms show the greatest tendency to
form a covalent bond?
−1
17 g mol
A
neon and fluorine
B
neon and iodine
−1
*B 51 g mol
C
−1
74 g mol
−1
D
98 g mol
E
120 g mol
−1
*C xenon and fluorine
D
xenon and cesium
E
xenon and iodine
© 2012 UNIVERSITY OF WATERLOO AVOGADRO EXAM / 5
32 A gaseous mixture consists of 25% H2, 25% N2,
25% O2 and 25% Cl2 by mass. Which gas has the
o
highest partial pressure at 227 C and 101 kPa?
Molar masses,
−1
(in g mol ):
2.016
H2,
28.02
N2,
32.00
O2,
Cl2,
70.90
*A H2
B
N2
C
O2
D
Cl2
E
The partial pressures are equal.
−1
35 When 0.100 L of 1.00 mol L HCl(aq) is mixed with
−1
0.100 L of 1.00 mol L NaOH, the temperature of
o
the solution rises by 8.5 C. Assuming no heat loss
to the container or the surroundings, what is the heat
of reaction for the following reaction? (You may also
assume that, for these aqueous solutions, the
−1
density is about 1.0 g mL and the heat capacity is
−1 o −1
about 4.2 J g C .)
−
H (aq) + OH (aq) → H2O(l)
+
−1
33 In an experiment,1.0 mol L HCl(aq) is added
−1
millilitre-by-millilitre to 50.0 mL of 1.0 mol L
NaOH(aq) until the total volume reaches 150.0 mL.
Which of the following statements concerning this
experiment is correct?
−1
A
−4.8 kJ mol
B
−7.1 kJ mol
C
−18 kJ mol
D
−36 kJ mol
−1
−1
−1
−1
A
The pH increases approximately linearly with the
volume of HCl added.
B
The pH decreases approximately linearly with the
volume of HCl added.
C
Initially, the pH decreases approximately linearly
with the volume of HCl added, and then decreases
abruptly as the total volume approaches 50.0 mL.
*E −71 kJ mol
36 Which expression correctly represents a chemical
reaction between calcium hydroxide and carbon
dioxide?
A
*B Ca(OH)2 + CO2 → CaCO3 + H2O
*D Initially, the pH decreases approximately linearly
with the volume of HCl added, and then decreases
abruptly as the total volume approaches 100.0 mL.
E
Initially, the pH increases approximately linearly
with the volume of HCl added, and then increases
abruptly as the total volume approaches 100.0 mL.
34 An oxide of potassium contains 45.0% oxygen by
mass. What is the simplest formula of this oxide?
A
KO
B
K2O
CaOH + CO2 → CaHCO2
C
Ca(OH)2 + CO2 → CaHCO3 + H2O
D
2 CaOH + 2 CO2 → 2 CaCO3 + H2O
E
Ca(OH)2 + 2 CO2 → Ca(CO3)2 + H2O
37 Which of the following pairs of atoms will form a bond
with the greatest covalent character?
A
carbon and oxygen
B
hydrogen and oxygen
C
carbon and chlorine
D
hydrogen and chlorine
*C KO2
D
K2O3
E
KO3
6 / AVOGADRO EXAM © 2012 UNIVERSITY OF WATERLOO
*E hydrogen and carbon
38 If an element X forms an oxide with the formula XO2,
then what is the expected formula for the fluoride of
element X?
A
XF
B
XF2
C
XF3
*D XF4
E
X2F
39 A 0.9300 g sample of a mixture of NaCl and MgCl2
was dissolved in water. Addition of excess
AgNO3(aq) caused all of the chloride ion to precipitate
as AgCl(s). The dry precipitate weighed 2.676 g.
What was the percentage by weight of NaCl in the
original mixture?
A
between 0 and 19.9%
*B between 20.0 and 39.9%
C
between 40.0 and 59.9%
D
between 60.0 and 79.9%
E
between 80.0% and 100%
Molar masses
(in g mol−1):
NaCl,
58.44
MgCl2, 95.21
AgCl, 143.35
40 If the Kelvin temperature of a gas increases by a
factor of four, then the average speed of molecules
A
increases by a factor of four
B
decreases by a factor of four
*C increases by a factor of two
D
decreases by a factor of two
E
is unchanged
© 2012 UNIVERSITY OF WATERLOO AVOGADRO EXAM / 7
DATA SHEET
AVOGADRO EXAM 2012
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
24.31
20
Ca
40.08
38
Sr
87.62
56
Ba
137.3
88
Ra
226
3
4
3B
4B
21
22
Sc
Ti
44.96 47.88
39
40
Y
Zr
88.91 91.22
57-71
72
La-Lu
Hf
178.5
89-103 104
Ac-Lr
Rf
57
La
138.9
89
Ac
(227)
58
Ce
140.1
90
Th
232.0
5
5B
23
V
50.94
41
Nb
92.91
73
Ta
180.9
105
Db
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
Ds
62
63
64
Sm
Eu
Gd
150.4 152.00 157.3
94
95
96
Pu
Am
Cm
(244) (243) (247)
Constants:
mol−1
6.022 × 10
R
=
0.082058 atm L K−1 mol−1
=
8.3145 kPa L K−1 mol−1
=
8.3145 J K−1 mol−1
23
−14
Kw =
1.0×10
F
96 485 C mol
Equations:
65
Tb
158.9
97
Bk
(247)
12
2B
30
Zn
65.38
48
Cd
112.4
80
Hg
200.6
112
Cn
66
Dy
162.5
98
Cf
(251)
67
Ho
164.9
99
Es
(252)
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)
71
Lu
175.0
103
Lr
(260)
Conversion factors:
NA =
=
11
1B
29
Cu
63.55
47
Ag
107.9
79
Au
197.0
111
Sg
13
3A
5
B
10.81
13
Al
26.98
31
Ga
69.72
49
In
114.8
81
Tl
204.4
1 atm = 101.325 kPa = 760 Torr = 760 mm Hg
o
0 C = 273.15 K
(at 298 K)
−1
PV = nRT
k t1/2 = 0.693
pH = pKa + log ( [base] / [acid] )
8 / AVOGADRO EXAM © 2012 UNIVERSITY OF WATERLOO
x=
−b ± b 2 − 4ac
2a
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)