Download 2011

University of KwaZulu-Natal, Westville Campus, Durban
Examinations: May 2011
GENERAL PRINCIPLES OF CHEMISTRY – CHEM 110
Section A – SHORTENED VERSION
Total Marks for Section A: 45
Total Marks for Examination: 100
Duration: 3 Hours
Internal Examiners: Dr P.H. Coombes; Mrs H. Govender; Dr B. Moodley; Professor B.S. Martincigh
Moderating Board: Professor H.G. Kruger; Dr M. Akerman; Dr C. Southway; Dr W.E. van Zyl
1.
2.
3.
Carbon dioxide, CO2(g), is an example of
A)
a homogeneous mixture
B)
a compound
5.
6.
an element
a heterogeneous mixture
Which of the following involves a physical change?
A)
the formation of table salt, NaCl(s), from HCl and NaOH
B)
the combustion of butane, C4H10(g)
C)
the inability of gold, Au(s), to react with hydrochloric acid, HCl(aq)
D)
the freezing of water, H2O(l)
(1)
(1)
Which of the following masses are equivalent to a mass of 1.00 g?
I.
4.
C)
D)
1.00 x 103 mg II.
1.00 x 10-4 kg
III.
1.00 x 106 µg
A)
I and II
C)
II and III
B)
I and III
D)
all of them
The volume of 30.0 g of ethanol (C2H6O(l), density = 0.789 g mL-1) is
A)
26.3 mL
C)
0.380 L
B)
33.3 mL
D)
38.0 mL
The numbers of protons, neutrons, and nucleons present in an atom of the platinum isotope
194
Pt
are
A)
78 protons, 116 neutrons, 194 nucleons
B)
78 protons, 38 neutrons, 116 nucleons
C)
116 protons, 78 neutrons, 194 nucleons
D)
78 protons, 194 neutrons, 78 nucleons
The mass of one molecule of the painkiller codeine, C18H21NO3, is
A)
299.358 u
C)
320.526 u
B)
299.4 u
D)
468.8 u
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School of Chemistry, University of KwaZulu-Natal, Westville Campus
Examinations: May 2011
CHEM 110: General Principles of Chemistry
Section A
7.
8.
9.
10.
The % hydrogen (m/m) in the drug Verapamil (C27H38N2O4, 454.6 g mol-1) is
A)
0.2217 %
C)
8.426 %
B)
2.632 %
D)
16.85 %
(1)
How many moles of K3PO4 are required to produce 9 moles of KCl by the following reaction:
3CaCl2(aq) + 2K3PO4(aq) → Ca3(PO4)2(s) + 6KCl(aq)?
A)
1
C)
3
B)
2
D)
4
(1)
Choose the correct answer from the following:
A)
730 mmHg = 101325 Pa
B)
18 Torr = 1.013 × 105 N m-2
(1)
C)
D)
433 Torr = 433 mmHg
760 mmHg = 10 atm
Carry out the following mathematical operations and report the answer to the correct number of
significant figures.
5.26 x 10-3 × 0.08206 × (273.15 + 32)
4.5469
A)
B)
11.
C)
D)
0.03
0.0290
(1)
C)
D)
all of them
IV only
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A strong electrolyte is one that __________ completely in aqueous solution.
A)
reacts
C)
disappears
B)
associates
D)
ionizes
(1)
Which of the following are combination reactions?
I.
CH4(g) + O2(g) → CO2(g) + H2O(l)
II.
CaO(s) + CO2(g) → CaCO3(s)
III.
Mg(s) + O2(g) → MgO(s)
IV.
PbCO3(s) → PbO(s) + CO2(g)
A)
B)
12.
13.
0.02895
0.029
I, II, and III
II and III
When aqueous solutions of AgNO3 and KI are mixed, the balanced net ionic
equation is
–
A)
Ag+(aq) + I (aq) → AgI(s)
B)
Ag+(aq) + NO3 (aq) → AgNO3(s)
C)
D)
Ag+(aq) + NO3 (aq) → AgNO3(aq)
AgNO3(aq) + KI(aq) → AgI(s) + KNO3(aq)
–
–
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School of Chemistry, University of KwaZulu-Natal, Westville Campus
Examinations: May 2011
CHEM 110: General Principles of Chemistry
Section A
14.
Which are the spectator ions in the reaction between KOH(aq) and HNO3(aq)?
–
A)
K+ and H+
C)
K+ and NO3
B)
15.
16.
–
H+ and OH
D)
H+ and NO3
–
(1)
What mass of methanol, CH3OH(l), must be added to water to make 150 mL of a
2.0 M CH3OH(aq) solution?
A)
2.4 g
C)
4.3 g
B)
3.5 g
D)
9.6 g
(1)
As one mole of any gas will occupy a volume of 22.414 L under STP conditions
A)
all gases have the same molecular mass.
B)
the molecules of all gases will have the same velocities at STP.
C)
all gases are diatomic.
D)
one mole of any gas will always have the same number of molecules.
(1)
17.
Air is sealed in a vessel at 273 °C and then cooled to 0 °C. If the vessel itself does not contract, the
pressure inside the vessel will become
A)
one-fourth of its original value.
B)
one-half of its original value.
C)
twice its original value.
D)
zero.
(1)
18.
Iron has an oxidation number of +6 in
A)
Fe3O4
C)
Fe(CN)6
B)
D)
Fe2O3
19.
BaFeO4
4–
(1)
In the chemical reaction,
Zn(s) + CuSO4(aq) → ZnSO4(aq) + Cu(s),
A)
B)
C)
D)
20.
metallic zinc is the reducing agent.
metallic zinc is reduced.
copper ion is oxidized.
sulfate ion is the oxidizing agent.
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2+
According to the Aufbau principle, the ground state electron configuration for the Sn ion is
1
10
1
2
10
2
A)
[Kr]5s 4d 5p
B)
[Kr]5s 4d 5p
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2
10
2
10
C)
[Kr]5s 4d
D)
[Kr]5p 4d
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School of Chemistry, University of KwaZulu-Natal, Westville Campus
Examinations: May 2011
CHEM 110: General Principles of Chemistry
Section A
21.
22.
23.
Which is the correct ground-state electron configuration for silver?
C)
[Kr]5s24d10
A)
[Kr]5s24d9
B)
[Kr]5s14d10
D)
[Xe]5s24d9
(1)
Which set of quantum numbers is correct and consistent with n = 4?
A)
l = 3; ml = – 3; ms = + ½
C)
l = 2; ml = +3; ms = + ½
B)
l = 4; ml = +2; ms = – ½
D)
l = 3; ml = –3; ms = + 1
(1)
The correct Lewis structure for potassium sulfide is:
A)
2K+ S
B)
K+ S
C)
K S K
D)
K S
2-
2-
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24.
25.
The order of increasing polarity of the bonds: C-H, H-F, H-Br, is
A)
C-H < H-F < H-Br
C)
H-Br < C-H < H-F
B)
C-H < H-Br < H-F
D)
H-Br < H-F < C-H
The order of repulsive forces that affects the bond angles in VSEPR is:
A)
lone pair – lone pair > bond pair – bond pair > lone pair – bond pair
B)
lone pair – lone pair > lone pair – bond pair > bond pair – bond pair
C)
bond pair – bond pair > lone pair – bond pair > lone pair – lone pair
D)
bond pair – bond pair > lone pair – lone pair > lone pair – bond pair
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26.
According to VSEPR theory, if there are three electron domains in the valence shell of an atom, their
electron domain geometry will be:
A)
octahedral
C)
trigonal bipyramidal
B)
linear
D)
trigonal planar
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27.
What kind/s of intermolecular forces exist between H2S molecules?
A)
hydrogen bonding only
B)
C)
D)
dipole-dipole interactions only
both dipole-dipole interactions and hydrogen bonding
dipole-dipole interactions and dispersion forces
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School of Chemistry, University of KwaZulu-Natal, Westville Campus
Examinations: May 2011
CHEM 110: General Principles of Chemistry
Section A
28.
Hexane has a boiling point of 69 °C while 2,2-dimethylbutane has a boiling point of 49.7 °C.
CH3
CH3CH2CH2CH2CH2CH3
H3 C
hexane
2,2-
C
CH2 CH3
CH3 dimethylbutane
Hexane has a higher boiling point because:
A)
hexane has dipole-dipole interactions.
B)
hexane has more surface area for interacting with neighbouring hexane molecules.
C)
hexane has hydrogen bonding.
D)
hexane has less surface area for interacting with neighbouring hexane molecules.
29.
Arrange the following molecules in increasing order of surface tension.
CH3CH2CH2OH
A)
B)
C)
D)
30.
31.
(1)
HOCH2CH(OH)CH2OHHOCH2CH2OH
CH3CH2CH2OH < HOCH2CH(OH)CH2OH < HOCH2CH2OH
CH3CH2CH2OH < HOCH2CH2OH < HOCH2CH(OH)CH2OH
HOCH2CH2OH < CH3CH2CH2OH < HOCH2CH(OH)CH2OH
HOCH2CH2OH < HOCH2CH(OH)CH2OH < CH3CH2CH2OH
Which of the following has the highest boiling point?
N2, Br2, H2, Cl2
A)
N2
B)
Br2
C)
D)
H2
Cl2
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(1)
Two chemical pollutants, CO(g) and NO(g), can be converted to less harmful gases by the following
reaction:
CO(g) + NO(g) → CO2(g) + ½N2(g)
If,
CO(g) + ½O2(g) → CO2(g)
2NO(g) → N2(g) + O2(g)
∆H = – 283.0 kJ
∆H = – 180.6 kJ
then ∆H for the reaction to convert CO(g) and NO(g) is:
A)
– 373.3 kJ
C)
B)
– 463.6 kJ
D)
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– 192.7 kJ
+ 192.7 kJ
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School of Chemistry, University of KwaZulu-Natal, Westville Campus
Examinations: May 2011
CHEM 110: General Principles of Chemistry
Section A
32.
For the reaction
2NO2(g) 2NO(g) + O2(g),
Kc = 1.8 × 10-6 at 184 °C. What is the value of Kc for the reaction
NO(g) + ½O2(g) NO2(g) at this temperature?
A)
B)
33.
0.9 × 106
7.5 × 102
C)
D)
5.6 × 105
2.8 × 105
(1)
NOCl decomposes according to the equation
2NOCl(g) Cl2(g) + 2NO(g).
If 3.0 mol of NOCl is placed in a 1.0 dm3 vessel, after reaction, the equilibrium mixture is found to
contain 1.0 mol NOCl. What is Kc for this reaction?
A)
16
C)
8.0
B)
4.0
D)
0.25
(2)
34.
The oxidation of carbon monoxide is shown below.
2CO(g) + O2(g) 2CO2(g)
∆H° = – 133.5 kJ
Which of the following will cause an increase in the equilibrium concentration of CO?
A)
Increasing the pressure of the system at constant temperature.
B)
Adding more O2 to the system.
C)
Removing CO2 from the system as it is formed.
D)
Increasing the temperature of the system.
35.
Given: C(s) + CO2(g) 2CO(g). At equilibrium at a certain temperature, the partial pressures of
CO and CO2 are 1.22 and 0.780 atm respectively. Calculate Kp for this reaction.
A)
3.13
C)
1.56
B)
0.64
D)
1.91
36.
37.
(1)
(1)
–
The conjugate acid of HCO3 is
A)
H2O
B)
H3O+
C)
H2CO3
D)
CO32⁻
Which of the following weak acids has the anion that is the strongest base?
A)
CH3COOH (Ka = 1.8 × 10-5)
C)
HF (Ka = 6.8 × 10-4)
-8
B)
HClO (Ka = 3.0 × 10 )
D)
HCN (Ka = 4.8 × 10-10)
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School of Chemistry, University of KwaZulu-Natal, Westville Campus
Examinations: May 2011
CHEM 110: General Principles of Chemistry
Section A
38.
Calculate the concentration of OH⁻, in mol dm-3, for an aqueous solution with a pH of 9.45.
A)
B)
39.
40.
2.8 × 10-5
3.5 × 10-10
C)
D)
0.78
2.8 × 109
Kw for water at 37 °C is 5.00 × 10-14. The pH of a neutral aqueous solution at this temperature is
A)
7.00
C)
6.65
B)
6.00
D)
7.35
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(1)
The oxidation of ammonia produces nitrogen and water,
4NH3 + 3O2 → 2N2 + 6H2O.
If the rate of formation of N2 is 2.0 mol dm-3 s-1, then the rate at which
A)
H2O is being formed is 2.0 mol dm-3 s-1.
B)
NH3 reacts is 4.0 mol dm-3 s-1.
C)
O2 reacts is 1.5 mol dm-3 s-1.
D)
H2O is being formed is 0.67 mol dm-3 s-1.
41.
(1)
The equation and the rate law for the reaction between NO(g) and H2(g) are:
2NO(g) + 2H2(g) → N2(g) + 2H2O(g)
Rate = k[NO]2[H2].
The overall reaction order is:
A)
1
C)
3
B)
D)
4
2
(1)
42.
Which of the following statements is false?
A)
Generally, the rate law cannot be deduced from the reaction stoichiometry.
B)
An elementary process is a chemical reaction that occurs in a single step.
C)
The rate law for an elementary process can be written directly from the stoichiometry of the
process.
D)
The rate law must be deduced from the overall reaction stoichiometry to be correct.
(1)
43.
Consider the mechanism:
O3(g) O2(g) + O(g)
O(g) + O3(g) → 2O2(g)
Intermediate/s in this reaction is/are:
A)
O(g)
B)
O3(g)
C)
D)
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O2(g) and O(g)
O2(g)
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