Download School of Chemistry and Physics Westville Campus, Durban

School of Chemistry and Physics
Westville Campus, Durban
BARCODE
Examination: May 2012
CHEM 110: GENERAL PRINCIPLES OF CHEMISTRY
Total Marks for Section A: 60
Duration: 3 Hours
Total marks for Examination: 100
Internal Examiners: Dr P Ndungu, Dr V Paideya, Mrs H Govender, Ms G Dawson
Moderators:
Dr M Akerman, Dr D Reddy, Dr S Ojwach, Dr C Southway
IMPORTANT: Complete this part immediately.
Student No.
Seat Number:
Name (optional)
INSTRUCTIONS:
1.
2.
3.
4.
5.
6.
7.
8.
Answer ALL questions.
Calculators may be used.
The pages of this paper must not be unpinned.
Your answers must be written on the MCQ sheet provided.
Use HB Pencil and Tipp-ExTM are not allowed.
This is Section A: Multiple Choice Questions, consisting of 18 pages.
You are advised to spend not more than 2 hours on Section A.
A periodic table and a data sheet are provided at the end of the Multiple Choice Questions
Section
Maximum
Internal
Mark
External
Mark
Section B
Section
A
1
2
3
4
5
6
7
8
9
10
Total
60
3
4
4
5
1
4
4
6
4
5
40
Total
100
School of Chemistry and Physics
University of KwaZulu-Natal, Westville Campus
CHEM110/195: General Principles of Chemistry
May 2012 Examination
SECTION A: Multiple Choice Questions
1.
What is the volume of 30.0 g of methanol (CH3OH(l), density = 0.791 g mL-1)?
A
26.3 mL
B
33.3 mL
C
0.379 L
D
37.9 mL
(1)
2.
Classify the following substances
(i) copper oxide (ii) copper metal (iii) copper alloy
As an element, compound, homogeneous mixture or heterogeneous mixture.
A
(i) heterogeneous
(ii) compound
(iii) element
B
(i) heterogeneous
(ii) compound
(iii) homogeneous
C
(i) compound
(ii) element
(iii) homogeneous
D
(i) homogeneous
(ii) element
(iii) heterogeneous
(2)
3.
Indicate how many significant figures are present in the following quantity?
0.06060 mL
A
2
B
4
C
3
D
5
(1)
Page 2 of 18
School of Chemistry and Physics
University of KwaZulu-Natal, Westville Campus
CHEM110/195: General Principles of Chemistry
May 2012 Examination
4.
Calculate the following arithmetic functions and round off your answers to the correct
number of significant figures:
2.78 x 5.903 ÷ (6.489 – 5.01)
A
11.1
B
11.08
C
11.081
D
11.0811
(2)
5.
How many protons, neutrons, and nucleons are present in an atom of the platinum
isotope 194Pt?
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
(1)
6.
Calculate the mass of 1.16 x 1022 molecules of N2
A
145.3 g N2
B
0.270 g N2
C
0.540 g N2
D
1453 g N2
(1)
Page 3 of 18
School of Chemistry and Physics
University of KwaZulu-Natal, Westville Campus
CHEM110/195: General Principles of Chemistry
May 2012 Examination
7.
The chemical formula for copper(I) phosphate is:
A
Cu2PO4
B
Cu2PO3
C
Cu3PO4
D
CuPO
(1)
8.
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
I, II, and III
B
II and III
C
all of them
D
IV only
(1)
9.
Using IUPAC rules give the name of Fe2S3
A
Iron sulfide
B
Iron(III) sulfide
C
Iron(III) sulfate
D
Ferric(II) sulfate
(1)
Page 4 of 18
School of Chemistry and Physics
University of KwaZulu-Natal, Westville Campus
CHEM110/195: General Principles of Chemistry
May 2012 Examination
10.
Give the formula for Dinitrogen pentoxide
A
N2P2O5
B
N2O5
C
NO5
D
N2PO5
(1)
11.
2.0 mole of silver nitrate reacts with 1.6 moles of HCl in a precipitation reaction to
produce AgCl and nitric acid. The following reaction occurred:
AgNO3(aq) + HCl(aq)  AgCl(s) + HNO3(aq)
How many moles of HNO3 are produced?
A
1.6
B
1.0
C
1.8
D
0.4
(1)
12.
The % (m/m) hydrogen in Asprin (C9H8O4, 180.2 g mol-1) is
A
0.0441 %
B
4.475 %
C
4.45 %
D
0.022 %
(1)
Page 5 of 18
School of Chemistry and Physics
University of KwaZulu-Natal, Westville Campus
CHEM110/195: General Principles of Chemistry
May 2012 Examination
13.
Ethyl acetate is composed of 54.4% C, 9.17% H and 36.39% O by mass.
The empirical formula of ethyl acetate is:
A
CH2O
B
C4H8O2
C
C2H4O
D
None of the above
(2)
14.
Determine the molecular formula for adipic acid if it has an empirical formula of C3H5O,
and a molecular mass of 114.1 u.
A
C3H5O
B
C5H6O3
C
C9H15O
D
C6H10O2
(2)
15.
You are provided with 1.00 mol of Mg and 0.813 mol of iron(III) oxide. The balanced
equation for the reaction is:
3Mg + Fe2O3 → 3MgO + 2Fe
What is the limiting reagent for the production of MgO?
A
Mg
B
Fe2O3
C
MgO
D
Fe
(2)
Page 6 of 18
School of Chemistry and Physics
University of KwaZulu-Natal, Westville Campus
CHEM110/195: General Principles of Chemistry
May 2012 Examination
16.
Which of these compounds is insoluble in water?
A
Ni(NO3)2
B
PbCl4
C
AgCl
D
FeSO4
(1)
17.
Which of the following pairs of aqueous solutions will give a precipitate when mixed?
A
CaCO3 and HCl
B
Mg(NO3)2 and NaOH
C
AgNO3 and Ca(ClO4)2
D
NaOH and CH3COOH
(1)
18.
Consider the following equation and select the correct products
FeS(s) + 2H+(aq) →
2+
A
H2S(s) + Fe (aq)
B
H2S(aq) + Fe(s)
C
H2S(g) + Fe (aq)
D
no reaction occurs
2+
(1)
Page 7 of 18
School of Chemistry and Physics
University of KwaZulu-Natal, Westville Campus
CHEM110/195: General Principles of Chemistry
May 2012 Examination
19.
In the reaction between aqueous copper(II) sulfate and sodium carbonate, which are
the so-called "spectator" ions?
2+
A
Cu and CO32-
B
Na and SO4
C
Na and CO32-
D
None of the above
+
2-
+
(2)
20.
Identify the reducing agent in the following balanced reaction:
3SO32–(aq) + 2MnO4–(aq) + 2H+(aq)  3SO42–(aq) + 2MnO2 + H2O
A
SO32–
B
MnO4–
C
SO42–
D
MnO2
(1)
21.
Real gases are most like ideal gases at
A
high pressure and high temperature.
B
high pressure and low temperature.
C
low pressure and high temperature.
D
low pressure and low temperature.
(1)
Page 8 of 18
School of Chemistry and Physics
University of KwaZulu-Natal, Westville Campus
CHEM110/195: General Principles of Chemistry
May 2012 Examination
22.
Which one of the following sets of quantum numbers is NOT allowed?
A
n = 3, ℓ = 2, mℓ = 1
B
n = 3, ℓ = 0, mℓ = 0
C
n = 3, ℓ = 3, mℓ = 1
D
n = 3, ℓ = 2, mℓ = -1
(1)
23.
Which pair of particles has the same number of electrons?
–
2+
A
F , Mg
B
Br , Se
C
Ne, Ar
D
Al , P
–
3+
3–
(1)
24.
An atom of Fe has two 4s electrons and six 3d electrons. How many unpaired
electrons would there be in an atom of iron?
A
one
B
two
C
three
D
four
(1)
Page 9 of 18
School of Chemistry and Physics
University of KwaZulu-Natal, Westville Campus
CHEM110/195: General Principles of Chemistry
May 2012 Examination
25.
The ground state electron distribution for the Sn
10
1
1
10
2
2
10
2
10
2
A
[Kr]4d 5s 5p
B
[Kr]4d 5s 5p
C
[Kr]4d 5s
D
[Kr]4d 5p
2+
ion is
(1)
26.
2+
+
Cadmium normally forms the ion Cd , whereas silver gives the Ag ion. What is an
explanation of these facts?
A
Silver has two 5s electrons, one of which is more difficult to remove than the
other.
B
The 4d subshell in silver is completed to give a more stable structure, leaving
only one electron in the 5s subshell.
C
Cadmium loses two 4d electrons to form the Cd2+ ion.
D
None of these is correct.
(1)
27.
Which is the correct Lewis structure for CS2?
:C
S
: :
A
S:
S:
:C
S
:
:S
C
:
C
D
:S
C
: :
:
:
B
S:
S:
(2)
Page 10 of 18
School of Chemistry and Physics
University of KwaZulu-Natal, Westville Campus
CHEM110/195: General Principles of Chemistry
May 2012 Examination
28.
Which of the following atoms or ions has eight valence electrons?
A
Kr
B
CI
C
Na+
D
All of the above
–
(2)
29.
Which of the molecules below has the most polar bond?
A
HI
B
HBr
C
HCl
D
HF
(1)
30.
Which structure does not obey the octet rule?
A
SbF3
B
NF3
C
PF3
D
IF3
(2)
31.
Which of the following molecules has a square planar geometry?
A
PH3
B
XeF2
C
ICl3
D
XeF4
(1)
Page 11 of 18
School of Chemistry and Physics
University of KwaZulu-Natal, Westville Campus
CHEM110/195: General Principles of Chemistry
May 2012 Examination
32.
An electron domain consists of
i)
a nonbonding pair of electrons
ii)
a single bond
iii)
a multiple bond
A
i only
B
ii only
C
iii only
D
i, ii, and iii
(1)
33.
For which of the following molecules, shown below, is the molecular geometry (shape)
the same as the VSEPR electron domain arrangement (electron domain geometry)?
(i) PCl3
A
(i) and (ii)
B
(iii) and (iv)
C
(i) and (iv)
D
(ii) and (iv)
(ii) CCl4
(iii) XeF4
(iv) SF6
(2)
34.
For which one of the following elements is ΔHf° not zero?
A
O2(g)
B
Cl2(g)
C
F2 (s)
D
C (graphite)
(1)
Page 12 of 18
School of Chemistry and Physics
University of KwaZulu-Natal, Westville Campus
CHEM110/195: General Principles of Chemistry
May 2012 Examination
35.
For which one of the following reactions is the value of ΔH°rxn equal to ΔHf° for the
product?
A
½N2(g) + O2(g) → NO2(g)
B
H2(g) + ½O2(g) → H2O(l)
C
2C(s, graphite) + 2H2(g) → C2H4(g)
D
All of the above
(1)
36.
Which substance in the reaction below either appears or disappears the fastest?
4NH3 + 7O2  4NO3 + 6H2O
A
H2O
B
O2
C
NH3
D
The rates of appearance/disappearance are the same for all of these.
(1)
37.
Which of the following units cannot be used as a valid unit to express a reaction rate
A
mol/hr
B
mol/L hr
C
M/s
D
mol/L
(1)
Page 13 of 18
School of Chemistry and Physics
University of KwaZulu-Natal, Westville Campus
CHEM110/195: General Principles of Chemistry
May 2012 Examination
38.
With regards to the reaction quotient of a reaction (Q) and the equilibrium constant K eq,
choose the correct statement below:
A
Keq does not change with temperature, whereas Q is temperature dependent.
B
Keq depends on the concentrations or partial pressures of reaction components.
C
Q does not depend on the concentrations or partial pressures of reaction
components.
D
Q is the same as Keq when a reaction is at equilibrium.
(1)
39.
Which of the following equilibria, will shift to the left in response to a decrease in
volume?
A
H2(g) + Cl2(g) ⇌ 2HCl(g)
B
N2(g) + 3H2(g) ⇌ 2NH3(g)
C
2SO3(g) ⇌ 2SO2(g) + O2(g)
D
4Fe(s) + 3O2(g) ⇌ 2Fe2O3(s)
(2)
40.
Complete the following statement by selecting the appropriate letter below.
The effect of a catalyst on an equilibrium is to ________.
A
shift the equilibrium to the right.
B
increase the rate at which equilibrium is achieved without changing the
composition of the equilibrium mixture.
C
slow the reverse reaction only.
D
increase the rate of the forward reaction only
.
(1)
Page 14 of 18
School of Chemistry and Physics
University of KwaZulu-Natal, Westville Campus
CHEM110/195: General Principles of Chemistry
May 2012 Examination
41.
The value of ΔH° for the reaction below is –1107 kJ:
2Ba(s) + O2(g)  2BaO(s)
Calculate the amount of heat released when 5.75 g of Ba(s) reacts completely with
oxygen to form BaO(s).
A
26.3kJ
B
96.3kJ
C
46.4kJ
D
23.2kJ
(2)
42.
Select the correct statement:
A
Electronegativity decreases from left to right along a row of the periodic table,
and increases from top to bottom within a group
B
Electronegativity increases from left to right along a row of the periodic table,
and increasesfrom top to bottom within a group
C
Electronegativity increases from left to right along a row of the periodic table,
and decreases from top to bottom within a group
D
Electronegativity increases from left to right along a row of the periodic table,
and stays the same from top to bottom within a group
(1)
Page 15 of 18
School of Chemistry and Physics
University of KwaZulu-Natal, Westville Campus
CHEM110/195: General Principles of Chemistry
May 2012 Examination
43.
Calculate the formal charge on N in the nitrate anion:
A
+1
B
0
C
-1
D
+2
(1)
44.
Which statement is incorrect?
A
Resonance structures are equivalent Lewis diagrams (structures) used to
represent one molecule.
B
Formal charge is used as a guideline to determine the most accurate Lewis
structure out of a number of different possibilities.
C
Formal charge can always be used to determine the actual charge on an atom
in a molecule.
D
Lewis structures are a simplified model that illustrates how valence electrons
are shared between covalent compounds.
(1)
Page 16 of 18
School of Chemistry and Physics
University of KwaZulu-Natal, Westville Campus
CHEM110/195: General Principles of Chemistry
May 2012 Examination
45.
If the rate law for the reaction
2A + 3B  products
is first order in A and second order in B, then the rate law is:
A
Rate = k[A][B]
B
Rate = k[A][B]2
C
Rate = k[A]2[B]
D
Rate = k{A]2[B]2
(1)
46.
The kinetics of the reaction below were studied and it was determined that the reaction
rate increased by a factor of 9 when the concentration of B was tripled. What is the
order with respect to B?
A+BP
A
Second
B
First
C
Zero
D
One-Half
(1)
47.
Calculate the [H+] concentration, in mol dm-3, for an aqueous solution with a pH of 4.56.
A
2.75 × 10-5
B
3.5 × 10-10
C
0.78
D
2.8 × 109
(1)
Page 17 of 18
School of Chemistry and Physics
University of KwaZulu-Natal, Westville Campus
CHEM110/195: General Principles of Chemistry
May 2012 Examination
48.
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
B
6.00
C
6.65
D
7.35
(1)
[Total Marks: 60]
End of Section A
Page 18 of 18