COLLEGE OF ENGINEERING
PUTRAJAYA CAMPUS
FINAL EXAMINATION
TRIMESTER 2, 2009/2010
PROGRAMME
:
Foundation in Engineering
SUBJECT CODE
:
CHEF 114/CHEB 114
COURSE CODE
:
Chemistry I
DATE
:
8 February 2010
DURATION
:
9.00 am – 12.00 pm (3 hours)
INSTRUCTIONS TO CANDIDATES:
1.
Answer ALL the questions in Sections A and B and any FOUR (4) out of FIVE (5)
questions from Section C.
2.
Please mark the answers for Section A in the answer sheet.
3.
Write the answers for Sections B and C in the answer booklet.
4.
All calculations in Sections B and C must be shown clearly (wherever applicable) in order
to get full marks.
5.
Please detach the answer sheet for Section A from this question booklet and fasten it
together with the answer booklet containing answers from Sections B and C.
6.
Periodic Table of elements and Standard Reduction Potential Table are provided.
7.
No reference books, papers and mobile phones are allowed into the examination hall.
THIS QUESTION PAPER CONSISTS OF 17 PRINTED PAGES INCLUDING THIS COVER PAGE
CHEF 114, Trimester2 2009/2010
SECTION A
Multiple Choice Questions. There is ONE best response to each question. Read all responses,
choose the best one and write it on your answer booklet. Blacken the circle on the answer sheet
on page 17 corresponding to this answer.
Answer ALL questions. (1 mark for each question)
1.
An atom of helium-4 differs from an atom of lithium-7 because the atom of helium-4 has
________ than the atom of lithium-7.
2.
A.
one more proton
D.
two less neutrons
B.
one more neutron
E.
three more electrons
C.
two less protons
Glycine, one of the essential amino acids, has two carbon atoms, five hydrogen atoms, two
oxygen atoms, and one nitrogen atom per molecule. Its molecular formula is written as
3.
A.
C2H5NO2
D.
CHNO2
B.
Ca2H5NO2
E.
Co2H5NO2
C.
C2H5NeO2
The original method of making ammonia was to react calcium cyanamide with water
according to the following reaction.
_____ CaCN2(s) + _____ H2O(ℓ) → _____ CaCO3(s) + _____ NH3(g)
Which of the following is the most correct set of stoichiometric coefficients to balance this
equation?
A.
2, 6, 2, 4
D.
1, 1, 1, 1
B.
4, 2, 6, 2
E.
2, 3, 2, 1
C.
1, 3, 1, 2
Page 2 of 17
4.
Ammonia gas can be prepared by the reaction of a basic oxide such as calcium oxide with
ammonium chloride, an acidic salt.
CaO(s) + 2 NH4Cl(s) → 2 NH3(g) + H2O(g) + CaCl2(s)
If you isolate exactly 100 g of NH3, but should have isolated 136 g in theory, what is the
percentage yield of ammonia in your experiment ?
5.
6.
A.
36.8%
D.
71.2%
B.
73.5%
E.
26.5%
C.
90.0%
How many molecules of N2 gas can be present in a 2.5 L flask at 50C and 650 mmHg?
A.
2.1  10-23 molecules
D.
3.6  1025 molecules
B.
4.9  1022 molecules
E.
0.081 molecules
C.
3.1  1023 molecules
Samples of the following volatile liquids are opened simultaneously at one end of a room.
If you are standing at the opposite end of this room, which species would you smell first?
[Assume that your nose is equally sensitive to all these species]
A.
ethyl acetate (CH3COOC2H5)
B.
camphor (C10H16O)
C.
diethyl ether (C2H5OC2H5)
D.
naphthalene (C10H8)
E.
pentanethiol (C5H11SH)
CHEF 114, Trimester2 2009/2010
7.
How many degrees of temperature rise will occur when a 25.0 g block of aluminum
absorbs 10.0 kJ of heat? The specific heat of Al is 0.900 J/g·C.
8.
A.
0.44C
D.
360C
B.
22.5C
E.
444C
C.
225C
To which one of these reactions below occurring at 25C refer to Hf [H2SO4(l)] ?
A. 2H(g) + S(g) + 4O(g)  H2SO4(l)
B. H2(g) + S(g) + 2O2(g)  H2SO4(l)
C. H2SO4(l)  H2(g) + S(s) + 2O2(g)
D. H2SO4(l)  2H(g) + S(s) + 4O(g)
E. H2(g) + S(s) + 2O2(g)  H2SO4(l)
9.
Which of the following electronic transitions in a hydrogen atom would have the longest
wavelength?
10.
A.
n = 4 to n = 1
B.
n = 4 to n = 2
C.
n = 2 to n = 1
D.
n = 4 to n = 3
E.
n = 3 to n = 1
Which of the following is associated with the quantum number ℓ?
A.
Orbital size
B.
Orbital orientation
C.
Orbital shape
D.
Orbital uncertainty
E.
Orbital organization
Page 4 of 17
CHEF 114, Trimester2 2009/2010
11.
12.
Which of the following elements has two unpaired electrons when it is a +3 ion?
A.
Vanadium
D.
Antimony
B.
Aluminum
E.
Selenium
C.
Cadmium
Which of the following elements would have the greatest difference between the first and
the second ionization energy?
13.
14.
15.
16.
A.
Calcium
D.
Potassium
B.
Arsenic
E.
Phosphorus
C.
Bromine
Which one of the following is most likely to be a covalent compound?
A.
Rb2O
B.
BaO
D.
SeO2
E.
MnO2
C.
SrO
What type of chemical bond holds the atoms together in a water molecule?
A.
Ionic bond
B.
Polar covalent bond
C.
Nonpolar covalent bond
D.
Coordinate covalent bond
E.
Dative covalent bond
Which of these molecules has a zero dipole moment?
A.
H2S
B.
NH3
D.
SO2
E.
H2O
C.
BF3
Which of the following correctly lists species in order of INCREASING size?
A.
O2 < O2+ < O2–
D.
O2+ < O2– < O2
B.
E.
O2– < O2+ < O2
O2+ < O2 < O2_
Page 5 of 17
C. O2– < O2 < O2+
CHEF 114, Trimester2 2009/2010
17.
Consider an electrochemical cell constructed from the following half cells, linked by a
KCl salt bridge.
• a Fe electrode in 1.0 M FeCl2 solution
• a Sn electrode in 1.0 M Sn(NO3 )2 solution
When the cell is running spontaneously, which statement below is TRUE?
18.
19.
20.
A.
The tin electrode loses mass and the tin electrode is the cathode.
B.
The tin electrode gains mass and the tin electrode is the cathode.
C.
The iron electrode gains mass and the iron electrode is the anode.
D.
The iron electrode loses mass and the iron electrode is the cathode.
E.
The iron electrode gains mass and the iron electrode is the cathode.
Which one of the following reagents is capable of transforming Fe3+(1 M) to Fe2+(1 M)?
A.
H2(1 atm)
B.
NO3 (1 M)
D.
Br (1 M)
E.
H+(1 M)
C.
O2(1 atm)
C.
C6H4Br2
Which of the following is an aromatic compound?
A.
C2H2
B.
C6H12
D.
C5H10
E.
C2H4Br2
Which type of organic compound does NOT contain a carbonyl group?
A.
ethers
B.
carboxylic acids
D.
aldehydes
E.
esters
Page 6 of 17
C.
ketones
CHEF 114, Trimester2 2009/2010
SECTION B
Answer ALL the questions in this section.
Show your working clearly.
Start your answer for each new question on a fresh sheet of paper.
(40 marks)
QUESTION 1 [10 marks]
(a)
Use the Born-Haber cycle to calculate the lattice energy of MgH2(s) given the following
data:
[6 marks]
ΔH(sublimation) Mg = 147.1 kJ/mol
I1 (Mg) = 737.7 kJ/mol
I2 (Mg) = 1450.7 kJ/mol
Bond energy (H–H) = 436.0 kJ/mol
H(g) + e-
H- = -72.8 kJ/mol
ΔH of [MgH2(s)] = –75.3 kJ/mol
(b)
Salts containing the fulminate ion, CNO-, are used in explosive detonators. Draw ALL
the possible Lewis structures of the fulminate ion, and use formal charge to predict which
is the most plausible structure.
(Hint: N is the central atom)
[4 marks]
Page 7 of 17
CHEF 114, Trimester2 2009/2010
QUESTION 2 [10 marks]
(a)
Complete the table below:
Compound
[5 marks]
Electron pairs around central atom
Total Bonding
Lone pair
Arrangement of
electron pairs
Molecular
shape
NF3
XeF4
(b)
For the molecule of PF5.
[2 + 1½ + ½ = 4 marks]
(i)
Draw the Lewis structure of PF5 and determine the hybridization of the central atom.
(ii)
What bond angles are predicted by VSEPR theory for the F –P –F bonds in PF5?
(iii)
According to the VSEPR theory, is the PF5 molecule polar or nonpolar?
QUESTION 3 [10 marks]
(a)
i)
Balance the following redox equation by the ion-electron method:
Cr2O72- + Fe2+
Cr3+ + Fe3+ (in acidic solution)
[3 marks]
ii)
The oxidation of 25.0 mL of a solution containing Fe2+ requires 26.0 mL of
0.0250M K2Cr2O7 in acidic solution. By using the balanced equation in question
(i) above, calculate the molar concentration of Fe2+.
[3 marks]
Page 8 of 17
CHEF 114, Trimester2 2009/2010
(b)
The cell potential measured for the electrochemical cell represented by the cell diagram
below is +0.70 V at 25 C. Calculate the concentration of hydrogen ions used in the cell.
Given:
Zn(s)|Zn2+(aq, 1M)||H+(aq, x M)|H2, 1atm|Pt(s)
E (Zn2+/Zn) = -0.76 V; E (H+/H2) = 0
[4 marks]
QUESTION 4 [10 marks]
(a)
Draw the structure of the following organic compounds:
i)
2,3,3-trimethylpentane
ii)
3-methyl-1-pentene
iii)
1-butanol
iv)
2-methyl-3-hexyne
v)
bromobenzene
Page 9 of 17
[5 marks]
CHEF 114, Trimester2 2009/2010
b)
Give the IUPAC name of the structures below:
[5 marks]
i)
O
CH2
C
H
ii)
H3C
O
CH2CH3
iii)
Cl
O
CH3
CH2
C
OH
CH3
CH2
C
O
iv)
CH2 CH3
O
v)
CH3CHCH2CH3
NH2
Page 10 of 17
CHEF 114, Trimester2 2009/2010
SECTION C
Answer any 4 out of 5 questions in this section.
Show your working clearly.
Start your answer for each new question on a fresh sheet of paper.
(40 marks)
QUESTION 1 [10 marks]
a)
The percent composition by mass of tartaric acid is: 32.01% C, 4.03% H, and 63.96% O.
(i) Determine the empirical formula of tartaric acid.
[2½ marks]
(ii) Given that the molecular mass of tartaric acid is 150 amu, determine its molecular
formula.
b)
[1½ marks]
Aqueous solutions of potassium sulphate and barium nitrate were mixed:
K2SO4(aq)
(i)
+ Ba(NO3)2(aq) → ? + ?
Complete and balance the molecular equation above. Include the physical states
(aq, s, ℓ, or g).
(ii)
(iii)
[2 marks]
Write the total ionic equation and net ionic equation. Include the physical states
(aq, s, ℓ, or g) and charges in the net ionic equation.
[3 marks]
Which species are the spectator ions?
[1 marks]
Page 11 of 17
CHEF 114, Trimester2 2009/2010
QUESTION 2 [10 marks]
a)
A sample of hydrogen gas was collected over water at 21C and 685 mmHg. The volume
of the container was 7.80 L. Calculate the mass in grams of H2(g) collected.
(Vapor pressure of water = 18.6 mmHg at 21C)
[4 marks]
b)
The bond enthalpy of the Br-Cl bond is equal to H for the reaction
BrCl(g)  Br(g) + Cl(g).
Use the following data to find the bond enthalpy of the Br-Cl bond.
Br2(l) → Br2(g)
Ho = 30.91 kJ/mol
Br2(g) → 2Br(g)
Ho = 192.9 kJ/mol
Cl2(g) → 2Cl(g)
Ho = 243.4 kJ/mol
Br2(l) + Cl2(g) → 2BrCl(g) Ho = 29.2 kJ/mol
[3 marks]
c)
Suppose 75 g of water at 25C is heated until it boils to dryness. Calculate the total
amount of heat in kJ used in the process?
Given: Heat of fusion of water, Hfusion = 335 J/g
Specific heat of water = 4.184 J/g·C
Heat of vaporization of water, Hvaporization = 2262 J/g
[3 marks]
Page 12 of 17
CHEF 114, Trimester2 2009/2010
QUESTION 3 [10 marks]
a)
One of the visible lines in the spectrum of hydrogen occurs at 486 nm. What is the
energy of a photon of this wavelength?
[2 marks]
b)
Is there any difference in the electron configuration between carbon-14 and carbon-12?
Why?
[2 marks]
c)
Compare the electron configurations of Mg2+ and F−. What can you conclude based on
their configurations?
[3 marks]
d)
Which has greater radius, a Cl− ion or a Cl atom? Briefly explain.
[3 marks]
QUESTION 4 [10 marks]
(a)
Arrange these compounds in order of decreasing lattice energy:
InAs, KBr, LiCl, SrSe, ZnS.
(b)
[2 marks]
Which of the following pair of elements has the greater bond strength?
C – H or Ge – H
Give your reason:
(c)
[2 marks]
Write the Lewis structure of N2H2 and indicate the number of sigma bonds and pi bonds
in N2H2.
(d)
(i)
[2 marks]
Use orbital diagrams to explain the hybridization on the central atoms in the
following NH3 molecules.
(ii)
Describe the bonding scheme in NH3
[4 marks]
Page 13 of 17
CHEF 114, Trimester2 2009/2010
QUESTION 5
(a)
Draw 5 structural isomers for the C6H14 molecule. Name them according to the IUPAC
system.
[5 marks]
(b)
An acidified solution was electrolyzed using copper electrodes. A constant current of
1.18 ampere caused the anode to lose 0.584 g after 1.52 x 103 s.
i)
What is the gas produced at the cathode?
[1 mark]
ii)
Write the half-reactions at the electrodes.
[2 marks]
iii)
Calculate the volume at STP of the gas.
[2 marks]
-END OF QUESTION PAPER-
Page 14 of 17
CHEF 114, Trimester2 2009/2010
PERIODIC TABLE
VIIIA
(18)
1A
1
H
IIA
(2)
IIIA
(13)
IVA
(14)
VA
(15)
VIA
(16)
1.008
2
VIIA
(17)
He
4.003
3
4
5
6
7
8
9
10
Li
Be
B
C
N
O
F
Ne
6.941
11
9.012
12
10.81
13
12.01
14
14.01
15
16.00
16
19.00
17
20.18
18
IIIB
(3)
IVB
(4)
VB
(5)
VIB
(6)
VIIB
(7)
VIIIB
(9)
IB
(11)
1IB
(12)
Na
Mg
22.99
19
24.31
20
21
22
23
24
25
26
27
28
29
30
K
Ca
Sc
Ti
V
Cr
Mn
Fe
Co
Ni
Cu
Zn
Ga
Ge
As
Se
Br
Kr
39.10
37
40.08
38
44.96
39
47.90
40
50.94
41
52.00
42
54.94
43
55.85
44
58.93
45
58.70
46
63.55
47
65.39
48
69.72
49
72.61
50
74.92
51
78.96
52
79.90
53
83.80
54
(8)
(10)
Al
Si
P
S
Cl
Ar
26.98
31
28.09
32
30.97
33
32.06
34
35.45
35
39.95
36
Rb
Sr
Y
Zr
Nb
Mo
Tc
Ru
Rh
Pd
Ag
Cd
In
Sn
Sb
Te
I
Xe
85.47
55
87.62
56
88.91
57
91.22
72.
92.91
73
95.94
74
98
75
101.1
76
102.9
77
106.4
78
107.9
79
112.4
80
114.8
81
118.7
82
121.8
83
127.6
84
126.9
85
131.3
86
Cs
Ba
La
Hf
Ta
W
Re
Os
Ir
Pt
Au
Hg
Tl
Pb
Bi
Po
At
Rn
132.9
87
137.3.
88
138.9
89
178.5
104
180.9
105
183.9
106
186.2
107
190.2
108
192.2
109
195.1
110
197.0
200.6
204.4
207.2
209.0
(209)
(210)
(222)
Fr
Ra
Ac
Rf
Db
Sg
Bh
Hs
Mt
Ds
(223)
(226)
(227)
(261)
(262)
(266)
(264)
(269)
(268)
(269)
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
140.1
90
140.9
91
144.2
92
(145)
93
150.4
94
152.0
95
157.3
96
158.9
97
162.5
98
164.9
99
167.3
100
168.9
101
173.0
102
175.0
103
Th
Pa
U
Np
Pu
Am Cm
Bk
Cf
Es
Fm
Md
No
Lr
232.0
(231)
238.0
(237)
(244)
(243)
(247)
(251)
(252)
(257)
(258)
(259)
(260)
(247)
TABLE OF CONSTANTS
Avogadro's number = 6.022 x 10 23 /mol
Gas constant, R = 0.0821 L.atm/ K.mol
1 atm = 760 mmHg = 760 torr = 101,325 Pa
Gas constant, R = 8.314 J/ K.mol
1 J = 1 kg. m2 / s2
1 L.atm = 101.3 J
Specific heat of water = 4.184 J/g.C
Speed of light, c = 3.00 x 108 m/s
RT/F = 0.0257 V at 25 C
1 Faraday = 96500 Coulomb
Planck constant, h = 6.63 x 10-34 J.s
Rydberg constant, RH = 2.18 x 10-18 J
Page 15 of 17
CHEF 114, Trimester2 2009/2010
Standard Reduction Potentials
Eo (V)
Half-Reaction
Au3+(aq) + 3e-
Au(s)
1.42
Cl2(g) + 2e-
2Cl-(aq)
1.358
O2(g) + 4H+(aq) + 4eBr2(g) + 2e-
2H2O
1.23
2Br-(aq)
NO3- (aq) + 4H+ + 3e-
1.085
NO(g) + 2H2O
0.96
Fe3+(aq) + e-
Fe2+(aq)
0.771
Cu2+(aq) + 2e-
Cu(s)
0.34
2H+(aq) + 2e-
H2(g)
0.00
Sn2+(aq) + 2e-
Sn(s)
-0.14
Pb2+(aq) + 2e-
Pb(s)
-0.22
Ni2+(aq) + 2e-
Ni(s)
-0.23
Cd2+(aq) + 2e-
Cd(s)
-0.40
Fe2+(aq) + e-
Fe(s)
-0.41
Zn2+(aq) + 2e-
Zn(s)
-0.76
2H2O(l) + 2e-
H2(g) + 2OH-(aq)
-0.828
Mn2+(aq) + 2e-
Mn(s)
-1.18
Al3+(aq) + 3e-
Al(s)
-1.66
Mg2+(aq) + 2e-
Mg(s)
-2.375
Ca2+(aq) + 2e-
Ca(s)
-2.76
K+(aq) + e-
K(s)
-2.925
Page 16 of 17
CHEF 114, Trimester2 2009/2010
Name : __________________________
Student ID : ___________________
Section : _________________________
Lecturer : _____________________
Answer Sheet for Multiple Choice Questions (Section A).
Please use 2B pencil to fill the circle completely.
B
Example :
D
1.
A
B
C
D
E
11.
A
B
C
D
E
2.
A
B
C
D
E
12.
A
B
C
D
E
3.
A
B
C
D
E
13.
A
B
C
D
E
4.
A
B
C
D
E
14.
A
B
C
D
E
5.
A
B
C
D
E
15.
A
B
C
D
E
6.
A
B
C
D
E
16.
A
B
C
D
E
7.
A
B
C
D
E
17.
A
B
C
D
E
8.
A
B
C
D
E
18.
A
B
C
D
E
9.
A
B
C
D
E
19.
A
B
C
D
E
10.
A
B
C
D
E
20.
A
B
C
D
E
Page 17 of 17
E