DEPARTMENT OF CHEMISTRY, CFS, IIUM
SEMESTER I, 2013/2014
QUIZ 5
SHE 1315
NAME:……………………………………………MATRICNO………………GROUP:…………
Answer all questions.
[30 mins]
PART I [5 marks]
1
1
1
Which of these substances is an ionic compound?
A
CO
B
SrF2
C
Cl2O
D
HCl
B/L1/6a
Which of the following pairs of atoms are unlikely to form an ionic compound?
A
Ni, O
B
Na, F
C
Cu, Cl
D
Li, Mg
D/L1/6a
Which of the following pairs of atoms are unlikely to form an ionic compound?
A
Ni, O
B
Na, Ba
C
Cu, Mg
D
Li, Mg
A/L1/6a
2
How many σ bonds in the molecule above?
A
1
B
2
C
12
D
13
C/L1/6n
2
How many ∏ bonds in the molecule above?
2
3
A
1
B
2
C
12
D
13
B/L1/6n
How many pi bonds are there in this molecule?
A
5
B
10
C
17
D
18
A/L1/6n
Which of the following compound is a polar molecule?
A
XeF2
B
BF3
C
CCl4
D
NH3
D/L2/6k
3
3
Which of the following has a zero dipole moment?
A
SO2
B
NO2
C
CS2
D
OF2
C/L2/6k
Which of the following compound is a polar molecule?
A
CO2
B
SeCl6
C
OBr2
D
GeH4
C/L2/6k
4
4
4
5
5
5
What is the hybridization of I in ICl4-?
A
sp
B
sp3
C
sp3d
D
sp3d2
D/L2/6m
What is the hybridization of As in AsF6-?
A
sp
B
sp3
C
sp3d
D
sp3d2
D/L2/6m
Which of the following compounds contains sp2 hybrid orbitals?
A
CH4
B
BF3
C
H2O
D
BeF2
B/L2/6m
Which of the following species has a bond angle of 120°?
A
H2O
B
PH3
C
AlBr3
D
CO2
C/L3/6i
By using VSEPR theory, what is the bond angle of BF 2-?
A
90°
B
< 120°
C
180°
D
< 109.5°
B/L3/6i
By using VSEPR theory, what is the bond angle of NF3?
A
Slightly less than 90°
B
Slightly less than 109.5°
C
Slightly less than 120°
D
Slightly less than 180°
B/L3/6i
PART II [10 marks]
(SET A)
1
By using Lewis structure, show the formation of dative covalent bonding for NH4+.
[2]/L2/6(c)
+
H
H
H
+
N:
H
H
H
H+
N
[1]
2
H
[1]
Formic acid secreted by certain species of ant.
:O: 1
(a)
(b)
C
:O:
H
H
2
Calculate the formal charge for O1.
Formal charge O1: 6 – (½ 4 + 4) = 0
[1]/L1/6(f)
Arrange C-H; C-O2; O-H in the order of increasing bond length. [1]/L1/6(d)
O-H < C-H < C-O2
3
(a)
Phosphorous acid as shown below is the compound described by the formula
H3PO3. Phosphorous acid is an intermediate in the preparation of other
phosphorus compounds.
H
H
..
..O
P
..
..O
H
:O:
State the exception of octet rule posses by P.
[1]/L1/6(g)
Expanded octet.
(b)
Show an arrow in the molecule above to indicate the direction of dipole moment
between P
H.
Answer in the diagram above
[1]/L1/6(e)
4
Carbon disulfide is a colorless volatile liquid with the formula CS 2. The compound is used
frequently as a building block in organic chemistry as well as an industrial and chemical
non-polar solvent. There are three resonance structures for CS2, draw another two
resonance structures in the boxes below.
..
C
S
..
..S:
..
:S
..
[2]/L2/6(h)
..
C
..
..S
S
[1]
5
C
..
..S
[1]
Describe the hybridization process of C in molecule HCN.
Ground state C : [He]
__
__ __ __
2s
2p
Excited state C : [He]
__
[2]/ L3/6(l)
[1]
__ __ __
2s
2p
Hybrid state C : [He] __ __
__ __
sp
2p
[1]
(SET B)
1
By using Lewis structure, show the formation of dative covalent bonding for H3O+.
[2]/L2/6(c)
+
.. ..
O
H
+
H+
H
H
[1]
Formic acid secreted by certain species of ant.
:O: 1
C
:O:
H
H
H
[1]
2
..
O
H
2
(a)
Calculate the formal charge for O2.
Formal charge O2: 6 – (½ 4 + 4) = 0
3
[1]/L1/6(f)
(b)
Arrange C-H; C-O2; O-H in the order of decreasing bond length.[1]/L1/6(d)
C-O2 > C-H > O-H
(a)
Cryolite, Na3AlF6 (below) is an indispensable component in the electrochemical
manufacture of aluminium.
3-
..
..
: ..F
..
: ..F
: F:
..
..F:
..
..F :
Al
: F..:
State the exception octet rule posses by Al?
[1]/L1/6(g)
Expanded octet.
(b)
4
Show an arrow in the molecule above to indicate the direction of dipole moment
between Al
F.
Answer in the diagram above
[1]/L1/6(e)
Nitrous oxide, commonly known as laughing gas, is a chemical compound with the formula
N2O. It is an oxide of nitrogen. At room temperature, it is a colourless, non-flammable gas,
with a slightly sweet odour and taste. draw two resonance structures in the boxes below.
[2]/L2/6(h)
..
O
..
N
..
..N
[1]
5
..
..
:O
..
N
N
[1]
Describe the hybridization process of O in molecule H2O.
Ground state O : [He]
__ __ __ __
2s
2p
Excited state O : [He]
__
[2]/ L3/6(l)
[1]
__ __ __
2s
2p
Hybrid state O : [He] __ __ __ __
sp3
[1]