Student Name:
CHEM 2218
Student ID:
Inorganic Chemistry I (Final Exam sample paper)
Part I: Multiple Choices (2 points each, 50 points in total)
1.
For a cube, the number of C6, C4, and C3 rotational axes is
(a) 1, 3, and 4, respectively (b) 0, 2, and 4, respectively (c) 0, 3, and 4, respectively
2.
The CO diatomic molecule contains infinite number of
(a) σv (b) i (c) σh (d) C2
3.
Identify the wrong lablel(s) in the following list used for representations of point
groups.
C1000, C10h, D100h, D2v, Ci, I, Oi, Td
4.
The Fe2(CO)9 molecule shown does not posses what element of symmetry?
(a) i
(b) σ
(c) S3
(d) C2
5.
A molecule having a point group of D4h contains all the symmetry
elements of a molecule having a point group of
(a) D4d
(b) D2d
(c) D3h
(d) none of the above
6.
How many mirror planes of symmetry are there in an icosahedron?
(a) 6
(b) 9
(c) 12
(d) 15
(e) 18
7.
Give the symmetry label for the molecular orbital associated with a trigonal
planar structure (you are given a character table for D3h).
(a) A1'
(b) A1"
(c) A2'
(d) A2"
8.
Identify the stronger acid?
H2Se vs. H2S
[Al(H2O)6]3+ vs. [Fe(H2O)6]3+
9.
Which one in the following is the least stable?
(a) [Al(H2O)6]3+
(b) [AlF6]3- (c) Mo(H2O)6
(d) Mo(CO)6
10.
Predict which way the following reactions will go (left or right)
(a) [AlF6]3+ + Ga(CN)6]3+ [GaF6]3+ + Al(CN)6]3+
(a) W(CO)5(PMe3) + NMe3 W(CO)5(NMe3) + PMe3
11.
Select the strongest base toward proton.
(a) NH3
(b) NHMe2 (c) PH3
12.
(d) PMe3
Which of the following reactions belong to the acid-base reactions?
(a) H + OH H2O.
(b) PF3 + F2 PF5.
(c) SiF4 + 2NaF Na2[SiF6].
(d) Mo + 6CO Mo(CO)6.
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13.
The concept of hard/soft acids and bases is useful in
(a) determining the strengths of Lewis bases.
(b) determining the strengths of Lewis acids.
(c) understanding the stabilities of salts.
(d) understanding the binding properties of Lewis acids/bases.
14.
Select the weakest Bronsted acid.
(a) H3PO4
(b) H2CO3
(c) H3BO3
(d) H2SeO4
15.
In the coordination compound (NEt4)2[Fe(en)(CN)4], where en = ethylenediamine
and Et = ethyl, the coordination number (C.N.) and oxidation number (O.N.) of
Fe, respectively are: (The atomic number of Fe is 26)
(a) C.N.=6; O.N.=4 (b) C.N.=6; O.N.=2 (c) C.N.=5; O.N.=2
(d) C.N.=5; O.N.=4 (e) C.N.=4; O.N.=3
16.
In [Cr(en)2Cl2]Br2, where en = ethylenediamine, how many 3d electrons does the
chromium ion have? The atomic number of Cr is 24.
(a)
3
(b) 4
(c) 5
(d) 6
(e) 2
17.
Which of the following complexes are chiral?
(a) cis-[Fe(en)2Br2]+ (b) Pt(en)ClBr (a square planar structure)
(c) Cr(NH3)4ClBr
(d) fac-Cr(NH3)3(Br)(Cl)(F)
O
C
O
C
CH2
O
CH2
O
N
CH2
Co
18.
Assign Λ or ∆ configuration for the complex shown on the right.
19.
Which of the following ligands can act as a bidentate ligand?
(a) NCS(b) SO42(c) CH3COO(d) CN-
CH2
NH
AcO
O
CH2
C
O
20.
Identify the correct statement. A mononuclear metal complex can be described as
an adduct of
(a) a Lewis acid and several Lewis bases.
(b) a Lewis base and several Lewis acids.
(b) several Lewis acids and bases
(c) None of the above.
21.
Which metal in the following would you expect to have the highest melting point?
(a) Na
(b) K
(c) Ca
(d) Cr
(e) Sc
22.
Which metal in the following would you expect to have the best conductivity?
(a) Zn
(b) Ti
(c) Cr
23.
Identify the stronger reducing agent.
(a) SnCl2 vs. PbCl2 (b) TlCl vs. InCl
24.
Which of the following are not monomeric.
(a) AlBr3
(b) SnO2
(c) BF3
(d) CO2
25.
Identify the more stable species.
(a) S2 vs. Se2
(b) Sn3H8 vs. Pb3H8
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Part II.
Medium and Long Questions
1.
Determine the point group for each of the following molecules.
(15 points)
(a) SF5Cl (S is the central atom)
(b) Al2Cl6 (edge-sharing bitetrahedra)
(c) SO2
(d) CH2FCl (e) stagerred conformation of ethane
2.
Please give the number for each of the following symmetry elements for BF3
(5 points)
i:
C3:
C2:
σ:
S3 :
(10 points)
3.
A metal complex, ML2X2E, adopts a square pyramidal structure.
Please (a) sketch all the possible geometric isomers.
(b) determine which one(s) is/are chiral.
4.
The difference between melting points (oC) is given below for each of the Group
IIB halides.
2+
Zn
Cd2+
Hg2+
F630
640
5
What deduction can you draw?
Cl405
390
25
Br355
300
80
I285
405
100
(5 points)
5.
AlF3 is insoluble in liquid HF, but dissolves if CsF is present. Briefly explain through
the use of chemical equation(s) and concepts of hard/soft acids/bases. (5 points)
6.
Consider the C-H σ bond stretching normal modes in benzene.
(10 points)
(a) How many such vibration modes does the molecule have?
(b) Please draw all the stretching normal modes.
(c) Give the symmetry labels to all the normal modes you draw in (b).
(d) Point out which are IR active and which are Raman active.
(You are given a character table for D6h)
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Answer Keys:
Part I. Multiple Choices
1. (c)
4. (a)
7. (c)
10. (a) left; (b) left
13. (c) and (d)
16. (e)
19. (b) and (c)
22. (a)
25. (a) S2; (b) Sn3H8
2. (a)
5. (b)
8. H2Se; [Al(H2O)6]3+
11. (b)
14. (c)
17. (a) and (d)
20. (a)
23. (a) SnCl2; (b) InCl
Part II.
Medium and Long Questions
1. (a) C4v
(b) D2h
(c) C2v
(d) Cs
3. D2v and Oi
6. (d)
9. (c)
12. (c) and (d)
15. (b)
18. ∆
21. (d)
24. (a) and (b)
(e) D3d
2. 1, 0, 3, 4 ,1
3. See No. 3 question in the 2nd assignment (answers to this question will be given in the
answer keys to the 2nd assignment)
4. The concept of soft/hard acids/bases can be used to explain the trend observed. Hard
acids prefer to bind hard bases. Exception can also be seen, indicating that the concept is
very qualitative.
FClBrILewis base hardness increases
Zn2+
Cd2+
Hg2+ Lewis acid hardness increases
5.
AlF3 + CsF
Cs+
+ [AlF4]-
or
AlF3 + 3 CsF 3 Cs+ + [AlF6]3-
This chemical equation explains the penomenon. HF cannot do the same because both H+
and F- are hard. They form stable species. Cs+ is softer than H+. Therefore, Cs+ and F- are
easier to be separated.
6. See No. 10 question in the 2nd assignment (answers to this question will be given in
the answer keys to the 2nd assignment)
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