Download Midterm 2

1. [7 points] Which of the following molecules will not have a geometric
isomer?
(a)
(b)
(c)
(d)
2. [7 points] When an ethylenediamine ligand coordinates to a metal cation,
which atoms in the ligand make bonds to the metal?
a.
b.
c.
d.
e.
2 oxygen atoms
2 nitrogen atoms
3 nitrogen atoms
2 carbon atoms
1 nitrogen atom and 1 oxygen atom
3. [7 points] Which of the following complexes will be diamagnetic?
a.
b.
c.
d.
e.
High spin octahedral [Fe(H2O)6]2+
Tetrahedral [MnCl4]1–
Low spin square planar [PdCl4]2–
Low spin octahedral [RhCl6]3–
Both (c) and (d) are examples of diamagnetic complexes
4. [7 points] Consider the following three molecular orbitals from the linear
BeH2 molecule?
H–Be–H
H–Be–H
H–Be–H
MO #1
MO #2
MO #3
Which of these molecular orbitals will have the highest energy?
(a) MO #1
(b) MO #2
(c) MO #3
(d) MO #1 and MO #2 will have the same energy (higher than MO #3)
5. [7 points] Which of the following complexes will have the smallest crystal
field splitting energy, Δ.
a.
b.
c.
d.
e.
Tetrahedral [CrCl4]1–
Octahedral [Cr(H2O)6]3+
Octahedral [CrCl6]3–
Octahedral [Cr(NH3)6]3+
Octahedral [Cr(en)3]3+
6. [7 points] What is the correct name for the compound [Rh(NH3)4Cl2]Cl
a.
b.
c.
d.
e.
Rhodium(III) tetraamminedichloro chloride
Tetraammoniadichlororhodium(III) chloride
Tetraaminedichlororhodium(III) chloride
Tetraaminetrichlororhodium(III)
Dichlorotetraaminerhodium(III) chloride
7. [7 points] Which of the following equations represents the reaction that can
be used to prepare nickel(II) vanadate by solid state reaction?
a.
b.
c.
d.
e.
Ni (s) + VO4 (s) → NiVO4 (s)
2NiO (s) + 2VO4 (s) → 2NiVO4 (s) + O2 (g)
4NiO (s) + 2V2O5 (s) + O2 (g) → 4NiVO4 (s)
3NiO (s) + V2O5 (s) → Ni3(VO4)2 (s)
6NiO (s) + 4VO4 (s) → 2Ni3(VO4)2 (s) + 3O2 (g)
8. [7 points] The crystal field splitting for the complex ion, [V(H2O)6]4+ is 2.00
eV. What color would you expect a solution of this complex ion to be (there
is only one peak in the absorption spectrum)?
a.
b.
c.
d.
e.
green
red
colorless
blue
orange
9. [7 points] CdSe is a semiconductor with a band gap of 1.7 eV. What is the
color of CdSe?
a.
b.
c.
d.
e.
White
Black
Yellow
Orange
Green
10. [7 points] The ions MnO4–, TcO4– and MoO42– are isoelectronic. Arrange
these ions in order of increasing charge transfer energy (CT1).
a.
b.
c.
d.
e.
[Smallest
[Smallest
[Smallest
[Smallest
[Smallest
CT1]
CT1]
CT1]
CT1]
CT1]
MoO42– < TcO4– < MnO4– [Largest CT1]
TcO4– < MoO42– < MnO4– [Largest CT1]
MnO4– < TcO4– < MoO42– [Largest CT1]
TcO4– < MnO4– < MoO42– [Largest CT1]
MnO4– < MoO42– < TcO4– [Largest CT1]
11. [7 points] Consider the following reaction:
Ni(en)3 (aq) + 6NH3 (aq) ↔ Ni(NH3)62+ (aq) + 3 en
Does the equlibrium favor the reactants or products, and why ?
a.
b.
c.
d.
The
The
The
The
equilibrium
equilibrium
equilibrium
equilibrium
favors
favors
favors
favors
the
the
the
the
reactants, because of ΔSrxn
products, because of ΔSrxn
reactants, because of ΔHrxn
products, because of ΔHrxn
12. [7 points] Which of the following compounds will have the smallest band
gap?
a.
b.
c.
d.
e.
SrCrO4
SrMoO4
PbCrO4
SrCrO4
BaCrO4
13. [7 points] Which of the following ligands is not a polydentate ligand?
a.
b.
c.
d.
e.
Oxalate (C2O4)2–
EDTA4–
Bipyridine (bipy)
Cyanide (CN–)
All of the above ligands are polydentate ligands
14. [7 points] How much calcium carbonate is needed to make 5.00 g of CaWO4
from the reaction between calcium carbonate and tungsten (VI) oxide?
a.
b.
c.
d.
e.
1.74 g
0.97 g
2.15 g
2.51 g
None of the above
15. [7 points] Consider the phase diagram for NiWO4 (which has a monoclinic
crystal structure) to CuWO4 (which has a triclinic crystal structure) shown
below.
1600
Temperature (°C)
Liquid
1200
Eutectic Point
800
400
0
0.25
0
Pure
NiWO4
0.50
x
Ni1-xCuxWO4
0.75
1.00
Pure
CuWO4
If we prepare a sample with an overall composition of Ni0.9Cu0.1WO4 at 400
°C (denoted by the
symbol), what can we say about the sample?
a.
b.
c.
d.
e.
The
The
The
The
The
sample
sample
sample
sample
sample
will be a homogeneous mixture of triclinic crystals
will be a homogeneous mixture of monoclinic crystals
will be a two-phase mixture of monoclinic & triclinic crystals
will be a two-phase mixture of monoclinic crystals
will be a two-phase mixture of triclinic crystals
16. [7 points] Isomers which are mirror images of each other are called _____.
a.
b.
c.
d.
e.
Geometric isomers
Coordination-sphere isomers
Optical isomers
Linkage isomers
Structural isomers
The next three problems (18-20) deal with an aqueous solution containing the
complex ion [Mn(H2O)6]3+. The optical absorption spectrum taken on this solution is
shown below (the peak falls at a wavelength of ~ 450 nm).
0.8
0.7
Absorbance
0.6
0.5
0.4
0.3
0.2
0.1
0
400
500
600
700
Wavelength (nm)
17. [7 points] The manganese in this complex has a high spin configuration. How
many unpaired electrons are there per Mn atom?
a.
b.
c.
d.
e.
0
2
3
4
5
18. [7 points] What is the crystal field splitting, Δ, for the d-orbitals on
manganese?
a.
b.
c.
d.
e.
Δ
Δ
Δ
Δ
Δ
=
=
=
=
=
4.4 eV
2.2 eV
3.6 eV
1.7 eV
2.8 eV
19. [7 points] What is the color of this solution?
(a) Blue
(b) Orange
(c) Violet
(d) Green
(e) Colorless
20. [7 points] Based on entropy considerations alone, which of the following
equations would you expect to have the largest equilibrium constant
(equilibrium lies farthest to the right)?
Reaction 1:
[Cu(NH3)4]2+ + 4 CN- → [Cu(CN)4]2- + 4NH3
Reaction 2:
[Ni(NH3)6]2+ + 3 en → [Ni(en)3]2+ + 6NH3
Reaction 3:
[Cu(NH3)4]2+ + 6 H2O → [Cu(H2O)6]2+ + 4NH3
a.
b.
c.
d.
Reaction 1
Reaction 2
Reaction 3
Not enough information is given to know
21. [7 points] What is the shape of a molecule of white phosphorous, P4?
a.
b.
c.
d.
e.
square
a pyramid (with triangular faces)
linear
T-shaped
bent
22. [7 points] Which of the following oxides would produce a basic solution:
Na2O, MgO, CO2, SO3, P4O10?
a.
b.
c.
d.
e.
Na2O
MgO
Na2O & MgO
SO3 & P4O10
CO2, SO3 & P4O10
23. [7 points] Which of the following molecules will have the shortest O-O
bonds?
a.
b.
c.
d.
e.
O2
O3
H2O2
O2–
The O-O bonds will the same length (and shorter than the other
compounds) in (a) O2 and (b) O3
24. [7 points] Which of the following substances is a semiconductor?
a.
b.
c.
d.
e.
In
Ge
Pb
PCl5
None of the above substances are semiconductors
25. [7 points] In the crystal structure of elemental arsenic how many bonds do
you expect each As atom to make with neighboring As atoms?
a.
b.
c.
d.
e.
1
2
3
4
5
Approximate Wavelengths of the Visible Spectrum
Violet
Blue
Green
Yellow
Orange
Red
400-425 nm
425-492 nm
492-575 nm
575-585 nm
585-647 nm
647-700 nm
Spectrochemical Series
Weak Field
Ligands
Cl– < F– < H2O < NH3 < en < NO2– < CN–
Physical Constants & Conversion Factors
h = 6.626 × 10-34 J-s
c = 2.998 × 108 m/s
R = 8.314 J/K-mol
1 Å = 10 pm = 1 × 10-10 m
1 eV = 1.602 × 10-19 J
1 F = 96,500 C/mol = 96,500 J/V-mol
1 A = 1 C/s
1 eV = 1.602 × 10-19 J
Strong Field
Ligands