School of Chemistry
UNIVERSITY OF KWAZULU-NATAL, WESTVILLE CAMPUS
JUNE 2011 EXAMINATION
CHEM210: INORGANIC CHEMISTRY
DURATION: 3 HOURS
TOTAL MARKS: 100
Internal Examiner: Dr W E van Zyl
Moderating Board: Dr V O Nyamori
Dr I N Booysen
INSTRUCTIONS:
This paper consists of 15 pages and 5 questions.
A Periodic Table and Data Sheet are also supplied at the end of this paper.
Calculators may be used, but all work must be shown.
Use the overleaf pages should you run out of space, CLEARLY indicate if it needs to
be marked as well as the number of the question.
ANSWER ALL QUESTIONS DIRECTLY ON THE PAPER.
Students are requested, in their own interests, to write legibly.
STUDENT NUMBER:
SEAT NO:
Questions
1
2
3
4
5
TOTAL
Internal
Marks
External
Marks
SCHOOL OF CHEMISTRY, UNIVERSITY OF KWAZULU-NATAL, WESTVILLE CAMPUS
CHEM210 : INORGANIC CHEMISTRY
JUNE 2011 EXAMINATION
QUESTION 1
a. On a single graph, plot the radial distribution function, 4πr2R(r)2, versus
distance r from the nucleus, for the two atomic orbitals that are defined by
the following quantum numbers: n=2, l=0 and n=3, l=2. Label the plots.
(4)
b. Name the FOUR fundamental forces in Nature.
(2)
c. Fill an Aufbau diagram with the four valence electrons of carbon, and give
a set of quantum numbers (n, l, ml, ms) that uniquely defines each
electron within the respective orbitals.
(2)
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SCHOOL OF CHEMISTRY, UNIVERSITY OF KWAZULU-NATAL, WESTVILLE CAMPUS
CHEM210 : INORGANIC CHEMISTRY
JUNE 2011 EXAMINATION
QUESTION 1 (Cont.)
d. Write the electron configuration of the following chemical species. Use the
abbreviated noble gas format and list only the valence electrons.
I
P3Si4+
Br¯
Co3+
(5)
e. Draw each of the two orbitals dx2-y2 and dxy on a separate axes
system.
(2)
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SCHOOL OF CHEMISTRY, UNIVERSITY OF KWAZULU-NATAL, WESTVILLE CAMPUS
CHEM210 : INORGANIC CHEMISTRY
JUNE 2011 EXAMINATION
QUESTION 1 (Cont.)
f. Draw the Lewis-dot structure of the HPSe42- anion and assign a formal
charge to the P and all the Se atoms.
(3)
g. Use VSEPR theory to determine the name of the molecular
geometry/shape of each the following ions and molecule. State whether
the chemical species is polar or non-polar.
i) nitrate ion,
ii) triiodide ion,
iii) krypton tetrachloride.
(3)
[21]
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SCHOOL OF CHEMISTRY, UNIVERSITY OF KWAZULU-NATAL, WESTVILLE CAMPUS
CHEM210 : INORGANIC CHEMISTRY
JUNE 2011 EXAMINATION
QUESTION 2
a. Illustrate bonding in the H2S molecule in terms of Valence Bond
Theory. Your answer should indicate the filled atomic orbitals of S atom
in the ground-state, followed by 'promotion' showing the type of
hybridization that occurs among the appropriate orbitals.
(3)
b. Give the systematic IUPAC names for the following three coordination
complexes:
(3)
(i) (NH4)4 [CoCl2Br2(CN)2]
(ii) K2[Cu(dppm)(H2O)2]
(iii) [Au(NH3)2][Ag(CN)2]
c. Give the formula for the following three coordination complexes:
(3)
(i) lithium dicarbonylbis(oxalato)vanadate(II)
(ii) hexaamminechromium(II) carbonate
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SCHOOL OF CHEMISTRY, UNIVERSITY OF KWAZULU-NATAL, WESTVILLE CAMPUS
CHEM210 : INORGANIC CHEMISTRY
JUNE 2011 EXAMINATION
QUESTION 2 (Cont.)
(iii)
tris(acetylacetonate)iron(III)
d. Write the ionization isomer, as a formula, of [Pt(NH3)3(OH)]Br.
(1)
e.
Draw the
i) cis isomer of the complex [CrBr2(H2O)4], and the
ii) mer isomer of the complex [CrBr3(H2O)3]
(3)
[13]
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SCHOOL OF CHEMISTRY, UNIVERSITY OF KWAZULU-NATAL, WESTVILLE CAMPUS
CHEM210 : INORGANIC CHEMISTRY
JUNE 2011 EXAMINATION
QUESTION 3
a. Construct a molecular orbital (MO) energy diagram for the Cl2+ ion and
determine the bond order.
(4)
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SCHOOL OF CHEMISTRY, UNIVERSITY OF KWAZULU-NATAL, WESTVILLE CAMPUS
CHEM210 : INORGANIC CHEMISTRY
JUNE 2011 EXAMINATION
QUESTION 3 (Cont.)
b. Construct the molecular orbital (MO) energy diagram for the CO molecule,
and show the HOMO and LUMO orbitals. From this diagram determine the
bond order. Compare the C-O bond in both CO and CO2 and comment
which of these two species will have the longest bond length and
strongest relative bond strength.
(6)
c. List any four chemical species that are isoelectronic with selenide ion, Se2(2)
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SCHOOL OF CHEMISTRY, UNIVERSITY OF KWAZULU-NATAL, WESTVILLE CAMPUS
CHEM210 : INORGANIC CHEMISTRY
JUNE 2011 EXAMINATION
QUESTION 3 (Cont.)
d. Use the same barycentre to draw two crystal field splitting diagrams
showing how five degenerate d-orbitals of a transition-metal undergo a
change in energy when placed in an octahedral and a tetrahedral
crystal field environment. Show both ∆oct and ∆tetr on the drawing.
(4)
e. In crystal field theory, an octahedral complex within a d6 system can have
either configuration t2g6eg0 (low-spin) or t2g4eg2 (high-spin). Calculate the
Crystal Field Stabilization Energy (CFSE) for each system.
(3)
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SCHOOL OF CHEMISTRY, UNIVERSITY OF KWAZULU-NATAL, WESTVILLE CAMPUS
CHEM210 : INORGANIC CHEMISTRY
JUNE 2011 EXAMINATION
QUESTION 4
a. Draw and label the four unit cells each representing a different Bravais
lattice within the orthorhombic crystal system.
(4)
b.
Aluminum (Al) has a ccp arrangement of atoms as shown below.
The radius of Al is 1.432Å (143.2 pm). Calculate the lattice parameter, a,
of the unit cell and the density of solid Al (atomic weight = 26.98). Show
all work.
(4)
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SCHOOL OF CHEMISTRY, UNIVERSITY OF KWAZULU-NATAL, WESTVILLE CAMPUS
CHEM210 : INORGANIC CHEMISTRY
JUNE 2011 EXAMINATION
QUESTION 4 (Cont.)
c. NiO crystallises in the rock salt structure. Draw the structure and then
tabulate how many cations and anions there are, respectively, in the
body, face, edge and vertex (corners) of the unit cell and then sum them
to determine the total number of NiO formula units (Z) in the unit cell.
(4)
d. Use the Born-Mayer equation to estimate the lattice enthalpy of NaCl.
Data are provided, also consult attached Data Sheet: d (or ρ) = 34.5 pm;
do (or ro) = 282 pm; Madelung constant = 1.748.
(4)
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SCHOOL OF CHEMISTRY, UNIVERSITY OF KWAZULU-NATAL, WESTVILLE CAMPUS
CHEM210 : INORGANIC CHEMISTRY
JUNE 2011 EXAMINATION
QUESTION 4 (Cont.)
e. Use the data below to calculate the formation enthalpy, ∆Hf, for LiF(s)
by making use of a Born-Haber cycle. Show all reactions in the cycle.
∆H / (kJ/mol)
Sublimation of Li(s)
+161
Ionisation of Li(g)
+531
Dissociation of F2(g)
+158
Electron gain by F(g)
-328
Lattice enthalpy of LiF(s)
-1239
(5)
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SCHOOL OF CHEMISTRY, UNIVERSITY OF KWAZULU-NATAL, WESTVILLE CAMPUS
CHEM210 : INORGANIC CHEMISTRY
JUNE 2011 EXAMINATION
QUESTION 5
a. Make brief, accurate, and unique descriptive comment for EACH of the
following phosphorus oxides and -acids.
P4O6
(1 mark)
P4O10
(2 marks)
H3PO2
(1 mark)
H3PO3
(2 marks)
H3PO4
(2 marks)
(8)
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SCHOOL OF CHEMISTRY, UNIVERSITY OF KWAZULU-NATAL, WESTVILLE CAMPUS
CHEM210 : INORGANIC CHEMISTRY
JUNE 2011 EXAMINATION
QUESTION 5 (Cont.)
b.
Make two brief comments on each of the following key phrases and
trends regarding the Group 14 elements (C, Si, Ge, Sn, Pb).
i) catenation; ii) coordination numbers; iii) metallic character; iv) multiple
bonds
(2x4=8)
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SCHOOL OF CHEMISTRY, UNIVERSITY OF KWAZULU-NATAL, WESTVILLE CAMPUS
CHEM210 : INORGANIC CHEMISTRY
JUNE 2011 EXAMINATION
QUESTION 5 (Cont.)
c.
Make a brief, accurate, and unique descriptive comments for EACH of the
following Group 16 elements:
Oxygen
(2 marks)
Sulfur
(2 marks)
Selenium
(2 marks)
Tellurium
(2 marks)
Polonium
(2 marks)
(10)
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