BSc/MSci Course Unit Examination
29 April 2014 14:30 - 17:30
CHE203 Solid State and Inorganic Chemistry
Duration: 3 h
YOU ARE NOT PERMITTED TO START READING THIS QUESTION PAPER UNTIL INSTRUCTED TO
DO SO BY AN INVIGILATOR.
Answer all the questions in Section A and THREE questions from Section B. The total of marks available on
the paper is 120, with Section A worth 60 marks and Section B worth 60 marks.
A detailed marking scheme is provided for you guidance.
A data booklet is also provided, which may contain data and formulae relevant to the questions on this
examination paper.
A supplementary answer sheet is provided for question 2
CALCULATORS ARE PERMITTED IN THIS EXAMINATION. PLEASE STATE ON YOUR ANSWER
BOOK THE NAME AND TYPE OF MACHINE USED.
COMPLETE ALL ROUGH WORKINGS IN THE ANSWER BOOK AND CROSS THROUGH ANY WORK
WHICH IS NOT TO BE ASSESSED.
IMPORTANT NOTE: THE ACADEMIC REGULATIONS STATE THAT POSSESSION OF UNAUTHORISED
MATERIAL AT ANY TIME WHEN A STUDENT IS UNDER EXAMINATION CONDITIONS IS AN
ASSESSMENT OFFENCE AND CAN LEAD TO EXPULSION FROM THE COLLEGE. PLEASE CHECK
NOW TO ENSURE YOU DO NOT HAVE ANY NOTES IN YOUR POSSESSION. IF YOU HAVE ANY
THEN PLEASE RAISE YOUR HAND AND GIVE THEM TO AN INVIGILATOR IMMEDIATELY.
PLEASE BE AWARE THAT IF YOU ARE FOUND TO HAVE HIDDEN UNAUTHORISED MATERIAL
ELSEWHERE, INCLUDING TOILETS AND CLOAKROOMS IT WILL BE TREATED AS BEING FOUND IN
YOUR POSSESSION. UNAUTHORISED MATERIAL FOUND ON YOUR MOBILE PHONE OR OTHER
ELECTRONIC DEVICE WILL BE CONSIDERED THE SAME AS BEING IN POSSESSION OF PAPER
NOTES. MOBILE PHONES CAUSING A DISRUPTION IS ALSO AN ASSESSMENT OFFENCE.
EXAM PAPERS CANNOT BE REMOVED FROM THE EXAM ROOM.
Examiners: Dr I Abrahams, Dr TS Sheriff, Prof A Vlcek and Dr S Potts
© Queen Mary University of London, 2014
Page 2 of 5
CHE203(2014)
SECTION A
1.
Answer all parts.
(a) Using suitable sketches, explain the difference between p and n type semiconductors and
clearly indicate the position of the Fermi level in each case.
[4 marks]
(b) Using suitable sketches, describe the structure of ReO3 in terms of (i) close packing of ions
and (ii) polyhedral connectivity.
[4 marks]
(c) State one example of each of the following.
(i) A ccp structure with all tetrahedral sites full and octahedral sites empty.
(ii) An hcp structure with all tetrahedral sites empty and octahedral sites filled.
(iii) An hcp structure with all octahedral sites empty and half the tetrahedral sites filled.
[3 marks]
(d) A metal complex crystallised in space group P 1 and its structure was investigated using
X-ray single crystal diffraction. The highest peak in the Patterson vector density map was
found at u = 0.287, v = 0.135, w = 0.446 in the Patterson cell.
(i) Briefly explain why the Patterson method might be employed in solving this structure
rather than direct methods.
[1 mark]
(i) What are the likely coordinates (x, y, z) of the metal atom in the real unit cell?
[2 marks]
(e) Write balanced equations for the Haber process and the Ostwald process and explain their
importance.
[3 marks]
(f) Calculate the enthalpy (H) for the following reaction and comment on the significance of
the result obtained. [H (P–P) = 209 kJ mol–1; H (PP) = 490 kJ mol–1]
[4 marks]
P4 (g) → 2 P2 (g)
(g) Draw the structure of SF4 and predict the low temperature 19F (I = ½, 100%) NMR
spectrum for SF4.
[3 marks]
(h) Use Wade’s Rules to classify the following (car)borane species and state the formulae for
the parent closo structure where applicable.
[6 marks]
(i) [B11H17]
(ii) [CB10H15]–
(i) Explain why KMnO4 is intensely coloured (violet), whereas KTcO4 and KReO4 are
colourless.
[5 marks]
Question 1 continued overleaf
CHE203(2014)
Page 5 of 5
(j) Explain why the enthalpy of sublimation (atomization) of Re (s) is 704 kJ mol-1, whereas
that of Mn (s) is much lower at 221 kJ mol1.
[5 marks]
(k) Determine the metal oxidation state and d-electron configuration in the following
complexes (bpy = 2,2'-bipyridine):
(i) [Cu(phen)2]+
(ii) trans-[Rh(NH3)4Cl2]2+
(iii) [Mo2(-CH3COO)4]
(iv) [Mo(CN)8]3–
(v) [W(CO)6]
[5 marks]
(l) The equation below may be used to calculate magnetic moments for transition metal
complexes where there is an orbital angular momentum contribution in addition to the spin
contribution. Give one example of a first row transition metal complex in this category
and calculate its expected effective magnetic moment.
[3 marks]
μ eff  n(n  2 )  L(L  1 ) μ B
(m) Construct a molecular orbital energy diagram that represents the , , and  components of
the metal–metal bonding in homodinuclear transition metal complexes.
[6 marks]
(n) Use your diagram to deduce the , , and  configuration and likely bond order of
metal–metal bonds in the following compounds.
[6 marks]
Page 4 of 5
CHE203(2014)
SECTION B
2.
Bi2O3 exhibits two stable phases on heating (designated here LT and HT). Some
crystallographic parameters of these two polymorphs of Bi2O3 are given in the table below
which is reproduced as a separate sheet.
Parameter
Mr (g mol1)
Crystal system
a (Å)
b (Å)
c (Å)
 ()
 ()
 ()
Volume (Å3)
Z
Density g cm3
Space group
Space group (full)
LT-Bi2O3
465.96
Monoclinic
5.8496
8.1648
7.5101
112.98
HT-Bi2O3
465.96
5.6595
5.6595
5.6595
90
90
90
330.22
4
P21/c
P 1 21/c 1
8.540
Fm-3m
F 4/m -3 2/m
(a) Fill in the missing values in the table on the separate answer sheet and attach this to your
answer book.
[7 marks]
(b) Explain the meaning of each of the symbols that constitute the space group name P21/c.
[4 marks]
(c) Calculate the reciprocal lattice parameters a*, b*, c*, *, *, and * for LT-Bi2O3.
[5 marks]
(d) Make a sketch of the b* = 0 layer of the reciprocal lattice for LT-Bi2O3, clearly indicating
any systematic absences.
[4 marks]
3.
Answer all parts.
(a) Compare the structure and bonding of borazine and hexachloro(cyclo)phosphazene
(P3N3Cl6) with that of benzene.
[8 marks]
(b) Rationalise the bonding in diborane (B2H6) and predict the appearance of the 1H NMR
spectrum of B2H6. [1H, I = 1/2, 100%; 11B, I = 3/2, 80.1% abundant]
[7 marks]
(c) Name the following oxoacids of Group 17 and explain the trend in acid strength observed.
[5 marks]
HClO4 (pKa = –8) > HClO3 (pKa = –1) > HClO2 (pKa = 2) ~ H5IO6 (pKa = 2)
CHE203(2014)
4.
Page 5 of 5
Answer all parts.
(a) The mineral magnetite has a formula Fe3O4 and contains two FeIII and one FeII atoms per
structural formula. In the unit cell, there are two Fe atoms in octahedral sites and one Fe
atom in a tetrahedral site. Using LFSE arguments, decide whether the tetrahedral site is
occupied by FeII or FeIII.
[12 marks]
(b) The complexes [W(CO)5L] show an intense absorption band in the near-UV / visible
spectral region whose wavelength depends on L: 355 nm (pyridine), 347 nm
(3,4-di-methyl-pyridine), 440 nm (4-acetyl-pyridine), 455 nm (4-cyano-pyridine). Which
electronic transition is responsible for the absorption band? Explain your answer and the
ligand dependence.
[8 marks]
5.
Answer all parts.
(a) Deduce the lowest energy form of 2S+1LJ for the ions Ti3+, Cu2+, Co2+ and Mn2+. [8 marks]
(b) A simplified Tanabe-Sugano diagram for an octahedral d 3 ion is given below. What are the
term symbols labelled 1-6? Include subscript symmetry labels in your answers for 1-4.
[6 marks]
4
3
E/B
2
6
1
5
 /B
(c) What information is conveyed by the quantity B, known as the Racah parameter? Use the
data below to assess the relative covalency of the metal ligand bonding in the given
complexes. B = 1030 cm1 for Cr3+.
[6 marks]
Compound
[Cr(NH3)6]Br3
K3[Cr(CN)6]
B (cm–1)
650
530
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End of Paper