Prelims Inorganic Chemistry
St Anne’s and Oriel Colleges
HT 2017
Non-metal chemistry
Suggested reading:
• Basic Inorganic Chemistry, Cotton, Wilkinson & Gaus
• Introduction to Modern Inorganic Chemistry, MacKay, MacKay & Henderson
• Main Group Elements, Massey
• Chemistry of the Elements, Greenwood & Earnshaw
Questions:
(i) For elements of the p-block, bond strengths tend to decrease with increasing principal quantum
number, whereas the inverse is true for transition metals and their compounds. Why?
(ii) Review the oxides of the following elements:
Cs
B
C
N
O
P
S
Cl
I
Se
Xe
(iii) Describe the bonding in and structures of the following species (some may be polymorphic):
CaC2
Li4 Me4
CsO2
NO
B3 N 3 H 6
BN
Li3 N
Be4 O(OAc)6
(iv) Compare and contrast the chemistries of the following pairs of elements:
N and P
O and S
F and Cl
In each case, begin your answer by explaining what you think the key similarities and differences
are. Follow with more specific arguments, perhaps taking in turn the strengths of bonds they
form (σ vs π), available oxidation states, interesting compounds, and so on. Wherever possible
relate your points back to the general considerations outlined first, and make sure to support
your arguments with plenty of examples.
(v) Discuss the trends evident in the following data for homopolar multiple bond energies (kJ mol−1 ):
C=C
C≡C
602
835
N=N
N≡N
P≡P
As≡As
Sb≡Sb
Bi≡Bi
418
942
481
380
295
192
O=O
494
S=S
Se=Se
Te=Te
425
272
218
Prelims Inorganic Chemistry
St Anne’s and Oriel Colleges
HT 2017
(vi) Balance the following reaction equation occurring in aqueous solution:
NaNO2 + NaI + H2 SO4 → I2 + NaHSO4 + NO
(vii) Consider the reaction scheme below and then answer all the following questions and provide
information to support your identification. Note that reagents and products do not necessarily
specify the stoichiometry of each reaction.
(a) Identify compounds A–I and write balanced equations for the reactions taking place.
(b) Comment on the difference in the reactions of A and F with water.
Prelims Inorganic Chemistry
St Anne’s and Oriel Colleges
HT 2017
Past paper questions:
(2014 Prelims Resit)
7.
Examine the following reaction scheme and then answer all of the questions
given below.
NO
O2
A
Cl2
AlCl3
J
H2 O
C
NH3
B
J
NH3
E
∆
G
+ H2O
A
B
C
D
E
F
G
H
I
D
+
F
∆
NaNH2
Η
+ Η2 Ο
Ι + NaOH + NH3
Brown paramagnetic gas with RMM 46.0.
Diamagnetic gas with RMM 92.0.
Weak acid with pKa = 3.35.
Strong acid, pKa = −1.3. Reacts with Cu to give NO and other products.
Crystalline solid.
Crystalline solid.
Colourless diamagnetic gas with RMM 28.0.
Colourless diamagnetic gas with RMM 44.0.
Crystalline solid soluble in water. Addition of a solution of I to Pb(NO3)2
solution gives a precipitate that is a shock-sensitive explosive.
Solid giving conducting solution in CH3CN.
[RAMs N=14.0 O=16.0]
(a) Identify the compounds A-J and write balanced equations for the reactions
taking place.
[14]
(b) Construct a molecular orbital diagram for NO and use this to account for the
formation of J in the reaction scheme given above.
[3]
(c) Describe the bonding in A and H and account for the differences in
shape of the two molecules.
[3]
(d) Write a balanced equation for the reaction which occurs between the
acid D and Cu to generate NO.
[3]
(e) Describe one other method for the preparation of NO.
[2]
Turn over
CCHE 4271
5