Inorganic Chemistry Laboratory (CHMS3206)

BSc, Chemistry - CHMS

Semester: Second Semester

Level: 300

Year: 2017

Answers (200 )
REPUBLIC OF CAMEROON REPUBLIQUE DU CAMEROUN
Peace-Work-Fatherland Paix-Travail-Parie
THE UNIVERSITY OF BAMENDA UNIVERSITE DE BAMENDA
P.0 Box: 39 Bambili
Faculty
of Science Department of chemistry Lecturer: Anagho/Kono
Course code: CHMS3206
(Date: 05/08/2017
Course title: Inorganic Chemistry Laboratory
Date: 05/08/2017 Hall: Asanji Time: 1100-13.00 (2Hours)
1) The practical of year two chemistry is concerned with qualitative and quantitative analyses.
(i) What is the difference between these two types of analyses? (2marks)
(ii) Give the general principle of each of these analyses. (2marks)
(iii) Give one example of each of these analyses. (2marks)
2)
During a practical session, a student of Chemistry Year 2 prepared an aqueous solution of zinc sulfate and an
aqueous solution of nickel chloride but forgot to label them.
(i) Just by observing the two solutions, how would you identify each of them? Justify your answer.
(2marks)
(ii) How would you confirm them using chemical reagents? Write ail the observations and chemical equations.
(8marks)
(iii) State the steps you will use to determine the concentration of zinc ions in the aqueous solution of zinc sulfate.
(5marks)
(iv) State the steps you will use to determine the mass of chlorite ions in the aqueous solution of nickel chloride.
Give the name of the technique that you have described. (5marks)
3) Complete the following table! (5 marks)
Chemical species
(Na
+
,Cl )
-
[Ni(H
2
0)
6
]
+
[Ag(NH
3
)
2
]
+
FeSCN
2 +
u(
N
H
3
)
4
]
2+
Colour
Chemical species
AgCl
( S )
PbCr O
4
KI
[.C
U
(H
2
0)
6
]
2+
NaCl
( S )
Colour
4)
Consider the following ligands : Cl; Br; NH
3
and H
2
0
(i) Define crystal field stabilisation energy (CFSE) and spectroscopic series. (2 marks)
(ii) Arrange these ligands in increasing order of their ability to split the two sets of d orbitals of a given metal ion.
Justify your arrangement. (2 marks)
(iii) Give the mathematical relation between the wave length at the maximum absorbance and the CFSE of a
given complex. Define all the parameters of this equation and give their units in the international system of unit.
(5 marks)
Arrange in increasing order, the wave length of the complexes formed with each of the ligands at the maximum
absorbance. (2 marks)
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2
5)
Consider the following cations: Fe
3 +
; Mg
2 +
; Cu
2 +
; Pb
2 +
.
(i) Based on their solubility, give the name of the group to which these cations belong and the corresponding
reagents of the groups. (4 marks)
(ii) How will you separate a mixture of these four cations? Write all observations and the chemical equations.
(5 marks)
6-a) Compare double salts and complex salts (or complex compounds) based on the following parameters:
(i) Stability in water and in solid state; (2 marks)
(ii) Chemical bonds; (1 marks)
(iii) Isomerism; (1 marks)
(iv) Oxidation state of the metal ion; (1 marks)
6-b) Consider the following chemical species: (NH
4
)
2
Fe(S0
4
)
2
. 6H
2
0 and [Ni(NH
3
)
6
] Br
2
.
(i) Name these chemical species. (2marks)
(ii) Write the balanced chemical equation of the preparation of each of these chemical species (2marks)
(iii) List the chemical species present in the aqueous solution obtained by the dissolution of each of these
compounds in water. (2 marks)
(iv) How will you confirm the presence of each chemical species in the solutions in 6-b (ii) above? (5 marks)
(v) (NH
4
)
2
Fe(S0
4
)
2
. 6H
2
0 is prepared by two groups of students during practical. The first group obtained a
percentage yield of 88% and the second group a percentage yield of 110%. Give four raisons which can explain
the result obtained by each group. (4 marks)
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