Comparative Study Of Transition Elements Question Paper

Comparative Study Of Transition Elements

Course:Bachelor Of Science

Institution: Kenyatta University question papers

Exam Year:2009

KENYATTA UNIVERSITY
UNIVERSITY EXAMINATIONS 2008/2009
INSTITUTE OF OPEN LEARNING

EXAMINATION FOR THE DEGREE OF BACHELOR OF SCIENCE

SCH 400:
COMPARATIVE STUDY OF TRANSITION ELEMENTS
=================================================================
DATE: THURSDAY 13TH AUGUST 2009 TIME: 8.00 A.M. – 10.00 A.M.

INSTRUCTIONS
Attempt ALL Questions.

1.
Account for the following observations in the properties of transition metal elements

a)
The highest oxidation state for the early transition metal elements Sc, Ti, V,

Cr, and Mn is the group number. On the other hand the highest oxidation
state
for
the
later
elements of the same period (Fe, Co, Ni, and Cu) is less than
the
group
number.
(5
marks)
b)
When
AgNo3 solution is added to a solution of CrCl3 all the Cl- ions are

precipitated as AgCl, while only a third of the chlorides are precipitated
when
the
AgNO3 solution is added to a solution of WCl3 in water.

(5 marks)

c)
The Lewis acidity of the pentahalides MX5 (M = V, Nb, Ta) decreases in the
order
MF5 > MCl5 > MBr5 > Ml5.

(3 marks)

d)
The physical and chemical properties of Zr are similar to those of Hf but
differ
significantly
from
those
of
Ti.
(5
marks)

e)
Chromium is able to form CrO2Cl2 but not CrCl6 and yet both contain Cr+6.

(3 marks)
Page 1 of 3

f)
Tungsten can form WBr6 but chromium only forms CrBr4 even though they
are
in
the
same
group.
(3
marks)

g)
K2Cr2O7 is preferred to KMnO4 as a primary standard in volumetric analysis.

(3 marks)

Total = 27 marks

2.
i)
Draw the structure of each of the following species

a)
Cr
2-
2O7

b)
VF5

c)
TaCl5

(6 marks)

ii)
Write a balanced net ionic equation for each of the following reactions.

a)
A solution of Na2Cr2O7 turns from orange to yellow on addition of an
alkali
to
it.

b)
Both
acidic
and
alkaline
MnO -
4 solutions are decolorized by
potassium
iodide
solutions.
(6
marks)

Total 12 marks

3.
State and explain the general variation trend of each of the following properties

across the first transition series of the Periodic Table.
a)
Density
b)
Ionization
energy
c)
Polarizing
power
of
ions
(6
marks)

Total = 14 marks

Page 2 of 3
4.
a)
Gandhi found a black material in a rock on their farm and suspected it to
contain
MnO2. Briefly describe an experiment that he can carry out at the
Kenyatta
University
Inorganic
chemistry laboratories to confirm that the

material contains manganese. Illustrate the possible reactions with balanced

equations.

(7 marks)

b)
Describe the sulphate process for the manufacture of pigment grade TiO2.
Explain
why
TiO2 has replaced white lead as a paint pigment base.

(10 marks)

Total = 17 marks
Page 3 of 3

📘 Access 10,000+ CBC Exams With Marking Schemes

Comparative Study Of Transition Elements Question Paper

More Question Papers

Exams With Marking Schemes

End Term 3 Exams

Mid Term Exams

End Term 1 Exams

Opener Exams

Full Set Exams