Get premium membership and access revision papers, questions with answers as well as video lessons.
Got a question or eager to learn? Discover limitless learning on WhatsApp now -
Start Now!
Comparative Study Of Transition Elements Question Paper
Comparative Study Of Transition Elements
Course:Bachelor Of Science
Institution: Kenyatta University question papers
Exam Year:
KENYATTA UNIVERSITY
UNIVERSITY EXAMINATIONS 2007/2008
SECOND SEMESTER EXAMINATION FOR THE DEGREE OF BACHELOR OF SCIENCE AND BACHELOR OF EDUCATION
SCH 400: COMPARATIVE STUDY OF TRANSITION ELEMENTS
DATE: MONDAY, 9TH JUNE 2008 TIME: 11.00 A.M. – 1.00 P.M.
___________________________________________________________________________
INSTRUCTIONS: Attempt ALL Questions.
1. Give possible reasons for the following observations:
(a) General, transition elements tend to have high electrical and thermal conductivities, tensile strength, density and melting points.
(4 marks)
(b) Most industrial catalysts are either transition metals, compounds
of transition metals or alloys of the metals. (2 marks)
(c) The third row of the d-block elements have only marginally larger
atomic radii than the second row elements. (3 marks)
(d) The third ionization potential of 26Fe is lower than that of 25Mn. (4 marks)
(e) Vanadium forms only the pentafluoride while Niobium and
Taut alum form all the pentahalides including the pentaiodide. (3 marks)
(f) Anhydrous halides MX3 of Sc, Y and La cannot be obtained by
drying the salts obtained from aqueous solutions.
2. (a) Draw the structures of the following species
(i) VF5
(ii) NbF5
(iii) TaCl4
(iv) Cr2O72-
(6 marks)
2
(b) Briefly describe how you can achieve separation of Niobium and
Tantalum if you are supplied with an ore containing the two elements.
(5 marks)
(c) One of the uses of Tantalum is in repair of damaged bones. Briefly
explain why it is preferred to iron which is otherwise part of the blood
hemoglobin. (3 marks)
3. You are required to prepare and characterize a complex of Fe3+ and the
oxalate anion, C2O4
2-. Given the equation
2 2 1.2 . 2
2 2
2 4
2 Fe C O Fe CO E cell V
o ? ? ? ? ? ? ?
(i) Briefly outline the steps you would follow to obtain the complex
? ? ? ?, 3 2 4 3 K Fe C O giving reasons for your choice of method.
(5 marks)
(ii) What steps would you follow to confirm the Stoichiometry of
the complex. (7 marks)
4. (a) CrCl2 dissolves in water to give the strongly reducing cation
? ? ? ? 2?
2 6 Cr H O and all the halides can be precipitated as Agcl.
On the other hand MoCl2 and WCl2 dissolve in water but only one
third of the halides can be precipitated as AgCl. Briefly explain why
this is so supporting your explanation with relevant structures. (7 marks)
(b) The oxidizing ability of MnO4
-, TCO4
- and ReO4
- decrease in the order
MnO4
- > TCO4
- >ReO4
-. State the oxidation state of the central ion
and explain the trend in oxidizing ability. (2 marks)
(c) Write the electron configurations of the following species. Comment
on any unexpected trend.
(i) 24Cr
(ii) 74W
(iii) 46Pd
(iv) 29Cu+
(8 marks)
3
5. Give possible reasons for the following observations.
(i) Sc3+ compounds are colorless while those of Cr3+ are co loured
green.
(ii) The highest oxide of Fe is Fe2O3 while that of Ru is RuO4.
(iii) V2O5 is such a versatile catalyst.
(iv) TiO2 has replaced white lead 2PbCO3.Pb(OH)2 as a white paint
pigment base.
(v) Gold forms stable MIII halides but copper and silver do not.
(11 marks)
**************
More Question Papers
Popular Exams
Return to Question Papers