The nature of the ferric thiocyanate complexes

226 Pages·036.946 MB·English

by  Mitchell, Kenneth McLean

T H E N A T U R E O F T H E
F E R R I C T H I O O Y A N A T E
C O M P L E X E S
A Tliesis by
KENNETH MoLBAN MITCHELL
presented to the
UNIVERSITY of St.ANDREWS
in application for the degree
of Doctor of Philosophy
1951
ProQuest Number: 10171226
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RESSAROH TRAINING AND EXPERIENCE
I first matriculated at the University of St.Andrews
in October 1942 and graduated Bachelor of Science in
June 1945, being subsequently awarded first class
Honours in Chemistry in June 1946, In October of
that year, I was enrolled as a Research Student under
the direction of Dr,J,Y.Macdonald, During session
1948-9, I worked on a problem in kinetics at the
School of Chemistry in the University of Alabama,
U.S.A., and was awarded the degree of Master of
Science of that University. Thereafter, I returned
to the University of St.Andrews and completed the
research work, herein described, by January 1950.
D B O L A R A T ï 0 N
I, hereby declare that the following dissertation
is a record of work carried out by me, that it is
my own composition, and that it has not been accept­
ed in any previous application for a higher degree*
The work was carried out in the Chemical Research
0^ UtuJtsA
^
Laboratory^in the University of St.Andrews under
the direction of Dr.J.Y*Macdonald.
C E R T I F I C A T E
1
certify that Kenneth Mo.Lean Mitchell has spent
nine terms at research work under my supervision,
that he has fulfilled the conditions of Ordinance
No.16 (St.Andrews) and that he is qualified to
submit the accompanying thesis in application for
the degree of Doctor of Philosophy.
C O N T E N T S
I N T R O D U C T I O N
AIMS OF RESEARCH ON FERRIC THIOCYANATB . . 9
PART 1
PREPARATION OF SOLUTIONS AND SOLVENTS . . 17
2
PART
THE MOLECULAR STATE OF FERRIC THIOCYANATE
IN ORGANIC SOLVENTS . . 20
APPARATUS 23
Standardisation of the Ebulliometer and the Procedure
for its use 26
1. Rate of Ebullition 26
2. Calibration of Thermometers • • » • • • 27
3. Summary of Procedure 28
4* Heat Loss 28
5. Analysis of Solutions 29
èXPERIMBNÏAL 30
52
Experiments to test thee bulliometer • . •
Bbulliosoopic Constants for Moist Ether and
Dry Alcohol ................................ 35
Preparation of solutions of Ferric Thiocyanate 37
E^erimental Results * ................ 40
Conclusion 43
A NOTE ON THE ELECTRICAL CONDUCTIVITY OF ETHEREAL
SOLUTIONS 44
PART 3
THE PARTITION OF FERRIC THIOCYANATE
BETWEEN WATER AND ETHER . • 49
EXPERIMENTAL 56
DISCUSSION . . . . . . . 66
PART 4
THE STABILITY CONSTANTS OF THE FERRIC
THIOCYANATE COMPLEXES • # 78
The relationship between kq and k^ , k^ and kg ,
kg arid k^ # . 80
Simplification of the Partition Equation by the
Theory postulated by Bjerrum . . . . . . . 82
Algebraic Solution of the Partition Equation . . 83
EVALUATION OF THE CONSTANTS *k^» aanndd ’K^> . . 85
Discussion . . . . ........... . . . . . . . 90
PART 5
APPLICATION OP SPBGTROGHBMICAL ANALYSIS
TO THB STUDY OP THE PBRRIG
THIOCYANATE COMPLBXSS . . 100
THEORY OP SPBGTROGHEMIGAL ANALYSIS 102
CONSTRUCTION'. CALIBRATION, AND PROCEDURE FOR USE OP
THE PHOTOELECTRIC SPECTROPHOTOMETER 106
INTRODUCTION 106
Light Source 108
Monochrometor 109
Optical Cells and Cell Carriage • ♦ • * . 109
Photoelectric Cell . . . . . . . . 110
Galvanometer . . 110
CALIBRATION OF THE SPECTROPHOTOMETER . . 112
Photoelectric Cell . . . . . . . . . . 112
Wavelength Sensitivity Curve . . . . . 112
Linearity of Response . . . . . . . . 114
Monochrometer 118
Colour Filters . . . . . 118
Slit Width and Band Width ............ 122
PROCEDURE ' 127
THE STABILITY CONSTANT OF THE COMPLEX FeCNS^^ . . 129
THEORY 130
EXPERIMENTAL 133
A - The Absorption Spectra of Ferric Thiocyanate
Solutions containing a range of iron
Concentrations . . . . . . . 133
*
B - The Determination off the Stability
Constant of FeCNS^"*" . . . . . . . 138