JSCS Vol 64, No. 12
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J. Serb. Chem. Soc.
64(12) 721-735 (1999)
UDC
666.762.65:543.422/.51
JSCS-2711
Original scientific paper
Ab initio study of the electronic
spectrum of BeO
IVANA ADAMOVIC, MAJA PARAC, MICHAEL HANRATH* and MILJENKO PERIC*
Faculty of Physical Chemistry,
University of Belgrade, Studentski trg 16, YU-11000 Belgrade, Yugoslavia and
**Institut für Physikalische und Theoretische Chemie, Universität
Bonn, Wegelerstrasse 12, D-53115 Bonn, Germany
(Received
11 June 1999)
Low-lying
singlet and triplet electronic states of the BeO molecule are calculated by
means of the quantum chemical ab initio method. It was found that all states in
the energy range from 0 to 50000 cm-1 are of
valence character. Particular attention was paid to the investigation of the
dissociative behavior of the states considered. The vibrational structure of the
AIP<-XIS and BIS+<-XIS+ spectral systems was calculated.
Keywords:
electronic spectrum, ab initio calculations, valence - Rydberg interaction
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J.
Serb. Chem. Soc. 64(12) 737-744 (1999)
UDC 548.562:543.226
JSCS-2712
Original scientific
paper
On the nature of crystallization water
using thermal analysis. - The application to some hydrates with different
cations
LUCIA ODOCHIAN, DANA MAGDELENA PANTEA**, IRINA CALUGAREANU, DANA
IONESCU and OLGA VICOL*
Department of Physical Chemistry,
"Al. I. Cuza" University, Iasi, Rumania,
*Department of Inorganic Chemistry, "Al. I. Cuza"
University, Iasi, Rumania and
**Department of Chemical Engineering, Laval University, Quebec,
Canada
(Received 2 December
1998, revised 25 March 1999)
The nature of the crystallization water in some
hydrates with different cations, namely: MnSO4·H2O; FeSO4·7H2O; CoSO4·7H2O; NiSO4·7H2O, has been studied by the application of the
following non-isothermal techniques: thermogravimetry (TG), derivative
thermogravimetry (DTG), and differential thermal analysis (DTA). Analysis of
the characteristic thermogravimetric data (Tm, Wµand of the kinetic parameters (n, Ea) calculated from DTG and DTA data - with CuSO4·5H2O as a reference - demonstrated the existence of
crystallization and anion water in the studied hydrates. The activation energy
of the process of anion water elimination does not depend on the nature of the
cation. This conclusion was confirmed by the absence of the compensation effect
in this process.
Keywords:
crystallization water, TG-DTG-DTA, kinetics, hydrates.
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J.
Serb. Chem .Soc. 64(12) 745-752 (1999)
UDC 546.74'331''(669.245)
JSCS-2713
Original scientific
paper
Examination of the kinetics of Zr1.02Ni0.98 alloy
hydriding
BRANISLAV R. SIMONOVIC*, SLAVKO V. MENTUS and MILENKO V. SUSIC
*Institute of Chemistry, Technology
and Metallurgy, Njegoseva 12, Belgrade and Faculty of
Physical Chemistry, University of Belgrade, Studentski trg 12,
Belgrade, Yugoslavia
(Received 15 March 1999)
The hydriding kinetics of Zr1.02Ni0.98 alloy was examined in dependence on the number
of hydriding/dehydriding cycles. The rate constants relating to three
subsequent hydriding procedures of an alloy sample, at five temperatures: 423,
448, 473, 498 and 523 K, were determined. The rate constant increases, and the
activation energy decreases on each repetition of the hydriding/dehydriding
cycle at a given temperature. This behavior was explained by sample crushing,
leading to an increase in the surface area accessible to hydrogen.
Keywords:
hydriding/dehydriding, zirconium-nickel alloy, hydriding rate constant,
activaiton energy.
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J.
Serb. Chem. Soc. 64(12) 753-764 (1999)
UDC 549.324.31:66.094.3:546.215(546.185-325)
JSCS-2714
Original scientific
paper
Kinetics of pyrite oxidation by
hydrogen peroxide in phosphoric acid solutions
MILE DIMITRIJEVIC, MILAN ANTONIJEVIC* and VALENTINA DIMITRIJEVIC
1Copper Institute, Zeleni bulevar
35, YU-19210 Bor
2Technical Faculty Bor, University of Belgrade, VJ 12, YU-19210
Bor, Yugoslavia
(Received 16 February,
revised 29 June 1999)
The kinetics of pyrite oxidation by hydrogen
peroxide in phosphoric acid solutions were investigated. The effects of
stirring, temperature, and particle size, as well as of the hydrogen peroxide
and phosphoric acid concentrations were studied. The effect of phosphate ion
addition was also examined. The oxidation kinetics was found to follow a
shrinking core model, with the surface chemical reaciton as the
rate-controlling step. This is in accord with an activation energy of 57 kJ mol-1 and a linear relationship between the rate constant and the
reciprocal of the particle radius. The reaction order with respect to the
hydrogen peroxide concentration was found to be equal to unity. Variation of
the phosphoric acid concentration had practically no effect on the rate of
pyrite oxidation. Addition of the phosphate ion in the relatively low
concentration range (0.005-0.1 mol dm-3) had a highly negative
influence on the rate of pyrite oxidation, indicating that this ion has an
inhibiting effect on the oxidation of pyrite by hydrogen peroxide.
Key
words: pyrite, oxidation, reaction kinetics, hydrogen peroxide, phosphoric
acid.
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J. Serb. Chem. Soc. 64(12) 765-774 (1999)
UDC 546.621' 73'' 76''' 77'''' :
669.017.1:536.777
JSCS-2715
Original scientific
paper
Determination of the thermodynamic properties
for Cr-Co-Me (Me = Mo, Al) systems by using the general solution model for
predicting
DRAGANA T. ZIVKOVIC and ZIVAN D. ZIVKOVIC
Technical Faculty, University of
Belgrade, VJ 12, YU-19210 Bor, Yugoslavia
(Received
9 February, revised 22 June 1999)
The
results of the determination of the thermodynamic properties for ternary
systems Cr-Co-Me (Me = Mo, Al) using a new general solution model for the
predictions are presented in this work. For five sections (with mole ratio Co :
Me = 2:8, 4:6, 5:5, 6:4, 8:2) investigated in each ternary system at
temperature of 2000 K, integral molar excess Gibbs energies and partial molar
thermodynamic properties of chromium were calculated.
Keywords:
alloy thermodynamics, thermodynamic predicting, ternary systems, Cr-Co-Mo
system, Cr-Co-Al system
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J.
Serb. Chem. Soc.64(12)775-787(1999)
UDC 547.752:535.243/.651
JSCS-2716
Original scientific
paper
Spectrophotometric study of the
protonation processes of some indole derivatives in sulfuric acid
BLAGOJA S. ANDONOVSKI and GORAN M. STOJKOVIC
Institute of Chemistry, Faculty of
National Sciences, University "Sv. Kiril i Metodij", P.O.Box 162,
91001 Skopje, Macedonia
(Received 30 October
1998, revised 8 July 1999)
The protonation of 3-methylindole, D-tryptophan,
3-formylindole, 3-acetylindole and indolyl-2-carboxylic acid in sulfuric acid
media was studied by UV spectro-scopy. The measurement of the absorbance at
four selected wavelengths enabled the calculation of the corresponding molar
absorptivities. The results were used to calculate the pKa value of the
protonated form of the indole derivatives by the Hammett Method. The Hammett
postulate (the slope of the plot log [c(BH+)/c(B)] vs. H should be equal to 1) was tested. The
dissociation constants and solvent parameter m* were also obtained by
applying the Excess Acidity Method. The position of the additional protons in
the protonated compounds is discussed.
Keywords:
3-methylindole, D-tryptophan, 3-formylindole, 3-acetylindole, indolyl-2-carboxylic
acid, protonation, dissociation constants, solvent parameter, Hammett Acidity
Function Method, Excess Acidity Method.
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J.
Serb. Chem. Soc. 64(12) 789-793 (1999)
UDC 66.063.762.841.42:66.061:62.001.57
JSCS-2717
Original scientific
paper
Self-association and association of
tri-n-butyl phosphate (TBP) in different diluents
JOZEF J. COMOR, MIROSLAV M. KOPECNI and DJORDJE M. PETKOVIC
Vinca Institute of Nuclear
Sciences, P.O. Box 522, YU-11001 Belgrade, Yugoslavia
(Received
10 June, revised 3 September 1999)
The
interaction of tri-n-butyl phosphate (TBP) with diluents and its
self-association have been investigated. The corresponding equilibrium
constants were determined and used to calculate the concentration of TBP
monomer. The calculated TBP monomer concentrations correspond to the TBP
activities published in the literature.
Keywords:
self-association, association, tri-n-butyl phosphate (TBP), extraction model,
TBP activity.
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J.
Serb. Chem. Soc. 64(12) 795-800 (1999)
UDC 537.5:621.352
JSCS-2718
Short communication
SHORT COMMUNICATION
The
current distribution in an electrochemical cell. Part V. The determination of
the depth of the current line penetration between the edges of the electrodes
and the side walls of the cell
KONSTANTIN I. POPOV, SLAVISA M. PESIC* and TANJA M. KOSTIC
Faculty of Technology and
Metallurgy, University of Belgrade, Karnegijeva 4, P.O.Box 494, YU-11001 Belgrade
and
*Ei-Stampana kola, Printed Circuit Board Factory, Bul. Cara
Konstantina 80-84, YU-18000 Nis, Yugoslavia
(Received 24 June 1999)
A method for the calculation of the depth of the
current line penetration between the edges of the electrodes and the side walls
of the cell in a cell with plane parallel electrode arrangement is proposed.
The method is verified by the calculation of the polarization curves for the
cells in which the electrode edges do not touch the side walls of the cell. The
agreement between the calculated and the measured values was fair.
Keywords:
metal electrodeposition, electrochemical cell, current distribution.
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J. Serb. Chem. Soc. 64(12) 801-811 (1999)
UDC 547.21:66.095.12:536.71/.722
JSCS-2719
Original scientific
paper
Application of the MvdW1 and
HVOS-NRTL mixing rules to the simultaneous correlation of excess enthalpies and
W-shaped excess heat capacities data of 1,3-dioxolane + n-alkane systems
BOJAN D. DJORDJEVIC, MIRJANA LJ. KIJEVCANIN, ALEKSANDAR Z. TASIC
and
SLOBODAN P.
SERBANOVIC
Faculty of Technology and
Metallurgy, University of Belgrade, Karnegijeva 4, YU-11120-Belgrade,
Yugoslavia
(Received 12 September
1999)
The Peng-Robinson-Stryjek-Vera (PRSV) equation
of state (EOS) coupled with a modified two parameter van der Waals one-fluid
mixing rule (MvdW1) and the Huron-Vidal-Orbey-Sandler mixing rule incorporating
the NRTL equation as a GE model was used for the
correlation of excess enthalpy (HE), excess heat capacity
(CpE) and the simultaneous correlation of both properties. All
calculations with temperature dependent parameters of EOS models were applied
to 1,3-dioxolane+n-alkane systems.
The correlation of the HE and CpE data alone with four coefficients and the HE+CpE data with six coefficients of the temperature dependent
parameters of the HVOS-NRTL models could be considered as very satisfactory.
Keywords:
equation of state, mixing rule, excess properties, 1,3-dioxolane, n-alkane.
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J.
Serb. Chem. Soc. 64(12) 813-814 (1999)
PROFESSOR JOHN M. PRAUSNITZ
On the occasion
of his 70th birthday
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J. Serb. Chem. Soc. 64(12) 815-820 (1999)
CONTENTS OF VOLUME 64
To download Contents of Vol 64 click here (538 KB WinZip file)
J.
Serb. Chem. Soc. 64(12) 821-823 (1999)
SUBJECT INDEX
To download Subject Index click here (60 KB WinZip file)
J.
Serb. Chem. Soc. 64(12) 825-828 (1999)
AUTHOR INDEX
To download Author Index click here (46 KB WinZip file)
End of Volume 64
Copyright & copy; SHD 1999.
Last
Updated December 30, 1999
For
more information contact: SHD@elab.tmf.bg.ac.yu