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
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J.
Serb. Chem. Soc. 64(12)
821-823 (1999)
SUBJECT INDEX
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J.
Serb. Chem. Soc. 64(12)
825-828 (1999)
AUTHOR INDEX
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End of Volume 64
Copyright & copy;
SHD
1999.
Last Updated December 30,
1999
For more information
contact:
SHD@elab.tmf.bg.ac.yu
