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Volume 18, Issue 4  (2009)

Editorial:
B.V. Toshev
The Project Method in Education

Full text: PDF (194 K)

243
Letters to the Editor:
S. Popova
A Competition between 11-12 Years Young Students to Enhance Their Ecological Culture

Full text: PDF (126 K)

250
Teaching Efficiency:
A. Gendjova, B. Yordanova
Project-Based Learning in Science at the American College of Sofia

Full text: PDF (127 K)

255
Teaching Chemical Experiment:
Mala Das Sharma
Rapid Determination of Partition Coefficients of Some Common Organics between Organic and Aqueous Solvents

Full text: PDF (97 K)

268
Problems:
M. Atanassova
An Alternative Method for Oxidation-Reduction Reactions Balancing

Full text: PDF (108 K)

280
Foreign Educational Tradition:
A. Gendjova
About the History of the Project Method in Education

Full text: PDF (343 K)

286
New Information Media:
S. Zabunov, K. Velichkova
Teaching Physics Using Virtual Laboratory Exercises in the Environment of an Adaptive E-Learning System

Full text: PDF (233 K)

299
Reviews:
M. Milanova, D. Todorovsky
Introduction to the Chemistry of Coordination Compounds

Full text: PDF (134 K)

314
Chemistry & History of Chemistry: An Online Supplement:

CHEMISTRY & HISTORY OF CHEMISTRY III.

Full text: PDF (22 K)

320
S.N. Chadar, F. Khan
Srudy for Dependence of 'Transition State' with Applied Potential in Electrokinetic Reaction of [Zn(II)-Antibiotics-Vitamine-B2] System vis a vis Kinetics of Electrode Reaction

Full text: PDF (68 K)

E73
Man Singh
Econoburette: A Gtreen Chemistry Burette for Microscale Titrations

Full text: PDF (83 K)

E82
V. Jagannadham
The Change in Entropy of Activation Due to Solvation/Hydration - A One Hour Graduate Classroom Lecture

Full text: PDF (43 K)

E89
A. Semnani, A.R. Firooz, H.R. Pouretedal, M.H. Keshavarz
Molecular Complexes of Some Thiacrown Ethers and 1,3,5-Trithiane with Iodine in Dichlormethane and Carbon Tetrachloride Solutions

Full text: PDF (223 K)

E94
M.D. Stojkovic, D.A. Kostic
Utilizing of Contemporary Tools in Teaching Chemistry - Computers, Computer Programs and Internet

Full text: PDF (59 K)

E108
B.V. Toshev
School and Schooling in the Kingdom of Bulgaria: Photoarchives - Part 2 (Education in Urban Areas)

Full text: PDF (496 K)

E119
R. Jain, A. Pandey, S.S. Pandeya
Mechanism of Dissolution of Delayed Release Formulation of Diclofenac Sodium

Full text: PDF (60 K)

E131
 

Khimiya, Volume 18, Issue 4(2009)

Khimiya. 18, 243- (2009) Author(s): B.V. Toshev:

Abstract.A survey of the basic literature on the project method in education is presented. This method was widely used in America just after the WWI. The role of Kilpatrick and his colleagues from the Teachers College, Columbia University, for the development and dissemination of the method throughout the American schools is emphasized. The symposium on the dangers and difficulties of the project method, held at the Teachers College in 1921, is commented in brief.

Keywords: project method, applications, Kilpatrick, Branom, religious education, project method symposium in 1921

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Khimiya. 18, 255- (2009) Author(s): A. Gendjova, B. Yordanova:

Abstract.This paper presents a research on project-based learning in science at the American College of Sofia. The aim of study is to ascertain if the method used at the college possesses the essential features of contemporary project-based learning, namely, driving questions, active research, autonomy, collaboration, authenticity, artifacts, presentation, curriculum-focused. The research is made by observations on projects activities; the students are interviewed to establish their attitude to this school practice. Some conclusions about the project-based method efficacy, advantages and challenges are drawn.

Keywords: project-based learning, features, research, science education

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Khimiya. 18, 268- (2009) Author(s): Mala Das Sharma:

Abstract.Determination of partition coefficients of (1) acetic acid between n-butanol and water and (2) benzoic acid between water and benzene have been carried out by a different approach, where volumetric titration is completely avoided. This method yields results in excellent agreement with those obtained by conventional titrations. The inherent advantages of the suggested method are its easy execution in reduced time with less number of chemicals.

Keywords: partition coefficient, digital balance, rapid method, classroom teaching

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Khimiya. 18, 280- (2009) Author(s): M. Atanassova:

Abstract.An alternative method for balancing of oxidation-reduction reaction equations is proposed. The method allows easier and without formal admittances determination of stoichiometric coefficients of the corresponding chemical equations.

Keywords: oxidation-reduction reactions, oxidation number method, material balance method

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Khimiya. 18, 286- (2009) Author(s): A. Gendjova:

Abstract.This paper describes the introduction and further development of the method of projects in the school practice. The contributions of Dewey, Kilpatrick and Stimson are specially emphasized. The influence of these pedagogical ideas to the Bulgarian educational theory and practice is also examined. The application of the method of projects in the contemporary primary, secondary and vocational schools should be strongly encouraged.

Keywords: history, project method, education, project-based learning

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Khimiya. 18, 299- (2009) Author(s): S. Zabunov, K. Velichkova:

Abstract.The current work aims at presenting the benefits of the Individually Adaptive Learning Management System (IALMS) during the conducted virtual laboratory exercises in physics. The offered and here presented experiment is in the domain of physics higher education. It was carried out in the Department of Physics at the University of Mining and Geology St. Ivan Rilski - Sofia. The basic qualities of the applied system are exhibited. Some of these virtues are the higher efficiency of the e-learning process and the proposed novel adaptive learning model. The results are achieved by individualization of the educational process in an environment of simulated interactive laboratory exercises, complemented with adaptation of the theoretical educational material.

Keywords: virtual experiment, Individually Adaptive E-learning, Learning Management System, Interactive Physics Laboratory Exercise

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Khimiya. 18, 314- (2009) Author(s): M. Milanova, D. Todorovsky:

Abstract.The book of Dukov, Petrova and Zakhariev gives a short overview of the main problems concerning the chemistry of coordination compounds, such as the nature of the chemical bond, isomerism, equilibrium in solutions, acid-base and redox properties. Special attention is paid to the nomenclature of this type of compounds, following the 2005 IUPAC recommendations. The detailed mechanism of substitution reactions in coordination compounds is presented. Prof. Dr. I. Dukov, DSc., is a university lecturer, specialised in the extraction chemistry of lanthanides. His former Ph.D. student, Dr. M. Petrova is a university teacher as well and has been working in the same scientific field. Dr. Zakhariev, their colleague, works in a different field but with interests in coordination chemistry. The book is of interest for university students, for teachers in both secondary schools and universities as well as for anyone interested in coordination chemistry.

Keywords: coordination compounds, chemical nomenclature

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Khimiya. 18, E73- (2009) Author(s): S.N. Chadar, F. Khan:

Abstract.Polarographic technique was used to study the ternary complex formation of Zn(II) with neomycin, chlortetracycline, oxytetracycline, penicillin-V and penicillin-G as primary ligands and vitamin-B2 as a secondary ligand at pH = 7.30 0.01 and = 1.0 M NaClO4 at 298 K. The nature of current voltage curves was quasireversible. Zn(II) formed 1:1:1, 1:1:2 and 1:2:1 complexes with these drugs as confirmed by Schaap and McMaster method. The sequence of stability constant of complexes was neomycin < chlortetracycline < oxytetracycline < tetracycline < penicillin-V < penicillin-G that can be explained on the basis of nature of ligands and steric hindrance between metals ligands. Kinetic parameters were also determined using Tamamushi and Tanaka method. The value of transfer coefficient (α) confirmed that the transition state behaves between dropping mercury electrode and solution interface. A slight variation of potential affects not only the rate but rate constant greatly.

Keywords: stability constant, kinetic parameter, [Zn(II)-antibiotics-vitamin-B2] complexes

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Khimiya. 18, E82- (2009) Author(s): Man Singh:

Abstract.Econoburette [Calibration No.M/0408/10970 by Testing Centre, Ministry of MSME, Govt. of India, New Delhi] is a green chemistry instrument to perform valuable titration with microlitres of liquid samples. The microlevel amounts of titer and titrant consume less time in doing a volumetric tititration and also prevent escape of materials. In general, after titration a significant quantity of indicator, additive, titer and titrant are consumed and drained out in sink to cause air, water and soil pollutions. The econoburette prevents such wastages by nine times with high accuracies in results with no pipetting an aliquot.

Keywords: econoburette, titration, microlitre, titer, pollution

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Khimiya. 18, E89- (2009) Author(s): V. Jagannadham:

Abstract.The significance of change in entropy of activation for two different reactions where in one involves the liberation of a proton and the other a carbocation is described based on the fact that the hydration of a proton involves a loss in entropy due to freezing of translational, rotational or vibrational degrees of freedom of solvent molecules.

Keywords: entropy, proton, carbocation, salvation, hydration

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Khimiya. 18, E94- (2009) Author(s): A. Semnani, A.R. Firooz, H.R. Pouretedal, M.H. Keshavarz:

Abstract.A spectrophotometric study concerning the interaction between 1,3,5- trithiane (TT), trithia-9-crown-3 (TT9C3), tetrathia-12-crown-4 (TT12C4) and hexathia-18-crown-6 (HT18C6) as n-donor with iodine as sigma-acceptor has been performed in dichloromethane and carbontetrachloride solutions. The results are indicative of the formation of 1:1 molecular complexes through equilibrium reactions in both solvents. The stability constants of the reactions were evaluated from the fitting of absorbance vs. mole ratio data in MATLAB software. The results indicate that in both solvents stabilities vary in the order: TT - TT12C4 - TT9C3 - HT18C6. Also, the results are indicative of the formation of more stable complexes in CCl4 than of CH2Cl2. These observations are interpreted based on the structural features of donors and specifications of solvents. The reverse trend of epsilon values and higher epsilon values in CH2Cl2 than that of CCl4 are the other discussed results.

Keywords: spectrophotometry, thiacrown ethers, iodine, dichloromethane, carbontetrachloride

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Khimiya. 18, E108- (2009) Author(s): M.D. Stojkovic, D.A. Kostic:

Abstract.Utilization of modern computer aids represents an innovative model and method on which modern chemistry teaching is based. The possibility to apply the innovative methods in teaching chemistry, the use of computers, computer programs and the Internet, are based on the conducted practice and theoretical work in primary schools. Simplification of rules, phenomena, laboratory procedures, and complex molecular structures is based on the simplicity in work, the use and application of computer aids. The aim of the research paper is to point to the advantages of computer programs and the Internet in presentation, practice and explanation of teaching material in chemistry, as opposed to traditional technical means. Moreover, it popularizes, modernizes, develops, and perfects the existing models and methods of teaching chemistry by using computer science and computer aids.

Keywords: chemistry teaching, computers, computer programs, computer teaching aids, internet, students

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Khimiya. 18, E119- (2009) Author(s): B.V. Toshev:

Abstract.At the Research Laboratory on Chemistry Education and History and Philosophy of Chemistry, University of Sofia, a collection of photos and other documents illustrating the school and schooling in the Kingdom of Bulgaria (1878-1946) has been established. These photos have a historical value. Some of these photos, presenting various details of the gymnasia education, are shown. The publication of such materials will continue in future.

Keywords: Kingdom of Bulgaria, educational system, gymnasia, pedagogical schools, school life

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Khimiya. 18, E131- (2009) Author(s): R. Jain, A. Pandey, S.S. Pandeya:

Abstract.Diclofenac sodium [o-(2,6-dichloranilino) phenyl] acetate is a potent non steroidal drug (NSAID) and used as an anti-inflammatory and analgesic agent; is one of the least soluble compounds even though present as sodium and potassium salt. In present study we are trying to increase the dissolution rate of that poor water soluble drug by the solubilization capacities of micellar solution of diblock copolymer polyethylene glycol 400. The max is obtained at 276nm , and the Beers law is obeyed up to 5 to 50g/ml.The critical micellar concentration (CMC) of polyethylene glycol 400 was found at 1.25.10-3 mol/L by UV method. The different polymicellar concentrations of PEG were used to verifying how the different dissolution media would influence the release drug characteristics. The mechanism of drug release was determined using the Korsmeyer-Peppas model.

Keywords: diclofenac sodium, polymeric micelles, polyethylene glycol 400, Korsmeyer-Peppas model, delayed formulation

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