|Letters to the Editor:|
How to Measure the School Outcome (On the Example of a Specific Educational Goal) [In Bulgarian]
Full text: PDF (826 K)
|J. Stefanova, M. Minewska|
Perceptions of the World: The Role of Scientific Explanation in Science Education for Forming the Worldview of Students [In Bulgarian]
Full text: PDF (809 K)
|B. V. Toshev|
Conceptual Scheme of School Course of Chemistry: Macroscopic Approach [In Bulgarian]
Full text: PDF (1155 K)
|S.S. Aswale, S.R. Aswale, A.B. Dhote|
Role of Ultrasonic Waves to Study Molecular Interactions in Aqueous Solution of Diclofenac Sodium
Full text: PDF (1001 K)
|J. Malakar, A.K. Nayak|
Simultaneous Estimation of Iboprofen and Ranitidine Hydrochloride Using UV Spectrophotometric Method
Full text: PDF (835 K)
Computer-Aided Educational Technologis in the Laboratory Exercises in Physics [In Bulgarian]
Full text: PDF (905 K)
A New Formal Geometrical Method for Balancing Continuum Classes of Chemical Reactions
Full text: PDF (806 K)
Dependence between Structure and Properties of Compounds of p- Elements [In Bulgarian]
Full text: PDF (1129 K)
|M.I. Luleva, H. vander Werff, F. van der Meer, V. Jetten|
Gaps and Opportunities in the Remote Sensing for Soil Erosion Assessment
Full text: PDF (332 K)
|Personalities in Science:|
|B. V. Toshev|
Radiochemistry and Archeometry: Prof. Ivelin Kuleff, DSc (Interview) [In Bulgarian]
Full text: PDF (4986 K)
Interactive Methods in "Chemistry and Environment" School Subject [In Bulgarian]
Full text: PDF (1142 K)
A Modern Manual for Active Learning in Science [In Bulgarian]
Full text: PDF (949 K)
Khimiya, Volume 21, Issue 5(2012)
Khimiya. 21, 655- (2012) Author(s): J. Stefanova, M. Minewska:
Abstract.Everyone has his/her own view of the surrounding world. The school has a significant role in shaping these views. Therefore, targeted actions are needed in the classroom to build an adequate scientific insight and understanding of the relations: human ??? nature and human - society. The explanation is a cornerstone of science education. Roads to enforce the educational process in the development of the student's worldview are outlined in this article.
Keywords: worldview, scientific explanation, philosophy of education
Khimiya. 21, 669- (2012) Author(s): B. V. Toshev:
Abstract.A possible scheme of hierarchical introducing the basic concepts and terms in the school course in chemistry is advocated. Following the former Bulgarian educational tradition, it is done within the macroscopic methodological approach and the introduction of modern ideas about the structure of matter and chemical reactions is left for the second level of the Bulgarian secondary education - XI and XII class.
Keywords: macroscopic, microscopic and symbolic domains in chemistry, basic concepts and terms, misconceptions, chemical equilibrium
Khimiya. 21, 684- (2012) Author(s): S.S. Aswale, S.R. Aswale, A.B. Dhote:
Abstract.Ultrasonic is a powerful nondestructive technique having wide range of applications in the field of material science. When ultrasonic wave passes through the medium these waves can actively interact with medium and activate the different processes in the medium. Structural changes occurring in the medium are explained in the form of velocity of propagation and amplitude of absorption. These two parameters are used as a function of temperature, pressure and frequency to evaluate several thermo acoustic parameters which gives detailed information about the molecular interaction. Ultrasonic velocity, density and viscosity measurements of Dichlofenac sodium in aqueous media have been made at different concentrations, temperatures and at different frequencies such as 2MHz, 4MHz and 6MHz.The data obtained during the investigation may give information regarding drug absorption, transmission and effect of the drug.
Keywords: ultrasonic wave, molecular interaction
Khimiya. 21, 692- (2012) Author(s): J. Malakar, A.K. Nayak:
Abstract.A new method has been developed for the simultaneous estimation of ibuprofen and ranitidine HCl using UV spectroscopy. The calibration graphs were linear in the ranges of 2-12 ???g/ml for ibuprofen (r2 = 0.9994) and 5-30 ???g/ml for ranitidine HCl (r2 = 0.9992). The values of limit of detection (LOD) and limit of quantification (LOQ) were determined 0.0196 and 0.0656 for ibuprofen and 0.0114 and 0.0379 for ranitidine HCl, respectively. RSD values for various determinations were found less than 1, which indicated good accuracy and precision of the method. The newly developed method was successfully applied for simultaneous estimation of two combination drugs, ibuprofen and ranitidine HCl in pharmaceutical tablets containing ibuprofen and ranitidine HCl.
Keywords: ibuprofen, ranitidine hydrochloride, simultaneous estimation, UV spectroscopy
Khimiya. 21, 700- (2012) Author(s): G. Kalpachka:
Abstract.The paper gives a proper example for using the computer-aided educational technologies in teaching practice in school. It is described how to realize a physics laboratory exercise named ???determination of gravity acceleration with mathematical pendulum???.
Keywords: computer-aided educational technologies, laboratory exercises in physics, multimedia programs
Khimiya. 21, 708- (2012) Author(s): I.B. Risteski:
Abstract.. In this article a new formal geometrical method is developed for balancing continuum class chemical reactions. Here are treated new continuum classes of aliphatic hydrocarbon chemical reactions which possess atoms with integer oxidation numbers. All considered continuum reactions are reduced to a set of hyperplanes, which intersection is a hyperline that contains the required coefficients of reactions. Also, particular reactions derived from the general continuum classes are balanced in such a way that they do not lose their continuum properties. To this method is given an advantage, because the so-called chemical ways for balancing chemical reactions are inconsistent. Actually, here offered geometrical method is the first scientific method, which treats chemical reactions as n-dimensional geometric entities. By this method, the author proved again that balancing chemical reactions does not have anything to do with chemistry, because it is a pure mathematical subject.
Keywords: geometrical method, chemical reactions, balancing
Khimiya. 21, 726- (2012) Author(s): E. Kirkova:
Abstract.In this paper, some examples of tetrahedral and octahedral structures are given as one of the kinetic factors that affect the stability of compounds of p-elements. The tetrahedral structure is typical for second period elements whose atoms have four valence orbitals. This configuration could be realized by different ways: acceptance of electron pairs ([BF4] -), use of 4 single electrons (??????4), donation of electron pairs (NH4+), formation of hydrogen bonds (the oxygen atoms in ice). Oxides, oxide polymers, oxyanions with the general formula ??????4n- and some oxyacids of the third and next periods elements also typically have a tetrahedral coordination. However, in most cases an octahedral configuration is formed. For light p-elements it is realized by sp3d2-hybridization ([AlF6]3-, [SiF6]2-) but for heavier elements it is formed by electrostatic interactions. The covalent and electrostatic part of bonding is explained qualitatively by the SnS2 structure. A number of compounds of the p-block elements from the long periods, some of which form adducts, exemplify the octahedral structure.
Keywords: tetrahedral and octahedral structures, p-elements, hybridization, electrostatic interactions, adducts
Khimiya. 21, 748- (2012) Author(s): M.I. Luleva, H. vander Werff, F. van der Meer, V. Jetten:
Abstract.Remote sensing data provide spatial information of the Earth surface and are used, amongst various applications, for obtaining information on soil erosion parameters, such as vegetation cover, topography and soil moisture. The use of high spectral resolution information remained however limited. This paper provides an overview of common applications of remotely sensed data in soil erosion studies. We then discuss integration of high resolution spectral data in soil erosion studies, and explain and propose the use of spectroscopy of chemical elements for soil particle tracing as a method for assessment of soil erosion and deposition.
Keywords: soil erosion, remote sensing, soil particle tracing
Khimiya. 21, 777- (2012) Author(s): A. Tafrova-Grigorova:
Abstract.The active and interactive instruction in Chemistry and Environment Protection School Subject is a useful educational resource for chemistry teachers. Authors present the main features of active and interactive methodology in science education. They have chosen several interactive techniques to demonstrate their application in 7 and 8 grades chemistry lessons.
Keywords: active & interactive methods, chemistry education, interactive multimedia presentation
Khimiya. 21, 781- (2012) Author(s): A. Tafrova-Grigorova:
Abstract.The active learning in science is a textbook written as part of the international project ???Student Active Learning in Science??? (SALiS). Academics and educators at ten partner institutions from six countries: Georgia, Bulgaria, Germany, Ireland, Israel and Moldova participate in this project to promote modern teaching and learning strategies in science education. The book comprises three chapters, bibliography and three appendixes. Authors present the aims of school science education, such as development of scientific literacy, procedural skills and positive attitudes towards science. They give a classification of active science teaching and learning strategies along with their main features, and the application of chemical experiments in inquiry and problem-based student-centered teaching. In addition, some examples of active learning through simple, low-cost experiments and activities are given. The Active Learning in Science would be of great help for pre- and in-service science teachers, academics and educators.
Keywords: active learning strategies, student-centered teaching, chemical experiments