Обучение по природни науки и върхови технологии

2016/6, стр. 891 - 902

THE EFFECT OF KOH AND KCL ADDITION TO THE DESTILATION OF ETHANOL-WATER MIXTURE

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Introduction

Energy crisis led to rising fuel prices globally. It was challenged the word to explore alternative energy sources that are renewable and environmentally friendly, one of them is bioethanol. Generally, bioethanol is made from plants containing sugar derivatives such as sugar cane, sweet sorghum and beets and other starchy crops such as maize, cassava, yam and sago. Excess ethanol as an energy source is renewable energy, it can also reduce emissions as a result of carbon monoxide (Bailey, 1996).

High purity of ethanol is required for fueling objective. Meanwhile, the bioethanol processing into ethanol through fermentation and distillation only produce 35-40% of ethanol (Razmovski & Vučurović, 2012). It is known that the ethanol-water mixture provide an azeotrope point in destillation process under atmopheric pressure. The azeotrope point is when the composition of liquid and vapor similar and it become difficult to separate by the usual distillation. Therefore, other methods are needed to separate the azeotropic mixture of ethanol-water, one of them is the addition of electrolytes. The electrolytes must have special characteristics to achieve the desired separation as follows: their ability to break the azeotrope, ease of handling, low toxicity, simple recoverability and selective dissolution (Lladosa et al., 2007; Soares et al., 2015). NaOH is an electrolyte that is commonly used in the industry of ethanol production. However, actually NaOH addition on ethanol production may harm the environment. It because the sodium ions can replace calsium or magnesium ions (soil nutrients) in the soil, then damage the soil structure and pores, decrease cycle of water molecules and air, decrease the bioactivity and transfer of nutrients in the soil, and also increases the water release from soil. High concentration of sodium ions in soil also increase the pH of soil and poisons the plants (Halliwell et al., 2001; Laurenson et al., 2012). Therefore, it is necessary to study other substances to replace NaOH, that has similar function on destillation but provide no harmness to environment.

KOH and KCl provide similar properties with NaOH which are strong electrolyte, soluble in water in which the solubility of NaOH in water is 1110 g/L, the solubility of KOH in water is 1210 g / L and the solubility of KCl in water is 279 g/L. In addition, kalium ions in KOH and KCl are a kind of macro nutrient that is required for plant growth (Gunadi, 2009).

The addition of electrolytes might change the colligative properties of solution. Colligative properties are properties as the function of dispersed phase quantity. When the electrolyte is dissolved in a liquid, the saturated vapor pressure of the liquid will decrease and lead to increase the boiling point. Therefore, the boiling point of water in mixture is higher than pure water. However, the KOH and KCl molecules in the mixture will cause salting out of ethanol and increase the volatility of ethanol to become easily separate from the mixture (Lei et al., 2014).

A previous study on addition of NaOH and KOH has been conducted to separation of ethanol-water mixture by using a two-column fractional destillation (Stauffer, 2012). The research aimed to produces more ethanol volume toward volume ratio of ethanol-water mixture, as aimed by other research by adding KCl to ethanol-water mixture and produce 98%(v/v) of ethanol (Pinto wt al., 2000).

This research used a vigreux column instead of fractionation column as it was used by other researchers (Pinto et al., 2000; Stauffer, 2012). The effects of electrolyte addition were detected from the change of vapor-liquid equilibrium curve (Hadler et al., 2009), the yield of ethanol as distillate, and the change of thermodynamic parameters.

Experimental

This research used ethanol for analysis (Merck) with purity of 99.9% which then was mixed with distilled water at various composition as depicted in Table 1. The electrolyte used were KOH at pro analysis grade (Riedel-de Haën), pro analysis grade KCl (Merck) and distilled water.

Table 1. Weight and volume composition of ethanol-water mixture

EthanolWaterWeight(%)Volume(mL)Weight(%)Volume(mL)00100100202580804051606060764040801012020901141010951205510012600

Destillation was conducted with vigreux column (Pyrex and Scott) equipped with a thermocontrol (a standardized home made), magnetic stirrer and boiling stone. The scheme of distillation flask is described in Fig. 1. In order to understand the effect of electrolyte, KOH or KCl was added at 1 mol in every kg of ethanol content in the mixture.

Boiling temperature or named as bubble point temperature was recorded when the ethanol-water mixture boiled. Meanwhile, the dew point temperature was recorded when the vapor reached saturation as it was shown by condensation inside the distillation flask. Distillation was stopped when the distillate stopped to drop. Then, the distillate was removed to be analyzed by gas chromatography (Buck Scientific Model 910, FID detector, 30 m Restek MXT-1 column). The experimental procedure, for all the electrolyte investigated, was done in triplicate. All experiments were performed under atmospheric pressure.

1. Hot Plate2. Oil bath3. Disllaon ask4. Thermo control5. Vigreux column6. Condenser7. Water out8. Water in10. Disllate ask9. Adapter

Fig. 1. Scheme of the experiment

The recorded boiling and dew points then were plotted on T-x vapor-liquid equilibrium curve to analyze the present of azeotrope point. The x is the mole fraction of ethanol in water and T is boiling and dew point temperature.

Meanwhile, the colligative properties was investigated through calculation of boiling point elevation, K b, as depicted in Eq (1).

Θ = m . K (1)b

m is the molality of solute (ethanol) and q is the difference of the initial boiling point and the final boiling point. The main consideration of this model is based on the fact that all electrolytes are completely dissociated. In this model, when the electolyte was added, then the mixture become an electrolyte solution, therefore the boling point elevation, q, beared the mean activity coefficient, γ ±, as depicted in Eq (2).

θ = v K bm(1+1)

with m (1 + 1 / γ ±) is the molality of the solute after considering the coefficient activity of solution., v is the stoichimetric amount of positive and negative ions in the solution or mixture.

The Gibbs energy of mixing, ΔG mix, was calculated using Eq (3), the entropy of mixing, ΔS mix, was calculated by Eq (4), and the enthalpy of vapour, ΔH vap, was calculated by Eq (5).

ΔGmix =RT(n1ln x1 + n2ln x2 + n1ln γ1 + n2lnγ2(3))

ΔSmix = -R(n1ln x 1 + n2ln x2 + n1ln γ1 + n2lnγ2(4))

1n a =RH( ) +T1c

Results and discussion

Vapor-liquid equilibrium of ethanol-water binary system

The T-x vapor-liquid equilibrium curve that was developed as variation of ethanol mole fraction whithout electrolyte addition, x, is described in Fig. 2(a). The vapor-liquid equilibrium curves of ethanol-water is compared to other result (Fig. 2(b)) in which the distillation was conducted without electrolyte addition (Carey & Lewis, 1932). The binary system of ethanol-water has azeotrope point at 89% mole fraction at 78.15oC(Carey & Lewis, 1932), The result of this experiment shows closed result at 88% mole fraction at 78.35oC. Typical of both curves are similar, in which at 0 % of ethanol mole fraction or it is known as pure water, the boiling point is at 100 oC, and more content of ethanol lead to decreasing of boiling point. The azeotrop point is at 78.35oC which is lower than the boiling point of pure ethanol (x= 100 % at 78.4 oC). At the azeotrope point, ethanol molecules could not separated from water molecules.

The vapor-liquid equilibrium curve of ethanol-water mixture after the addition on KOH and KCl are described in Fig. 3(a) and Fig. 3(b). It is evident that electrolyte modifies the vapor–liquid equilibrium curve, eliminating the azeotrope and allowing obtaining high purity ethanol. Gil et al. (2008), Lei et al. (2014), Lei et al. (2000), Pinto et al. (2000) and Soures et al. (2015) report that the electrolyte used as entrainer eliminate the ethanol–water azeotrope and change the VLE curve. Potassium cloride is well known as entrainer in extractive distillation of ethanol–water mixtures with a good performance results.

Fig. 2. Vapor-liquid equilibrium curve at 1 atm for ethanol-water mixture. (a) T-x curve; (▲) T-x Carey; (●) T-y Carey; (▬)T-x NRTL; (---) Ty NRTL(Carey & Lewis, 1932); (b) T-x curve of ethanol-water experiment; ( ■ ) Dew point; (■ ) Boiling point (experimental data)

Fig. 3. Ethanol-water-electrolyte equilibrium curve at 1 atm (a) ethanolwater-KOH equilibrium, (b) ethanol-water-KCl

When ethanol molecules were easily removed from the mixture, then the distillate become richer with ethanol than the distillate before electrolyte addition on distillation process. It is supported by GC analysis on the produced distillate. The ethanol content in distillate before electrolyte addition for distillation process is 42.3 %. The ethanol content increase to 58.5 % after addition of KOH and it increase to 64.5 % after addition of KCl. In this studied conditions, the electrolyte that present the better effects is potassium chloride. This fact can be explained by the higher solubility of this electrolyte in water, producing a higher capability of interaction of the ions with the water, causing a higher salting-out effect (Soares et al., 2015).

Fig. 3. shows that the addition of KOH and KCl electrolyte increased the boiling and dew point. It is known that water molecules could interact with ethanol molecules through hydrogen bonding. When the electrolyte was dissolved into the mixture, the electrolyte molecules would dissociate into ions, in which those ions bear charge and having ability on providing coulombic interaction with water and ethanol molecules. The higher interaction of the electrolyte with the more polar component, altering, in this manner, the properties of the system ethanol-water mixtures (Soares et al., 2015). In addition, the water molecules would promptly surround the ions or it is called as hydration process. Therefore, those would reduce the possibility of water molecules to be oriented to ethanol molecules. The proposed mechanism is described in Fig. 4. When the interaction of ethanol-water becomes weak after electrolyte addition, the ethanol molecules will be easily separated from water and it allows elimination of azeotrope point.

Fig. 4. The proposed mechanism of interaction between (a) ethanol-water mixture (b) ethanol-water-electrolyte mixture

Boiling point elevation constant (Kb) of ethanol-water and ethanolwater-electrolyte mixture

Plot of ethanol molality to the change of boiling point is described in Fig. 5(a). The plot shows that the curve follows exponential trend and does not follows the linear relation as it is stated by Eq (1). It indicates that the mixture does not comply to the ideal behaviour of solution due to the electrolyte content. The electrolyte which was dissociate into ions will change the ionic strength of the mixture system and lead to the mixture to deviate from its ideal behaviour. The plot also imply that the boiling point elevation has negative value, indicates that the boiling point was decreased instead of increased. It is caused by the higher volatility of ethanol than water. When the curve is isolated on three point with linear relation (Fig. 5(b)), it is found that the slope value is also negative.

Fig. 5. Graph of solute (ethanol) molality versus boiling point elevation in ethanol-water mixture (a) in the 20-95% (w / w) ethanol (b) in 20-60% (w / w) ethanol, where T is the boiling point of the ethanol-water mixture, T0 is the boiling point of water, me is the molality of solute (ethanol)

Fig. 6. Graph of solute (substance ethanol + electrolyte (KOH and KCl)) molality versus boiling point elevation of ethanol-water-electrolyte mixture (a) in 20-95% (w/w) ethanol (b) in 20-60 % (w/w) ethanol. (♦) ethanol-water-KOH mixture; (■) ethanol-water-KCl mixture, where mez is the molality of solute (ethanolelectrolyte)

When the graph of boiling elevation after the addition of KOH and after the addition of KCl are compared (Fig. 6(a)), it is known that the KCl addition allows lower boiling point than the addition of KOH. Linear plot on the straigh line of both curve imply that the KCl addition produced higher negative slope value than KOH addition.

Thermodynamics parameters

Mixing of ethanol-water and ethanol-water-electrolyte was performed at atmospheric pressure and 25ᴼC. The Gibbs energy and the entropy of mixing were determined using Eqs (3) and (4), where activity coefficient value (g) of ethanol is assumed to be worth one, equivalent with g of water, while coefficient activity of electrolyte from the calculation is 0.69.

Table 2. Gibbs energy of mixing (ΔG mix) (J)

Ethanol(% w)ΔGmix Ethanol-water(J)ΔGmix Ethanol-water-electrolyte(KOH dan KCl)(J)20-3625,98-4931,3740-5301,42-6570,2560-5752,58-6978,4980-4726,93-5900,9090-3304,03-4447,2995-2139,34-3265,69

Table 3. Value of entropy of mixing (ΔS mix)

Ethanol(% w)ΔSmix Ethanol-water(J/K)ΔSmix Ethanol-water-electrolyte(KOH dan KCl)(J/K)2012.1716.554017.7922.056019.3023.428015.8619.809011.0914.92957.1810.96

The Gibbs energy of mixing of ethanol-water at various composition of ethanol are negative (Table 2), indicating the spontenous process of mixing. The polarity of both ethanol and water allows them to mix sponteaneously. Meanwhile, after the addition of electrolyte, the Gibbs energy of mixing becomes more negative, implying spontaneity increasing. The presence of electrolyte in the mixture able to reduce the intermolecular interaction between water and ethanol, and the ions are in strong interaction with water, due to high solubility of ions in water than in ethanol The sponteous mixing process is supported by calculated the entropy of mixing, Δ Smix as it is listed in Table 3.

High value of entropy indicates a disorder arragement of molecules in the mixture. When electrolyte was added, it will break the water-ethanol molecules interaction which arranged regulary, with weaken of water-ethanol interaction then re-arrange the bound between water-electrolyte-ethanol. In a binary system, the gibbs free energy change will has a reverse curve with the entropy, as it can be seen in Fig. 7 (a) and Fig. 7(b). The Fig. 7 shows that the gibbs free energy of mixing will reach the lowest value, in which the mixture form at highest spontaneity, and it will occurs when the mixture shows highest irregularity, confirming by highest entropi value.

Fig. 7. The temperature variation of Gibbs energy and Entropy of mixing: (a) Ethanol-Water (b) Ethanol-Water- electrolyte (KOH and KCl); (▬ ) DGmix/nRT; (▬) DSmix/nR, where n is mols number, R is the general gas constant (8,314 J/mol K), T is room temperature (298 K), X ethanol is ethanol mol fraction

Fig. 8. The Plot of activity at various temperature (a). ethanol-water mixture, (b) ethanol-water-KOH (♦); ethanol-water-KCl. (■)

On the ethanol-water separation through destillation, a heat treatment is required to evaporate the mixture (∆H vap is endothermic). It means that the separation is an endothermic process. It is in agreement with the principle of chemical equilibrium, in which when the mixing of ethanol-water occur spontenously, therefore the reverse process to separate ethanol-water will occurs non-spontaneously. The lowest Gibbs energy and the highest entropy are occured at composition of 0.5 part of ethanol.

Enthalpy of vaporization was determined from a slope of plotting between ln versus 1/T (as it is stated by Eq (5)). In which a is activity of solution. The plot is described in Fig. 8.

The Activity plot (Fig. 8) shows the value of DH vap from ethanol-water mixture is 300.11 kJ/mol. Meanwhile, after electrolyte addition the enthalpy of vaporization increase to 738.43 kJ.mol-1 and 340.23 kJ.mol-1 for KOH and KCl addition, respectively. The addition of KOH in ethanol-water separation has higher positive enthalpy value than KCl. This is due to KOH more soluble in water and ethanol than KCl, so that it required more energy to evaporate the mixture. It means that by add electrolyte, more energy will be required to vaporize the mixture. Therefore, when distillation was set up under boiling point of pure ethanol, the heat will only enough to vaporize ethanol and it become easily to separate from water with dissolved electrolyte.

Conclusions

Addition of electrolyte KOH and KCl to ethanol-water mixture could eliminate the azeotrope point and increase the ethanol content in the distillate by 42.3 % at initial to 58.5 % with KOH addition and 64.5 % with KCl addition.

The addition of electrolyte (KOH and KCl) in ethanol-water mixture caused the change of gibbs energy of mixing, DGmix , to become more negative and the entropy of mixing, DSmix, to become more positive. Both changes indicates that electrolyte addition lead to more spontaneous mixing. Meanwhile, electrolyte addition alows increasing of vaporization enthalpy, DHvap , indicating more energy is required to vaporize the mixture. Therefore, when the distillation system was setup under boiling point of pure ethanol, the ethanol molecules will be easily vaporized without to be followed by water vapor.

Acknowledgements: Authors is grateful to The Directorate General of Higher Education, Republic of Indonesia for funding this research under IbM program at 2015 and also for Sebelas Maret University for support the publication process through Hibah MRG 2016.

REFERENCES

Bailey, B.K. (1996). Performance of ethanol as a transport fuel (pp. 37 – 60). In: Wyman, C.E. (Ed.). Handbook on bioethanol: production and itilization. Washington: Taylor & Francis.

Carey, J.S. & Lewis, W.K. (1932). Studies in distillation. Ind. & Eng. Chem., 24, 882 – 883.

Gil, I.D., Uyazán, A.M., Aguilár, J.L., Rodríguez, G. & Caicedo, L.A. (2008). Separation of ethanol and water by extractive distillation with salt and solvent as entrainer: process simulation. Brazilian J. Chem. Eng., 25, 207 – 215.

Gunadi, N. (2009). Response of potato to potassium fertilizer sources and application methods in andisols of West Java. Indonesian J. Agric. Sci.,10(2), 65 – 72.

Hadler, A.B., Ott, L.S. & Bruno, T.J. (2009). Study of azeotropic mixtures with the advanced distillation curve approach. Fluid Phase Equilibria, 281, 49 – 59.

Halliwell, D.J., Barlow, K.N. & Nash, D.M. (2001). A review of the effects of wastewater sodium on soil physical properties and their implications for irrigation systems. Australian J. Soil Res., 39, 1259 – 1267.

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Lei, Z., Xi, X., Dai, C., Zhu, J. & Chen, B. (2014). Extractive distillation with the mixture of ionic liquid and solid inorganic salt as entrainers. AIChE J., 60, 2994 – 3004.

Lladosa, E., Montón, J. B., Burguet, M.C. & Muñoz, R. (2007). Phase equilibria involved in extractive distillation of dipropyl ether+1-propyl alcohol using 2-ethoxyethanol as entrainer. Fluid Phase Equilibria, 255, 62 – 69.

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CHEMOMETRIC ANALYSIS OF SCHOOL LIFE IN VARNA

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A CONTENT ANALYSIS OF THE RESULTS FROM THE STATE MATRICULATION EXAMINATION IN MATHEMATICS

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SOME CONCEPTS FROM PROBABILITY AND STATISTICS AND OPPORTUNITIES TO INTEGRATE THEM IN TEACHING NATURAL SCIENCES

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2018 година
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ЗДРАВЕ И ОКОЛНА СРЕДА

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X-RAY DIFFRACTION STUDY OF M 2 Zn(TeО3)2 (M - Na, K) ТELLURIDE

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CALIBRATION OF GC/MS METHOD FOR DETERMINATION OF PHTHALATES

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ELECTROSYNTHESIS OF CADMIUM SELENIDE NANOPARTICLES WITH SIMULTANEOUS EXTRACTION INTO P-XYLENE

S. S. Fomanyuk, V. O. Smilyk, G. Y. Kolbasov, I. A. Rusetskyi, T. A. Mirnaya

БИОЛОГИЧЕН АСПЕКТ НА РЕКАНАЛИЗАЦИЯ С ВЕНОЗНА ТРОМБОЛИЗА

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CHEMISTRY: BULGARIAN JOURNAL OF SCIENCE EDUCATION ПРИРОДНИТЕ НАУКИ В ОБРАЗОВАНИЕТО VOLUME 27 / ГОДИНА XXVII, 2018 ГОДИШНО СЪДЪРЖАНИЕ СТРАНИЦИ / PAGES КНИЖКА 1 / NUMBER 1: 1 – 152 КНИЖКА 2 / NUMBER 2: 153 – 312 КНИЖКА 3 / NUMBER 3: 313 – 472 КНИЖКА 4 / NUMBER 4: 473 – 632 КНИЖКА 5 / NUMBER 5: 633 – 792 КНИЖКА 6 / NUMBER 6: 793 – 952 КНИЖКА 1 / NUMBER 1: 1 – 152 КНИЖКА 2 / NUMBER 2: 153 – 312 КНИЖКА

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ON THE POSSIBILITY TO ANALYZE AMBIENT NOISERECORDED BYAMOBILEDEVICETHROUGH THE H/V SPECTRAL RATIO TECHNIQUE

Dragomir Gospodinov, Delko Zlatanski, Boyko Ranguelov, Alexander Kandilarov

RHEOLOGICAL PROPERTIES OF BATTER FOR GLUTEN FREE BREAD

G. Zsivanovits, D. Iserliyska, M. Momchilova, M. Marudova

ПОЛУЧАВАНЕ НА ПОЛИЕЛЕКТРОЛИТНИ КОМПЛЕКСИ ОТ ХИТОЗАН И КАЗЕИН

Антоанета Маринова, Теменужка Йовчева, Ася Виранева, Иван Бодуров, Мария Марудова

CHEMILUMINESCENT AND PHOTOMETRIC DETERMINATION OF THE ANTIOXIDANT ACTIVITY OF COCOON EXTRACTS

Y. Evtimova, V. Mihailova, L. A. Atanasova, N. G. Hristova-Avakumova, M. V. Panayotov, V. A. Hadjimitova

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PARAMETRIC INTERACTION OF OPTICAL PULSES IN NONLINEAR ISOTROPIC MEDIUM

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ДЕЙСТВИЕ НА ГАМА-ЛЪЧИТЕ ВЪРХУ ДЕЗОКСИРИБОНУКЛЕИНОВАТА КИСЕЛИНА

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ТРИ ИДЕИ ЗА ЕФЕКТИВНО ОБУЧЕНИЕ

Гергана Карафезиева

МАГИЯТА НА ТВОРЧЕСТВОТО КАТО ПЪТ НА ЕСТЕСТВЕНО УЧЕНЕ В УЧЕБНИЯ ПРОЦЕС

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NATURAL RADIONUCLIDES IN DRINKING WATER

Natasha Ivanova, Bistra Manusheva

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АДАПТИРАНЕ НА ОБРАЗОВАНИЕТО ДНЕС ЗА УТРЕШНИЯ ДЕН

И. Панчева, М. Недялкова, П. Петков, Х. Александров, В. Симеонов

STRUCTURAL ELUCIDATION OF UNKNOWNS: A SPECTROSCOPIC INVESTIGATION WITH AN EMPHASIS ON 1D AND 2D 1H NUCLEAR MAGNETIC RESONANCE SPECTROSCOPY

Vittorio Caprio, Andrew S. McLachlan, Oliver B. Sutcliffe, David C. Williamson, Ryan E. Mewis

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Veselina Kolarski, Dancho Danalev, Senia Terzieva

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ZAGREB CONNECTION INDICES OF TiO2 NANOTUBES

Sohaib Khalid, Johan Kok, Akbar Ali, Mohsin Bashir

SYNTHESIS OF NEW 3-[(CHROMEN-3-YL)ETHYLIDENEAMINO]-PHENYL]-THIAZOLIDIN-4ONES AND THEIR ANTIBACTERIAL ACTIVITY

Ramiz Hoti, Naser Troni, Hamit Ismaili, Malesore Pllana, Musaj Pacarizi, Veprim Thaçi, Gjyle Mulliqi-Osmani

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GEOECOLOGICAL ANALYSIS OF INDUSTRIAL CITIES: ON THE EXAMPLE OF AKTOBE AGGLOMERATION

Zharas Berdenov, Erbolat Mendibaev, Talgat Salihov, Kazhmurat Akhmedenov, Gulshat Ataeva

TECHNOGENESIS OF GEOECOLOGICAL SYSTEMS OF NORTHEN KAZAKHSTAN: PROGRESS, DEVELOPMENT AND EVOLUTION

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47-А НАЦИОНАЛНА КОНФЕРЕНЦИЯ НА УЧИТЕЛИТЕ ПО ХИМИЯ

В последните години тези традиционни за българското учителство конфе- ренции се организират от Българското дружество по химическо образование и история и философия на химията. То е асоцииран член на Съюза на химици- те в България, който пък е член на Европейската асоциация на химическите и

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BULGARIAN JOURNAL OF SCIENCE AND EDUCATION POLICY ISSN 1313-1958 (print) ISSN 1313-9118 (online) http://bjsep.org

INVESTIGATING THE ABILITY OF 8

Marina Stojanovska, Vladimir M. Petruševski

SYNTHESIS OF TiO -M (Cd, Co, Mn)

Candra Purnawan, Sayekti Wahyuningsih, Dwita Nur Aisyah

EFFECT OF DIFFERENT CADMIUM CONCENTRATION ON SOME BIOCHEMICAL PARAMETERS IN ‘ISA BROWN’ HYBRID CHICKEN

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Преди година-две заедно с директора на Националното издателство „Аз- буки“ д-р Надя Кантарева-Барух посетихме няколко училища в Родопите. В едно от тях ни посрещнаха в голямата учителска стая. По стените ѝ имаше големи портрети на видни педагози, а под тях – художествено написани умни мисли, които те по някакъв повод са казали. На централно място бе портретът на Антон Семьонович Макаренко (1888 – 1939). Попитах учителките кой е Макаренко – те посрещнаха въпроса ми с мълчание. А някога, в г

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„СИМВОЛНИЯТ КАПИТАЛ“ НА БЪЛГАРСКОТО УЧИЛИЩЕ

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KINETICS OF PHOTO-ELECTRO-ASSISTED DEGRADATION OF REMAZOL RED 5B

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ALLELOPATHIC AND IN VITRO ANTICANCER ACTIVITY OF STEVIA AND CHIA

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NOVEL HETEROARYLAMINO-CHROMEN-2-ONES AND THEIR ANTIBACTERIAL ACTIVITY

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Quantum Connement of Mobile Na+ Ions in Sodium Silicate Glassy

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THE EFFECT OF KOH AND KCL ADDITION TO THE DESTILATION OF ETHANOL-WATER MIXTURE

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Министерството на народното просвещение е направило допълне- ния към Правилника за гимназиите (ДВ, бр. 242 от 30 октомври 1941 г.), според които в бъдеще ще се оценяват следните прояви на учениците: (1) трудолюбие; (2) ред, точност и изпълнителност; (3) благовъзпитаност; (4) народностни прояви. Трудолюбието ще се оценява с бележките „образцово“, „добро“, „незадо- волително“. С „образцово“ ще се оценяват учениците, които с любов и по- стоянство извършват всяка възложена им ил

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VOLTAMMERIC SENSOR FOR NITROPHENOLS BASED ON SCREEN-PRINTED ELECTRODE MODIFIED WITH REDUCED GRAPHENE OXIDE

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COMPLEX SYSTEMS FOR DRUG TRANSPORT ACROSS CELL MEMBRANES

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БЛАГОДАРЯ ВИ!

Александър Панайотов

ТЕМАТА ВЪГЛЕХИДРАТИ В ПРОГРАМИТЕ ПО ХИМИЯ И БИОЛОГИЯ

Радка Томова, Елена Бояджиева, Миглена Славова , Мариан Николов

BILINGUAL COURSE IN BIOTECHNOLOGY: INTERDISCIPLINARY MODEL

V. Kolarski, D. Marinkova, R. Raykova, D. Danalev, S. Terzieva

ХИМИЧНИЯТ ОПИТ – НАУКА И ЗАБАВА

Елица Чорбаджийска, Величка Димитрова, Магдалена Шекерлийска, Галина Бальова, Методийка Ангелова

ЕКОЛОГИЯТА В БЪЛГАРИЯ

Здравка Костова

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SYNTHESIS OF FLUORINATED HYDROXYCINNAMOYL DERIVATIVES OF ANTI-INFLUENZA DRUGS AND THEIR BIOLOGICAL ACTIVITY

Boyka Stoykova, Maya Chochkova, Galya Ivanova, Luchia Mukova, Nadya Nikolova, Lubomira Nikolaeva-Glomb, Pavel Vojtíšek, Tsenka Milkova, Martin Štícha, David Havlíček

SYNTHESIS AND ANTIVIRAL ACTIVITY OF SOME AMINO ACIDS DERIVATIVES OF INFLUENZA VIRUS DRUGS

Radoslav Chayrov, Vesela Veselinova, Vasilka Markova, Luchia Mukova, Angel Galabov, Ivanka Stankova

NEW DERIVATIVES OF OSELTAMIVIR WITH BILE ACIDS

Kiril Chuchkov, Silvia Nakova, Lucia Mukova, Angel Galabov, Ivanka Stankova

MONOHYDROXY FLAVONES. PART III: THE MULLIKEN ANALYSIS

Maria Vakarelska-Popovska, Zhivko Velkov

LEU-ARG ANALOGUES: SYNTHESIS, IR CHARACTERIZATION AND DOCKING STUDIES

Tatyana Dzimbova, Atanas Chapkanov, Tamara Pajpanova

MODIFIED QUECHERS METHOD FOR DETERMINATION OF METHOMYL, ALDICARB, CARBOFURAN AND PROPOXUR IN LIVER

I. Stoykova, T. Yankovska-Stefenova, L.Yotova, D. Danalev Bulgarian Food Safety Agency, Sofi a, Bulgaria

LACTOBACILLUS PLANTARUM AC 11S AS A BIOCATALYST IN MICROBIAL ELECYTOLYSIS CELL

Elitsa Chorbadzhiyska, Yolina Hubenova, Sophia Yankova, Dragomir Yankov, Mario Mitov

STUDYING THE PROCESS OF DEPOSITION OF ANTIMONY WITH CALCIUM CARBONATE

K. B. Omarov, Z. B. Absat, S. K. Aldabergenova, A. B. Siyazova, N. J. Rakhimzhanova, Z. B. Sagindykova

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TEACHING CHEMISTRY AT TECHNICAL UNIVERSITY

Lilyana Nacheva-Skopalik, Milena Koleva

ФОРМИРАЩО ОЦЕНЯВАНЕ PEER INSTRUCTION С ПОМОЩТА НА PLICКERS ТЕХНОЛОГИЯТА

Ивелина Коцева, Мая Гайдарова, Галина Ненчева

VAPOR PRESSURES OF 1-BUTANOL OVER WIDE RANGE OF THEMPERATURES

Javid Safarov, Bahruz Ahmadov, Saleh Mirzayev, Astan Shahverdiyev, Egon Hassel

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РУМЕН ЛЮБОМИРОВ ДОЙЧЕВ (1938 – 1999)

Огнян Димитров, Здравка Костова

NAMING OF CHEMICAL ELEMENTS

Maria Atanassova

НАЙДЕН НАЙДЕНОВ, 1929 – 2014 СПОМЕН ЗА ПРИЯТЕЛЯ

ИНЖ. НАЙДЕН ХРИСТОВ НАЙДЕНОВ, СЕКРЕТАР, НА СЪЮЗА НА ХИМИЦИТЕ В БЪЛГАРИЯ (2.10.1929 – 25.10.2014)

2014 година
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145 ГОДИНИ БЪЛГАРСКА АКАДЕМИЯ НА НАУКИТЕ

145 ANNIVERSARY OF THE BULGARIAN ACADEMY OF SCIENCES

ПАРНО НАЛЯГАНЕ НА РАЗТВОРИ

Б. В. Тошев Българско дружество за химическо образование и история и философия на химията

LUBRICATION PROPERTIES OF DIFFERENT PENTAERYTHRITOL-OLEIC ACID REACTION PRODUCTS

Abolfazl Semnani, Hamid Shakoori Langeroodi, Mahboube Shirani

THE ORIGINS OF SECONDARY AND TERTIARY GENERAL EDUCATION IN RUSSIA: HISTORICAL VIEWS FROM THE 21ST CENTURY

V. Romanenko, G. Nikitina Academy of Information Technologies in Education, Russia

ALLELOPATHIC AND CYTOTOXIC ACTIVITY OF ORIGANUM VULGARE SSP. VULGARE GROWING WILD IN BULGARIA

Asya Pencheva Dragoeva, Vanya Petrova Koleva, Zheni Dimitrova Nanova, Mariya Zhivkova Kaschieva, Irina Rumenova Yotova

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GENDER ISSUES OF UKRAINIAN HIGHER EDUCATION

Н.H.Petruchenia, M.I.Vorovka

МНОГОВАРИАЦИОННА СТАТИСТИЧЕСКА ОЦЕНКА НА DREEM – БЪЛГАРИЯ: ВЪЗПРИЕМАНЕ НА ОБРАЗОВАТЕЛНАТА СРЕДА ОТ СТУДЕНТИТЕ В МЕДИЦИНСКИЯ УНИВЕРСИТЕТ – СОФИЯ

Радка Томова, Павлина Гатева, Радка Хаджиолова, Зафер Сабит, Миглена Славова, Гергана Чергарова, Васил Симеонов

MUSSEL BIOADHESIVES: A TOP LESSON FROM NATURE

Saâd Moulay Université Saâd Dahlab de Blida, Algeria

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ЕЛЕКТРОННО ПОМАГАЛO „ОТ АТОМА ДО КОСМОСА“ ЗА УЧЕНИЦИ ОТ Х КЛАС

Силвия Боянова Професионална гимназия „Акад. Сергей П. Корольов“ – Дупница

ЕСЕТО КАТО ИНТЕГРАТИВЕН КОНСТРУКТ – НОРМАТИВЕН, ПРОЦЕСУАЛЕН И ОЦЕНЪЧНО-РЕЗУЛТАТИВЕН АСПЕКТ

Надежда Райчева, Иван Капурдов, Наташа Цанова, Иса Хаджиали, Снежана Томова

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Донка Ташева, Пенка Василева

ДОЦ. Д.П.Н. АЛЕКСАНДЪР АТАНАСОВ ПАНАЙОТОВ

Наташа Цанова, Иса Хаджиали, Надежда Райчева

COMPUTER ASSISTED LEARNING SYSTEM FOR STUDYING ANALYTICAL CHEMISTRY

N. Y. Stozhko, A. V. Tchernysheva, L.I. Mironova

С РАКЕТНА ГРАНАТА КЪМ МЕСЕЦА: БОРБА С ЕДНА ЛЕДЕНА ЕПОХА В ГОДИНАТА 3000 СЛЕД ХРИСТА. 3.

С РАКЕТНА ГРАНАТА КЪМ МЕСЕЦА:, БОРБА С ЕДНА ЛЕДЕНА ЕПОХА, В ГОДИНАТА 000 СЛЕД ХРИСТА. .

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KNOWLEDGE OF AND ATTITUDES TOWARDS WATER IN 5

Antoaneta Angelacheva, Kalina Kamarska

ВИСША МАТЕМАТИКА ЗА УЧИТЕЛИ, УЧЕНИЦИ И СТУДЕНТИ: ДИФЕРЕНЦИАЛНО СМЯТАНЕ

Б. В. Тошев Българско дружество за химическо образование и история и философия на химията

ВАСИЛ ХРИСТОВ БОЗАРОВ

Пенка Бозарова, Здравка Костова

БИБЛИОГРАФИЯ НА СТАТИИ ЗА МИСКОНЦЕПЦИИТЕ В ОБУЧЕНИЕТО ПО ПРИРОДНИ НАУКИ ВЪВ ВСИЧКИ ОБРАЗОВАТЕЛНИ НИВА

Б. В. Тошев Българско дружество за химическо образование и история и философия на химията

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SCIENTIX – OБЩНОСТ ЗА НАУЧНО ОБРАЗОВАНИЕ В ЕВРОПА

Свежина Димитрова Народна астрономическа обсерватория и планетариум „Николай Коперник“ – Варна

BOTYU ATANASSOV BOTEV

Zdravka Kostova, Margarita Topashka-Ancheva

CHRONOLOGY OF CHEMICAL ELEMENTS DISCOVERIES

Maria Atanassova, Radoslav Angelov

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ОБРАЗОВАНИЕ ЗА ПРИРОДОНАУЧНА ГРАМОТНОСТ

Адриана Тафрова-Григорова

A COMMENTARY ON THE GENERATION OF AUDIENCE-ORIENTED EDUCATIONAL PARADIGMS IN NUCLEAR PHYSICS

Baldomero Herrera-González Universidad Autónoma del Estado de México, Mexico

2013 година
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DIFFERENTIAL TEACHING IN SCHOOL SCIENCE EDUCATION: CONCEPTUAL PRINCIPLES

G. Yuzbasheva Kherson Academy of Continuing Education, Ukraine

АНАЛИЗ НА ПОСТИЖЕНИЯТА НА УЧЕНИЦИТЕ ОТ ШЕСТИ КЛАС ВЪРХУ РАЗДЕЛ „ВЕЩЕСТВА И ТЕХНИТЕ СВОЙСТВА“ ПО „ЧОВЕКЪТ И ПРИРОДАТА“

Иваничка Буровска, Стефан Цаковски Регионален инспекторат по образованието – Ловеч

HISTORY AND PHILOSOPHY OF SCIENCE: SOME RECENT PERIODICALS (2013)

Chemistry: Bulgarian Journal of Science Education

45. НАЦИОНАЛНА КОНФЕРЕНЦИЯ НА УЧИТЕЛИТЕ ПО ХИМИЯ

„Образователни стандарти и природонаучна грамотност“ – това е темата на състоялата се от 25 до 27 октомври 2013 г. в Габрово 45. Национална конфе- ренция на учителите по химия с международно участие, която по традиция се проведе комбинирано с Годишната конференция на Българското дружество за химическо образование и история и философия на химията. Изборът на темата е предизвикан от факта, че развиването на природонаучна грамотност е обща тенденция на реформите на учебните програми и главна

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ЗА ХИМИЯТА НА БИРАТА

Ивелин Кулев

МЕТЕОРИТЪТ ОТ БЕЛОГРАДЧИК

Б. В. Тошев Българско дружество за химическо образование и история и философия на химията

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RECASTING THE DERIVATION OF THE CLAPEYRON EQUATION INTO A CONCEPTUALLY SIMPLER FORM

Srihari Murthy Meenakshi Sundararajan Engineering College, India

CHEMICAL REACTIONS DO NOT ALWAYS MODERATE CHANGES IN CONCENTRATION OF AN ACTIVE COMPONENT

Joan J. Solaz-Portolés, Vicent Sanjosé Universitat de Valènciа, Spain

POLYMETALLIC COMPEXES: CV. SYNTHESIS, SPECTRAL, THERMOGRAVIMETRIC, XRD, MOLECULAR MODELLING AND POTENTIAL ANTIBACTERIAL PROPERTIES OF TETRAMERIC COMPLEXES OF Co(II), Ni(II), Cu(II), Zn(II), Cd(II) AND Hg(II) WITH OCTADENTATE AZODYE LIGANDS

Bipin B. Mahapatra, S. N. Dehury, A. K. Sarangi, S. N. Chaulia G. M. Autonomous College, India Covt. College of Engineering Kalahandi, India DAV Junior College, India

ПРОФЕСОР ЕЛЕНА КИРКОВА НАВЪРШИ 90 ГОДИНИ

CELEBRATING 90TH ANNIVERSARY OF PROFESSOR ELENA KIRKOVA

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SIMULATION OF THE FATTY ACID SYNTHASE COMPLEX MECHANISM OF ACTION

M.E.A. Mohammed, Ali Abeer, Fatima Elsamani, O.M. Elsheikh, Abdulrizak Hodow, O. Khamis Haji

FORMING OF CONTENT OF DIFFERENTIAL TEACHING OF CHEMISTRY IN SCHOOL EDUCATION OF UKRAINE

G. Yuzbasheva Kherson Academy of Continuing Education, Ukraine

ИЗСЛЕДВАНЕ НА РАДИКАЛ-УЛАВЯЩА СПОСОБНОСТ

Станислав Станимиров, Живко Велков

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COLORFUL EXPERIMENTS FOR STUDENTS: SYNTHESIS OF INDIGO AND DERIVATIVES

Vanessa BIANDA, Jos-Antonio CONSTENLA, Rolf HAUBRICHS, Pierre-Lonard ZAFFALON

OBSERVING CHANGE IN POTASSIUM ABUNDANCE IN A SOIL EROSION EXPERIMENT WITH FIELD INFRARED SPECTROSCOPY

Mila Ivanova Luleva, Harald van der Werff, Freek van der Meer, Victor Jetten

ЦАРСКАТА ПЕЩЕРА

Рафаил ПОПОВ

УЧИЛИЩНИ ЛАБОРАТОРИИ И ОБОРУДВАНЕ SCHOOL LABORATORIES AND EQUIPMENT

Учебни лаборатории Илюстрации от каталог на Franz Hugershoff, Лайциг, притежаван от бъдещия

2012 година
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ADDRESING STUDENTS’ MISCONCEPTIONS CONCERNING CHEMICAL REACTIONS AND SYMBOLIC REPRESENTATIONS

Marina I. Stojanovska, Vladimir M. Petruševski, Bojan T. Šoptrajanov

АНАЛИЗ НА ПОСТИЖЕНИЯТА НА УЧЕНИЦИТЕ ОТ ПЕТИ КЛАС ВЪРХУ РАЗДЕЛ „ВЕЩЕСТВА И ТЕХНИТЕ СВОЙСТВА“ ПО ЧОВЕКЪТ И ПРИРОДАТА

Иваничка Буровска, Стефан Цаковски Регионален инспекторат по образованието – Ловеч

ЕКОТОКСИКОЛОГИЯ

Васил Симеонов

ПРОФ. МЕДОДИЙ ПОПОВ ЗА НАУКАТА И НАУЧНАТА ДЕЙНОСТ (1920 Г.)

Проф. Методий Попов (1881-1954) Госпожици и Господа студенти,

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КОНЦЕПТУАЛНА СХЕМА НА УЧИЛИЩНИЯ КУРС П О ХИМИЯ – МАКР О СКОПСКИ ПОДХОД

Б. В. Тошев Българско дружество за химическо образование и история и философия на химията

ROLE OF ULTRASONIC WAVES TO STUDY MOLECULAR INTERACTIONS IN AQUEOUS SOLUTION OF DICLOFENAC SODIUM

Sunanda S. Aswale, Shashikant R. Aswale, Aparna B. Dhote Lokmanya Tilak Mahavidyalaya, INDIA Nilkanthrao Shinde College, INDIA

SIMULTANEOUS ESTIMATION OF IBUPROFEN AND RANITIDINE HYDROCHLORIDE USING UV SPECTROPHOT O METRIC METHOD

Jadupati Malakar, Amit Kumar Nayak Bengal College of Pharmaceutical Sciences and Research, INDIA

GAPS AND OPPORTUNITIES IN THE USE OF REMOTE SENSING FOR SOIL EROSION ASSESSMENT

Mila Ivanova Luleva, Harald van der Werff, Freek van der Meer, Victor Jetten

РАДИОХИМИЯ И АРХЕОМЕТРИЯ: ПРО Ф. ДХН ИВЕЛИН КУЛЕВ RADIOCHEMISTRY AND ARCHEOMETRY: PROF. IVELIN KULEFF, DSc

Б. В. Тошев Българско дружество за химическо образование и история и философия на химията

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TEACHING THE CONSTITUTION OF MATTER

Małgorzata Nodzyńska, Jan Rajmund Paśko

СЪСИРВАЩА СИСТЕМА НА КРЪВТА

Маша Радославова, Ася Драгоева

CATALITIC VOLCANO

CATALITIC VOLCANO

43-ТА МЕЖДУНАРОДНА ОЛИМПИАДА ПО ХИМИЯ

Донка ТАШЕВА, Пенка ЦАНОВА

ЮБИЛЕЙ: ПРОФ. ДХН БОРИС ГЪЛЪБОВ JUBILEE: PROF. DR. BORIS GALABOV

Б. В. Тошев Българско дружество за химическо образование и история и философия на химията

ПЪРВИЯТ ПРАВИЛНИК ЗА УЧЕБНИЦИТЕ (1897 Г.)

Чл. 1. Съставянето и издаване на учебници се предоставя на частната инициа- тива. Забележка: На учителите – съставители на учебници се запрещава сами да разпродават своите учебници. Чл. 2. Министерството на народното просвещение може да определя премии по конкурс за съставяне на учебници за горните класове на гимназиите и специ- алните училища. Чл. 3. Никой учебник не може да бъде въведен в училищата, ако предварително не е прегледан и одобрен от Министерството на народното просвещение. Чл.

JOHN DEWEY: HOW WE THINK (1910)

John Dewey (1859 – 1952)

ИНФОРМАЦИЯ ЗА СПЕЦИАЛНОСТИТЕ В ОБЛАСТТА НА ПРИРОДНИТЕ НАУКИ В СОФИЙСКИЯ УНИВЕРСИТЕТ „СВ. КЛИМЕНТ ОХРИДСКИ“ БИОЛОГИЧЕСКИ ФАКУЛТЕТ

1. Биология Студентите от специалност Биология придобиват знания и практически умения в областта на биологическите науки, като акцентът е поставен на организмово равнище. Те се подготвят да изследват биологията на организмите на клетъчно- организмово, популационно и екосистемно ниво в научно-функционален и прило- жен аспект, с оглед на провеждане на научно-изследователска, научно-приложна, производствена и педагогическа дейност. Чрез широк набор избираеми и факул- тативни курсове студентите

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УЧИТЕЛИТЕ ПО ПРИРОДНИ НАУКИ – ЗА КОНСТРУКТИВИСТКАТА УЧЕБНА СРЕДА В БЪЛГАРСКОТО УЧИЛИЩЕ

Адриана Тафрова-Григорова, Милена Кирова, Елена Бояджиева

ПОВИШАВАНЕ ИНТЕРЕСА КЪМ ИСТОРИЯТА НА ХИМИЧНИТЕ ЗНАНИЯ И ПРАКТИКИ ПО БЪЛГАРСКИТЕ ЗЕМИ

Людмила Генкова, Свобода Бенева Българско дружество за химическо образование и история и философия на химията

НАЧАЛО НА ПРЕПОДАВАНЕТО НА УЧЕБЕН ПРЕДМЕТ ХИМИЯ В АПРИЛОВОТО УЧИЛИЩЕ В ГАБРОВО

Мария Николова Национална Априловска гимназия – Габрово

ПРИРОДОНАУЧНОТО ОБРАЗОВАНИЕ В БЪЛГАРИЯ – ФОТОАРХИВ

В един дълъг период от време гимназиалните учители по математика, физика, химия и естествена

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„МАГИЯТА НА ХИМИЯТА“ – ВЕЧЕР НА ХИМИЯТА В ЕЗИКОВА ГИМНАЗИЯ „АКАД. Л. СТОЯНОВ“ БЛАГОЕВГРАД

Стефка Михайлова Езикова гимназия „Акад. Людмил Стоянов“ – Благоевград

МЕЖДУНАРОДНАТА ГОДИНА НА ХИМИЯТА 2011 В ПОЩЕНСКИ МАРКИ

Б. В. Тошев Българско дружество за химическо образование и история и философия на химията

ЗА ПРИРОДНИТЕ НАУКИ И ЗА ПРАКТИКУМА ПО ФИЗИКА (Иванов, 1926)

Бурният развой на естествознанието във всичките му клонове през XIX –ия век предизвика дълбоки промени в мирогледа на културния свят, в техниката и в индустрията, в социалните отношения и в държавните интереси. Можем ли днес да си представим един философ, един държавен мъж, един обществен деец, един индустриалец, просто един културен човек, който би могъл да игнорира придобив- ките на природните науки през последния век. Какви ужасни катастрофи, какви социални сътресения би сполетяло съвре

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MURPHY’S LAW IN CHEMISTRY

Milan D. Stojković

42-рa МЕЖДУНАРОДНА ОЛИМПИАДА ПО ХИМИЯ

Донка Ташева, Пенка Цанова

СЕМЕЙНИ УЧЕНИЧЕСКИ ВЕЧЕРИНКИ

Семейството трябва да познава училишето и училишето трябва да познава семейството. Взаимното познанство се налага от обстоятелството, че те, макар и да са два различни по природата си фактори на възпитанието, преследват една и съща проста цел – младото поколение да бъде по-умно, по-нравствено, физически по-здраво и по-щастливо от старото – децата да бъдат по-щастливи от родителите