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This study aims to explore the perspectives of gifted students on augmented reality, one of the innovative possibilities offered by instructional technologies. Action research involved 40 gifted students aged 10-11, enrolled in a Science and Art Center (SAC). Over the course of five weeks, the study focused on teaching various topics related to chemistry, including the structure of atoms, the symbols and applications of elements and compounds, as well as the formation of different compounds and their relevance to everyday life. Augmented reality (AR) applications were utilized for instructional purposes. The findings revealed that the AR applications employed during the study facilitated learning, heightened interest, and curiosity in the subject matter, enhanced the enjoyment and productivity of the lessons, provided a tangible understanding through their three-dimensional representations appealing to multiple senses, and offered a sense of realism by enabling students to interact with virtual objects in real-time. [ABSTRACT FROM AUTHOR]

With a growing number of PCMs and new, suitable PCM candidates, an overview is not only important, but also increasingly complex. Classification of PCM was thus changed significantly in the past decades. A review of classification of PCMs from recent years shows that not only different classification criteria are used, but more important that they are often mixed, used inconsistently, even without a clear goal. Focusing on the main goal of current classification schemes, to give an overview of the material options for the search for new, suitable PCM candidates, including already established PCMs, a consistent classification is developed in a desktop study. For this, first, the general options for classification criteria are reviewed, and then the appropriate ones selected. Then, based on them a new, revised PCM classification is suggested. It is specifically detailed with regard to mixtures; for binary mixtures it is based on a literature review performed within the study. The result also stresses the importance of specific R&D: for pure substances the sources and the chemical modification, and for mixtures their optimization by new compositions, additives, etc. [ABSTRACT FROM AUTHOR]

With a growing number of PCMs and new, suitable PCM candidates, an overview is not only important, but also increasingly complex. Classification of PCM was thus changed significantly in the past decades. A review of classification of PCMs from recent years shows that not only different classification criteria are used, but more important that they are often mixed, used inconsistently, even without a clear goal. Focusing on the main goal of current classification schemes, to give an overview of the material options for the search for new, suitable PCM candidates, including already established PCMs, a consistent classification is developed in a desktop study. For this, first, the general options for classification criteria are reviewed, and then the appropriate ones selected. Then, based on them a new, revised PCM classification is suggested. It is specifically detailed with regard to mixtures; for binary mixtures it is based on a literature review performed within the study. The result also stresses the importance of specific R&D: for pure substances the sources and the chemical modification, and for mixtures their optimization by new compositions, additives, etc.

Students’ misconceptions in science can lead to a range of learning difficulties if the teacher does not choose the appropriate teaching strategies to reduce their frequency. In this paper, 13–14-year-old students’ misconceptions regarding structure and states of matter, pure substances, and mixtures are explored. The teaching strategy with E-learning material was applied to examine its effects on the frequency of misconceptions. The research was conducted in urban schools in Bosnia and Herzegovina with 7th- and 8th-grade students. Findings pointed to the misconceptions originating in transferring the macroscopic observations into the submicroscopic level and in misinterpretation of the size of particles. Students who used E-learning material at school mostly had lower percentages of misconceptions in comparison to students from the control group and students who accessed the same E-learning material from their home. This indicates that the E-learning strategy could have promising results if applied more extensively at schools. This study aims to direct teachers’ attention toward applying E-learning in chemistry teaching, for students to gain scientifically accepted knowledge and to reduce the occurrence of misconceptions.

The most challenging problems in the field of chemico- and bioanalytical measurements are described. These problems are being solved, in particular, by participating in new international comparisons organized by the Consultative Committee for Amount of Substance: Metrology in Chemistry and Biology of the International Committee of Weights and Measures (CCQM CIPM). Solutions of these challenging problems are presented. The objectives and tasks of developing key comparisons in the following areas are described: isotopic measurements; determination of the purity of substances; organic analysis; bioanalytical measurements; measurements of aerosol particle parameters; measurements in the field of gas analysis and electrochemistry. It is shown that participation in international key comparisons allows obtaining valid and reliable results of measurements of the composition and properties of gas and liquid media, as well as solid substances and materials. [ABSTRACT FROM AUTHOR]

The predictive error in vapor pressure of limited-data Wagner constants relative to that of entire-curve constants is studied for eleven data intervals. Good precision is assumed for data inputs, four digits in the mantissa of Ln Pv,r and five digits for Tr. An algebraic solution for the fully-determined case based on only four data points is used to estimate Wagner constants. Seventy-two species are used to assess the impact of the location of the two interior points and the location and width of the limited-data interval upon the error in predicted Pv,r due to data imprecision. Hydrogen, helium, R152a, and water are used to assess error due to Wagner imperfection and compare predictive capability of the algebraic fully-determined and regressed over-determined approaches. The results indicate that limited VLE data of good precision from reduced temperature intervals with a width = 0.1 and a lower bound = 0.6 can generally provide reasonable VLE predictions over the entire two-phase curve for pure substances, with average error of approximately 1%. It is shown that the algebraic, fully-determined solution presented is a viable tool for investigating the extensibility of limited-data Wagner constants. [ABSTRACT FROM AUTHOR]

The heat of vaporization of a pure substance at its normal boiling temperature is a very important property in many chemical processes. In this work, a new empirical method was developed to predict vaporization enthalpy of pure substances. This equation is a function of normal boiling temperature, critical temperature, and critical pressure. The presented model is simple to use and provides an improvement over the existing equations for 452 pure substances in wide boiling range. The results showed that the proposed correlation is more accurate than the literature methods for pure substances in a wide boiling range (20.3–722 K).

The problem of water determination in the creation of pure substances and new functional materials with a low moisture content is considered. The structure, metrological characteristics, and prospects of application of the state primary standard of mass fraction and mass (molar) concentration of water in solid and liquid substances and materials GET 173-2013 are presented. Examples of developing thermogravimetric and chemical analyses are provided. [ABSTRACT FROM AUTHOR]

• A thermal conductivity model is developed based on the analogy concept and is applied to pure substances. • Data are included for 24 organic families and 56 functional groups in a temperature range of 16.6 to 604.65 K and pressures below 4032 bar. • The final model presents one interaction parameter that is generalized using the group contribution technique. • Prediction of thermal conductivity in the saturation and single-phase conditions are done. • The model provides acceptable results when in comparison to other correlations. The aim of this work is to apply a group contribution method to describe the thermal conductivity of pure substances. The model has five adjustable parameters that have been generalized using the acentric factor, RT c /P c relation, and a contribution of each group in the substance through a tendency graphical analysis. The thermodynamical properties included in the model are estimated using a modified Peng-Robinson EoS. The proposed model is applied to 351 substances distributed into 160 for the correlation, 96 for testing, and 95 for predictive capabilities. The above includes 24 organic families and 56 functional groups. The average absolute deviations are below 6.51% for the liquid-vapor coexistence and below 7.93% for the one-phase condition. The overall results are compared to other literature works on saturation and single-phase conditions. These results show that the model provides acceptable values of deviations and can be used to describe different types of substances. Finally, three cases of study are done as an alternative to represent the alkanes, 1-alcohols, and water substances. The average absolute deviations for 1-alkanes and 1-alcohols are below 7.00% and for water is around 3.76%. In general, the generalized model can be used as an alternative to describe the thermal conductivities of pure substances in the saturation and single-phase conditions with acceptable results. A group contribution method to model the thermal conductivity of pure substances. Luis F. Cardona, Luis A. Forero and Jorge A. Velásquez. [Display omitted] [ABSTRACT FROM AUTHOR]

Abstract: The heat of vaporization of a pure substance at its normal boiling temperature is a very important property in many chemical processes. In this work, a new empirical method was developed to predict vaporization enthalpy of pure substances. This equation is a function of normal boiling temperature, critical temperature, and critical pressure. The presented model is simple to use and provides an improvement over the existing equations for 452 pure substances in wide boiling range. The results showed that the proposed correlation is more accurate than the literature methods for pure substances in a wide boiling range (20.3–722K). [Copyright &y& Elsevier]

Highlights: [•] Vapor pressure of 75 pure substances was modeled by a new accurate method. [•] Model was compared with five mostly used equations include Antoine and Wagner model. [•] Results showed that new model is more accurate than other models with 0.091% AARD. [Copyright &y& Elsevier]

Abstract: A simple equation is presented for predicting the temperature dependence of the vapor-pressure of a pure substance along the entire (liquid+vapor) coexistence curve, from the triple point to the critical point. The proposed equation is based on the use of a dimensionless temperature reduced by using critical and triple point values, and of the Clausius–Clapeyron equation as a zeroth-order approximation. The pressure and temperature at the triple point, the normal boiling temperature, and the pressure and temperature at the critical point are required as input data. The proposed equation is verified for 53 fluids by using NIST data. These data are reproduced with an overall average deviation of 0.55%. [Copyright &y& Elsevier]

Abstract: We use the Clausius–Clapeyron equation to calculate third virial coefficients at low reduced temperatures. This procedure gives an alternative to predict third virial coefficients in a region where the third virial coefficient is difficult to measure. We compare the results of this method with published third virial coefficient data. Calculated third virial coefficients have average percentage deviations within 5% of the experimental values at reduced temperatures between 0.8 and 1.0. [Copyright &y& Elsevier]