Exploring the relationships among stoichiometric coefficients, number of transferred electrons, mean oxidation number of carbons, and oxidative ratio in organic combustion reactions

Combustion reactions, stoichiometry, and redox reactions are some of the basic contents in chemistry curriculum. Although the counting of transferred electrons is critical in redox reactions, assigning mean oxidation number of organic carbons (ONc) is not always easy. Even though the relationship between the oxidative ratio (OR) and ONc is known, the relationship between the number of transferred electrons (Te−) and OR has not been thoroughly studied. The H-atom method has already been developed to balance and deduct organic combustion reactions. It can be used further to help establish the relationships among the stoichiometric coefficients (SC), the number of transferred hydrogens (TH), and Te−. This article uses the procedures of the H-atom method for balancing and deducting, and the known relationships among SC, TH, and Te− for exploring the relationships among SC, Te−, ONc, and OR in organic combustion reactions. By integrating three sets of relationships: (i) SC and Te−, (ii) Te− and ON, and (iii) SC and OR, the interconversions among SC, Te−, ONc, and OR can be mathematically formulated. Furthermore, Te−, ONc, and OR can be assigned by SC and the general molecular formula of CxHyOzXw.

Difficult Topics in the Chemistry Curriculum – Bulgarian Students‘ View

Chemistry is often considered a difficult subject, and the way students perceive learning affects their achievements. The research aims to identify: the topics in the secondary Chemistry curriculum perceived as difficult and as interesting by the Bulgarian students, the reasons for students’ difficulties and ways to overcome it. An inquiry was conducted with 321 students aged 16 – 17 years. According to them, the most difficult topics are Organic Chemistry and Chemical calculations (abstract and requiring specific skills). The most interesting topics are Organic Chemistry and Theory of Electrolytic Dissociation. Acids and bases. There is no significant correlation between levels of perceived difficulty and interest. Students relate difficulties to: information overload, emphasis on memorization, and lack of connections to everyday life. More lab activities and the practical application of the knowledge are recommended. Our research results can help improve Chemistry curricula and teaching practice.

The Potential of Clitoria ternatea L. Extracts as an Alternative Indicator in Acid-Base Titration

Experiments are an important part of the chemistry curriculum. An indicator in the form of a synthesis indicator is commonly used in acid-base materials experiments. The usage of synthetic indicators can result in waste that is both environmentally harmful and costly. The butterfly pea flower is one of the plants that contains anthocyanins, which have the potential to be used as an alternative indication of natural acids and bases. The study aims to determine the acid and base material curriculum and competency indicators, as well as the potential of butterfly pea flower extract as a substitute for synthesis indicators and the practicality of butterfly pea flower extract as a chemical experimental design in SMA/MA. This study employs a descriptive qualitative research method that includes literature review, observation, experimentation, and interviewing. The results showed that the relationship between acid-base materials and experiments was the determination of natural materials as acid-base indicators, the pH of the solution, the identification of acid-base properties, and acid-base titration. The butterfly pea flower indicator was produced from maceration extraction using 96% ethanol as the solvent. The butterfly pea flower indicator gives pink color at pH 1-2, reddish purple at pH 3, light purple at pH 4-5, turquoise at pH 6, bluish green at pH 7, light blue at pH 8-9, green at pH 10, yellowish green at pH 11, greenish yellow at pH 12-13, and yellow at pH 14. The titration step showed that butterfly pea flower indicators could replace synthetic indicators, namely phenolphthalein and methyl orange. Based on the analysis, the butterfly pea flower indicator can be used as an alternative indicator in acid base titration and an alternative experimental design in schools.

A new spin on electrochemistry in the undergraduate lab

The growing interest in electrochemistry over recent years has sparked an increase in the popularity of various electrochemical techniques, including more advanced methods, that have previously been overlooked in academia and industry. This makes comprehensive hands-on experience in electrochemistry a highly demanded addition to chemistry graduates. However, many students do not receive sufficient training in the theory and experimental design to confidently use and apply various electrochemical techniques throughout their undergraduate, and sometimes even in graduate studies. Here we summarize the theory and practical applications for both rotating disk electrode (RDE) and rotating ring disk electrode (RRDE) techniques. The different modes of operation of rotating ring disk voltammetry, methodologies of data analysis and interpretation as well as the scope of the information that can be extracted from the RDE/RRDE are discussed. Proposed modifications of the laboratory curriculum will allow students to examine and learn valuable information about the reactions on the surface of the electrode/liquid interface. This information will allow chemists to confidently use RDE and RRDE techniques for a wide range of research and development targets. Furthermore, incorporating these techniques into existing chemistry laboratories will help chemistry educators to enrich the undergraduate chemistry curriculum and improve students’ learning outcomes.

The Recontruction Of Chemistry Curriculum Elements Of Vocational School For Nursing Skills Study Programs

Chemical teaching materials don’t support the learning of nursing vocational competencies, so it is necessary to analyze the suitability of chemical content with nursing vocational content. This research aims to reconstruct elements of the chemical curriculum relevant to the competence of nursing vocational schools. The research design used is Developmental Research with the stages of design, development, and evaluation. The research was conducted at SMK Nusa Bhakti Bandung and SMKN 1 Koto Besar (Dharmasraya Regency). The study involved two chemistry education experts, six nursing vocational teachers, and six chemistry teachers in nursing. The research instruments used are formulation formats in the form of KD, chemical content, knowledge dimensions, learning strategies, and learning evaluations that have been validated. The data of the research results was analyzed in a qualitative descriptive way then used as input for product improvement. The results showed that design of KD, chemical content, knowledge dimensions, learning strategies, and learning evaluation developed have good relevance to the demands of nursing vocational competencies. Viewed from the validation of teachers in nursing vocational schools obtained good validation results.

Reconstruction of Chemistry Curriculum Elements of Vocational School (SMK) of Mechanical Engineering Study Program

To support the productive subject of expertise field, chemistry curriculum elements and materials in SMK need to be reconstructed. This study aims to produce an integrated chemistry syllabus of Mechanical Engineering in SMK. This study uses a development research method with research subjects: 2 chemistry education experts, 6 chemistry teachers, 4 productive teachers and 2 vice curriculum principals at SMKN Bandung. The results show the relevant chemistry KD to the Mechanical Engineering KD includes knowledge and skill competencies: explaining, describing, applying, determining, identifying, classifying, analyzing, constructing, proposing ideas, designing and conducting experiments. The compositions of chemical content that is relevant are types, physical and chemical properties, symbols, roles, handling of hazardous chemicals, and standard chemical safety and security in the work environment (5.9%), redox reactions (11, 8%), electrochemistry (11.8%), thermochemistry (11.8%), physical and chemical properties of metals, pure metals and alloys (11.8%), electron configurations and the periodic system (5.9%), bonding chemical (5.9%), corrosion (5.9%), metallurgy (5.9%), hydrocarbons (5.9%), petroleum (5.9%), polymers (5.9%), and reaction rate affecting factors (5.9%). The learning strategy is a scientific approach of discovery learning, project-based learning, problem-based learning, and guided inquiry. The evaluation results are the competence of knowledge, skills and attitudes assessment.