Abstrak. Sifat inhibitor korosi senyawa turunan thiaamida-pirazolindol (TP) telah dikaji menggunakan teori fungsional kerapatan pada tingkatan teori B3LYP/6-31G(d). Pengaruh gugus substitusi pendonor dan penarik elektron (NH2, SH, CHCH2, CH3, OH, CHO, COOH, F, NO2) terhadap efisiensi anti korosi senyawa thiaamidapirazolindol juga dihitung. Parameter kuantum untuk senyawa anti korosi seperti energi orbital (EHOMO dan ELUMO), potensial ionisasi (I), afinitas elektron (A) dan elektronegativitas (χ) memiliki hubungan yang linier dengan efisiensi anti korosi (IE%) senyawa turunan thiaamida-pirazolindol. Gugus pendonor elektron meningkatkan nilai IE%. Urutan kenaikan IE% adalah NO2 < CHO < COOH < F < CHCH2 < OH < CH3 < NH2. Penambahan gugus pendonor elektron amina (NH2) meningkatkan IE% hingga 98,76 % dibandingkan IE% thiaamida-pirazolindol murni 90,80 %. Penambahan gugus penarik elektron menurunkan IE% hingga mencapai 82,82 %. Kajian teoritis ini akan berkontribusi besar dalam mendesain dan sintesis senyawa inhibitor organik dengan efisiensi inhibitor tinggi.Kata kunci: inhibitor korosi, teori fungsional kerapatan, thiaamida-pirazolindol Abstract. Corrosion inhibitor properties of thiamide pyrazolindole and its derivatives has been elucidated by means of density functional theory (DFT) at B3LYP/6-31G(d) level of theory. Effect of electron donating and withdrawing groups such as NH2, SH, CHCH2, CH3, OH, CHO, COOH, F and NO2 on the corrosion inhibitor of thiamide pyrazolindole derivatives also have been studied. The quantum chemical parameters such as the frontier orbital energies (EHOMO), ionization potential (I), electron affinity (A) and electronegativity (χ) are closely related to the corrosion inhibition efficiency (IE%) of thiamide pyrazolindole derivatives. The presence of electron donating groups increases IE% values meanwhile electron withdrawing groups reduce IE% values. The enhancement of IE% follows NO2 < CHO < COOH < SH < F < CH3 < CHCH2 < OH < NH2. Electron donating NH2 group gives 98,76 % of IE%, pure thiamide pyrazolindol IE% = 90,80 %. In contrast, electron withdrawing NO2 group gives IE% only 82,82 %. This theoretical study would have a significant contribution in designing high-efficiency organic corrosion inhibitors.
This study aims to evaluate an electronic student worksheets product based on discovery learning that valid and reliable on thermochemical topic. The development of electronic student worksheets-based on discovery learning follows the steps of the 4D development model, namely define, design, develop, disseminate. The feasibility test of the developed learning device was analyzed using a validation sheet. The assessment of the feasibility of the learning tools developed was carried out by three expert validators who are competent in the field of education at the University of Mataram. Criticisms and suggestions given by the validator are used as improvements to the developed electronic student worksheets. Data analysis was carried out using descriptive percentage techniques, Aiken's V index, and percentage of agreement. The validation results show that the developed electronic student worksheets component is included in the valid category with an average validity value of 0.79. The results of the agreement between validators showed that the developed electronic student worksheetshad a percentage of more than 75% which was included in the reliable category. Based on the results of the validation and reliability tests, the electronic student worksheets based on discovery learning developed can be concluded to be valid and reliable. A more complete and detailed explanation of the development of electronic student worksheets based on discovery learning and validation results is presented in this article.
The goal of this study is to create an E-worksheet product based on discovery learning that will help students improve their decision-making skills and scientific attitudes. This E-worksheet was created using the 4D development methodology, which includes the processes of define, design, develop, and disseminate. Students in class XI science SMAN 6 Mataram served as test subjects for this study. The limited trial is taught in one lesson, while the wide trial is taught in two classes. The ANCOVA test, descriptive percentage techniques, and percentage of agreement were used to analyze the data. The practicality data analysis revealed that teachers and students responded with a percentage of 80 and 86.42 percent, respectively, showing that the E-worksheet evolved in the practical category. The results of the effectiveness test using the ANCOVA test obtained Fcount > Ftable (8.28 > 3.98) on decision-making skills and Fcount > Ftable (6.94 > 3.98) on scientific attitude with a significant level of 5%. The null hypothesis (H0) is rejected, which means that E-worksheet influences discovery learning to improve students' decision-making skills and scientific attitudes in grade-eleventh science students. The E-worksheet based on discovery learning is practical and successful for enhancing students' decision-making skills and scientific attitudes toward grade-eleventh science students, according to the research objectives and findings.
Limited laboratory facilities are an important factor causing the low quality of chemistry learning. Therefore, the necessity to develop innovative media is evitable, in particular in the form of simple practical tools made from materials that are easily found in everyday life. If the quality of learning can be improved, then it may encourage students' interest in learning in chemistry. This article reports on the development of an instrument (questionnaire) of students' interest in chemistry lessons at school. The development begins with an analysis of the factors that influence interest in learning from the available literature; and the analysis resulted in 4 (four) indicators of interest, namely (1) happy feeling, (2) interest in performance, (3) attention, and (4) involvement. These four indicators then were developed into relevant questionnaire statements to determine students' perceptions of chemistry learning at school. To test the validity of the contents of the questionnaire, expert validation was carried out by 3 experts in the field of educational psychology. The results of expert validation were then analyzed with the Aiken V formula after previously converting the data into interval data. The results of the analysis show that the value of V ranges from 0.72 to 0.82 which means in the good category for all indicators of interest. In conclusion the student learning interest questionnaire is feasible and ready to be used to determine the effect of innovative learning on student learning interest.
Abstrak : Tujuan dari penelitian ini adalah untuk mengetahui: (1) pengaruh model implementasi jembatan analogis pada pemahaman mikroskopis siswa, (2) pengaruh gaya belajar siswa pada pemahaman mikroskopis siswa, dan (3) interaksi model Bridge analogis dan siswa gaya belajar terhadap pemahaman mikroskopis siswa. Ini adalah studi eksperimental semu dengan non setara pre-test post-test desain kelompok kontrol dan 2 x 3 desain analisis faktorial. Populasi penelitian ini adalah 206 siswa dari XI IPA di SMAN 2 Praya didistribusikan dalam empat kelompok belajar. Dua kelompok alami utuh dengan kemampuan setara sebelum terpilih sebagai sampel. Mereka dipilih secara acak sebagai kelompok eksperimen dan kelompok kontrol, maka XI IPA 4 didefinisikan sebagai kelompok eksperimen (perlakuan model Bridge analogis) dan XI IPA 3 didefinisikan sebagai kelompok kontrol (diobati dengan model konvensional). Instrumen penelitian ini adalah mikroskopis pemahaman siswa tes dan angket gaya belajar siswa. Data pemahaman mikroskopis siswa dikumpulkan dari skor tes siswa sedangkan data tentang gaya belajar siswa yang dikumpulkan dari kuesioner. Analisis data menggunakan analisis kovariannya (ANCOVA) dengan pre-test skor sebagai kovariannya. Semua data diasumsikan normal, linier dan homogen. Beda Nyata Terkecil (LSD) digunakan sebagai analisis Post. Analisis statistik menunjukkan bahwa model Bridge Analogical tidak berpengaruh secara signifikan terhadap pemahaman mikroskopis siswa (p> 0,05). Gaya belajar siswa, namun secara signifikan mempengaruhi pemahaman mikroskopis siswa (p <0,05). Interaksi model Bridge analogis dan gaya belajar yang secara signifikan mempengaruhi pemahaman mikroskopis siswa (p <0,05). Analisis post menunjukkan bahwa model Bridge Analogical paling baik diterapkan pada kelompok mahasiswa belajar gaya visual. Kata kunci: representasi mikroskopis, analogi; gaya belajarAbstract : The aims of this study are to find out: (1) the influence of Analogical Bridge model implementation on student's microscopic comprehension; (2) the influence of student's learning style on student's microscopic comprehension; and (3) the interaction of Analogical Bridge model and student's learning style on student's microscopic comprehension. It is a quasy experimental study with non equivalent pre-test post-test control group design and 2 x 3 factorial analysis design. The population of this study are 206 students of the XI IPA in SMAN 2 Praya distributed in four study group. Two naturally intact group with equivalent prior abilities are selected as the sample. They are randomly selected as experimental group and control group, then XI IPA 4 is defined as an experimental group (treated by Analogical Bridge model) and XI IPA 3 is defined as a control group (treated by conventional model). Instruments of this study are student's microscopic comprehension test and student's learning style questionnaire. Data of student's microscopic comprehension are collected from student's test score while data about student's learning style are collected from que...
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