Kinetics of Complex Reaction of Eugenol Hydrogenation to 2-Methoxy-4-Propylphenol in Pd/Y Catalyst

Eugenol and isoeugenol hydrogenations using Pt, Pd, Ni as a single or combined metal, that was supported on X and Y zeolite have been carried out. The experiment result showed that in hydrogenation reaction using metal that was supported on zeolite, eugenol is more easily hydrogenated than isoeugenol. Pd metal that was supported on Y zeolite as a catalyst in eugenol hydrogenation is more effective than Ni, Pt or combined metal (Pt,Pd,Ni/X). The highest conversion selectivity of eugenol hydrogenation is in 6% catalyst of Pd (10%)/Y that produced 98.24% of 2-methoxy-4- propylphenol. Kinetic of reaction is very important data that is needed in processing for industry scale, because kinetic can show how fast the starting material is converted into products. In this research, kinetic of the reaction was done by eugenol hydrogenation at 245oC with variation of time using Pd/Y catalyst. The result shows that eugenol hydrogenation is a complex reaction, because the reaction yields not only 2-methoxy-4-propylphenol as a main product, but also cis-isoeugenol and trans-isoeugenol as the side products. The reaction pathway of eugenol hydrogenation in Pd/Y catalyst is a combination of parallel and consecutive pathway and pseudo first order reaction with k = 0.5509

PENGEMBANGAN BAHAN AJAR KIMIA DASAR BERBASIS CONCEPTUAL CHANGE TEXT PADA MATERI REDOKS

DEVELOPMENT OF TEACHING MATERIALS BASED ON CONCEPTUAL CHANGE TEXT ON REDOX MATERIALS FOR BASIC CHEMICALS ON REDOX CONCEPTAbstractThe problem in this study is that there are still many students who have difficulty learning basic chemical concepts and experience misconceptions. One way to overcome student difficulties in understanding the concept of chemistry is to provide quality learning media. This study aims to produce learning media in the form of quality teaching materials. The teaching materials developed are chemical teaching materials based on Conceptual Change Text (CCT). The research data were obtained from the results of validation of teaching materials from experts and the results of a questionnaire distributed to 30 students. This research was conducted using the R&D method with the research subjects being teaching materials and students. Based on the data generated in this study, it was found that the development of CCT-based teaching materials when viewed from the aspects of content feasibility, presentation feasibility, language assessment, multiple chemical representations assessed by some experts, it can be concluded that the teaching materials developed are good and suitable for use in the field with some improvements with an average validation value of 4. Besides, a limited test was also carried out on students of the teaching materials that were being developed and students responded well to the teaching materials because it could help them understand the average value of 85. AbstrakPermasalahan dalam penelitian ini adalah masih banyaknya mahasiswa yang mengalami kesulitan dalam belajar konsep kimia dasar dan mengalami miskonsepsi. Salah satu cara untuk mengatasi kesulitan mahasiswa dalam memahami konsep kimia adalah menyediakan media pembelajaran yang berkualitas. Penelitian ini bertujuan untuk menghasilkan media pembelajaran berupa bahan ajar yang berkualitas. Bahan ajar dikembangkan adalah bahan ajar kimia berbasis Conceptual Change Text (CCT). Data penelitian diperoleh dari hasil validasi bahan ajar dari para ahli dan hasil angket yang disebarkan kepada 30 orang mahasiswa.  Penelitian ini dilakukan dengan metode R&D dengan subjek penelitian adalah bahan ajar dan mahasiswa. Berdasarkan data yang dihasilkan dalam penelitian ini diperoleh hasil bahwa pengembangan bahan ajar berbasis CCT jika dilihat dari aspek kelayakan isi, kelayakan penyajian, penilaian bahasa, penilaian multiple representasi kimia yang dinilai oleh beberapa ahli dapat disimpulkan bahwa bahan ajar yang dikembangkan sudah baik dan layak digunakan di lapangan dengan beberapa perbaikan dengan rata-rata nilai validasi 4. Selain itu juga dilakukan uji terbatas terhadap mahasiswa terhadap bahan ajar yang sedang dikembangkan dan mahasiswa merespon dengan baik bahan ajar tersebut karena bisa membantu mereka dalam memahami dengan rata-rata nilai 85. konsep.

Analysis of reduction of COD (Chemical Oxygen Demand) levels in tofu waste using activated sludge method

This study aims to reduce COD (Chemical Oxygen Demand) levels in tofu waste using activated sludge. The method used to conduct this experiment is to use the fermentation method by grouping the tofu dregs samples into three groups. Then the tofu dregs sample was added with 1:3 activated sludge and incubated for two days, four days, and six days. The results showed that samples with an incubation period of 2 days had effectiveness in reducing COD levels in tofu waste as much as52.3%; during the incubation period of 4 days can reduce COD levels by 75.5%, and during the incubation period for six days have 79.8% effectiveness in reducing COD levels. A significant increase in the decrease in COD levels on the sixth day indicates that the microbes in activated sludge can multiply optimally to decompose waste and reduce COD levels optimally. In addition, the incubation time on the sixth day of the nutrients required by microbes increased, thereby increasing microbial activity. So it can be concluded that the incubation process of tofu dregs with activated sludge for six days is effective in reducing COD levels and can overcome environmental pollution problems

Challenge in Biochemistry Courses: A Snapshot of Student Learning Difficulties

Biochemistry with a broad and complex scope of material causes students to have difficulty in visualizing or understanding the concepts (metabolic pathways, molecular structures, and terms in biochemistry).This study aims to get an overview of students' learning difficulties in studying biochemistry. The study used a descriptive method. The research subjects were students of Biology Education at one of the universities in West Sumatra. The research instrument consists of a questionnaire of student opinions on learning difficulties and a test of mastery of concepts. It was found that 26.47% of students had difficulties in molecular structure material, 58.82% in metabolic pathway material, and 14.71% in term in biochemistry material. The students have difficulty in learning biochemistry concepts as shown by average lecture achievement score of 0.51 which is in a quite difficult range. The questionnaire results of student opinions on learning biochemistry show that 27% of students like learning using the practicum method

PROFIL KEMAMPUAN BERINKUIRI SISWA SMA PADA TOPIK PENGARUH PERUBAHAN SUHU TERHADAP SISTEM KESETIMBANGAN KIMIA

Penelitian ini bertujuan untuk memetakan kemampuan berinkuiri siswa SMA pada topik pengaruh perubahan suhu terhadap sistem kesetimbangan kimia. Metode yang digunakan adalah metode penelitian deskriptif, dengan subjek siswa kelas XI sebanyak 212 orang yang berasal dari 4 SMA di kota Bandung dan 1 SMA di kabupaten Bandung Barat. Pengumpulan data dilakukan dengan menggunakan instrumen penelitian utama berupa tes dan instrumen pendukung berupa pedoman wawancara dan studi dokumentasi. Hasil penelitiannya menunjukkan bahwa kemampuan berinkuiri siswa SMA secara keseluruhan pada topik pengaruh perubahan suhu terhadap sistem kesetimbangan kimia diantaranya aspek mengajukan pertanyaan 69,34%, aspek merumuskan hipotesis 58,02%, aspek merancang percobaan 32,08%, aspek mengumpulkan data 75,94%, aspek interpretasi data 75,47% dan aspek menyimpulkan 68,40%.

APAKAH MODEL PEMBELAJARAN PROBLEM BASED LEARNING DAN PROJECT BASED LEARNING MAMPU MELATIHKAN KETERAMPILAN ABAD 21?

Seiring dengan perkembangan jaman yang semakin pesat, peran pendidikan menjadi sangat penting dalam mempersiapkan peserta didik agar memiliki keterampilan abad 21. Salah satu upaya untuk menjawab tantangan ini dengan merubah peran guru dari dari penyedia dan peyampai informasi menjadi fasilitator untuk berbagi informasi dan pengetahuan serta melatihkan kemampuan memecahkan masalah kepada peserta didik. Pembelajaran konstruktivisme menjadi salah satu alternatif dalam melatihkan keterampilan abad 21. Model pembelajaran project based learning dan problem based learning menjadi model yang paling poluler pada pendekatan konstruktivisme. Namun, masih banyak para pendidik yang mengalami kebingungan dalam membedakan dan mengoperasikan  kedua model pembelajaran ini. Oleh karena itu, artikel ini mengulas persamaan dan perbedaan antara project based learning dan problem based learning, serta menjawab apakah kedua model pembelajaran tersebut mampu melatihkan keterampilan abad 21

MISKONSEPSI SISWA YANG MENGGUNAKAN TEKS PERUBAHAN KONSEPTUAL MENGENAI HUKUM-HUKUM DASAR KIMIA

Miskonsepsi merupakan pemodelan yang salah dari suatu fenomena, dimana bagi siswa pemodelan tersebut nampak masuk akal dan berpotensi benar. Pembelajaran yang baik adalah dengan cara memunculkan pengetahuan lama untuk dihubungkan dengan pengetahuan baru.Salah satu metode pembelajaran untuk mendukung proses ini yaitu dengan menggunakan teks perubahan konseptual. Penelitian ini merupakan penelitian deskriptif yang bertujuan untuk menganalisis miskonsepsi siswa yang belajar menggunakan teks perubahan konseptual mengenai materi hukum-hukum dasar kimia.Penelitian dilakukan pada 69 siswa kelas X di SMA Negeri di Kabupaten Bandung Barat. Berdasarkan hasil analisis jawaban siswa, terdapat sepuluh miskonsepsi yaitudalam hukum kekekalan massa, jika massa salah satu unsur dilipatgandakan, maka massa unsur lain juga harus dilipatgandakan dengan kelipatan yang sama (M-1); dalam hukum perbandingan tetap, massa senyawa hasil reaksi adalah penjumlahan massa unsur-unsur yang direaksikan (M-2); dalam hukum perbandingan tetap, massa unsur yang dijumlahkan adalah massa atom relatifnya (M-3); dalam hukum perbandingan tetap terdapat kesalahan matematis dalam menghitung massa unsur yang bereaksi sesuai dengan perbandingannya (M-4); dalam hukum perbandingan berganda, membandingkan salah satu unsur tanpa membuat perbandingan unsur yang lain sama (M-5); dalam hukum perbandingan berganda, menyatakan perbandingan unsur X dengan perbandingan unsur yang bukan X (M-6); dalam hukum perbandingan berganda, persentase unsur X adalah kebalikan dari persentase unsur yang bukan X (M-7); dalam hukum perbandingan volume, jumlah koefisien sebelum dan setelah reaksi adalah sama (M-8); dalam hukum perbandingan volume, jumlah volume sebelum dan setelah reaksi adalah sama (M-9); dalam hipotesis Avogadro, perbandingan koefisien menunjukkan perbandingan massa (M-10)

STUDY OF REACTION PATHWAY AND KINETIC OF ESTRAGOLE ISOMERIZATION TO CIS-ANETHOLE AND TRANS-ANETHOLE

Estragole isomerization in basic condition resulted cis- and trans-anethole. Hence, there were two reaction pathway of estragole isomerization i.e. parallel and consecutive. The reaction pathway gave information about reaction mechanism. Estragole isomerization was carried out in various kind and volume of solvent, base ratios, and at various time and temperature. The products were analyzed by GC-MS, and FTIR. The result showed that the estragole isomerization pathway in ethanol and ethylene glycol was parallel. The mechanism of estragole isomerization proceed through carbanion intermediate with Eatotal of 178,6238 J/mol .Keywords: estragole, cis-anethole, trans-anethole, isomerization pathway

The Relation between Gender, Reasons to Participate in STEM-Related Subjects, Programs and The University Supports On First-Year University Student’s Satisfaction: A Structural Equation Model

First-year student's satisfaction has considered an important factor in the quality education offered by the university program. The objective of this study is to investigate the relationship among gender, a reason to participate in STEM-related subjects, program, and the university support on first-year student's satisfaction of STEM learning. The methods used in this study surveyed student's satisfaction using adapted interest and recruitment in the science questionnaire (IRIS Q) instrument. The questionnaire comprised question items covering school science experiences, sources of inspiration for the choice of education, expectations for future job, first-year experiences as a STEM student, and attitudes to gender equity in STEM. A total of 448 students, first-year students from STEM-related programs, have participated voluntarily in this study. The structural equating model assisted by computer program IBM SPSS Amos 20 was employed to analyze the hypothesized model. The results from the model showed that reason and university support have a positive direct effect on first-year students' satisfaction with STEM learning. From this study, it is suggested for the university to improve first-year student's satisfaction by helping STEM students to develop appropriate expectations of the program, facilitating teaching quality to meet STEM students' learning, and assisting students in developing positive attitudes toward their future carriers

Efektivitas Pembelajaran Stereokimia Berbasis Visualisasi 3d Molekul untuk Meningkatkan Kemampuan Spasial

Penelitian ini bertujuan menyelidiki keefektifan program pembelajaran stereokimia berbasis visualisasi 3D molekul menggunakan salah satu chemical drawing software berbasis open source yakni Avogadro, dan animasi kekiralan melalui komputer untuk meningkatkan kemampuan spasial mahasiswa calon guru. Studi menggunakan quasi experimental control group pretest-posttest design. Instrumen penelitian terdiri dari 25 soal pilihan ganda disertai alasan, disusun berdasarkan indikator tiga dimensi utama kemampuan spasial. Penelitian dilaksanakan di satu LPTK di Provinsi Lampung, semester ganjil Th. Akademik 2014/2015. Subjek penelitian terdiri dari kelas kontrol dan kelas eksperimen, masing-masing ada sebanyak 30 mahasiswa. Hasil penelitian menunjukkan bahwa rata-rata skor post test kemampuan spasial kelompok mahasiswa dengan pembelajaran stereokimia berbasis visualisasi 3D molekul secara signifikan lebih tinggi dibandingkan kelompok mahasiswa yang media pembelajarannya menggunakan molymod. Keefektifan program ditunjukkan oleh peningkatan N-gain dalam kategori sedang dan efek size (d) dalam kategori tinggi untuk ketiga dimensi utama kemampuan spasial