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

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

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

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

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

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