Chemistry

We have measured the linear viscoelastic behavior in the melt of two densely grafted poly͑chloroethyl vinyl ether͒-g-polystyrene comb polymers. Both samples have a backbone of approximately 800 ethyl vinyl ether monomers and the fractions of grafted backbone monomers are 98% and 10%, respectively. The viscoelastic behavior shows remarkable features. The comb polymer with the highest grafting density shows a power law behavior over five orders of magnitude in frequency. The power law can be understood through a ''Rouse-like'' motion of the entire chains with an apparent friction coefficient coming from the fast Rouse dynamics of the short grafts. Alternatively, the same behavior can be described as the signature of a ''fluctuating'' physical gel. The less densely grafted comb polymer has a more complex behavior.

JURUSAN KIMIA FMIPA UNIMED KIMIA FISIK 1(Dr. Zainuddin M, M.Si) TUGAS LATIHAN TUGASTERSTRUKTUR (DIKUMPULKAN SECEPATNYA) 1. Sebuah wadah dengan katup pemisah berisi gas Ne di satu sisi dan gas He di sisi lain dengan keadaan seperti pada gambar 1. Jika dianggap kedua gas adalah gas ideal, setelah katup pemisah dibuka hitunglah : P total , V total , P Ne , P He.

Menjadi manusia yang Gatek (gagap teknologi-informasi) di tengah zaman yang begitu modern saat ini rasanya hampir bisa dipastikan bahwa manusia tersebut akan menjadi kelompok yang termarjinalkan dan akan menjadi kelompok yang aneh karena seluruh aspek kehidupan manusia telah dipengaruhi oleh maju dan pesatnya teknologi informasi. Mereka yang tidak mengikuti perkembangan akan terseret arus kemajuan teknologi. Hanya mereka yang dapat menguasai dan dapat memanfaatkan teknologi informasi itulah yang akan dapat memasuki persaingan baik dalam tataran regional, nasional maupun internasional. Perkuliahan Komputasi Kimia bagi mahasiswa di jurusan kimia dimaksudkan untuk memberikan bekal awal (bontot) agar mahasiswa dapat mengakses teknologi Informasi dan memanfaatkannya tidak hanya selama menempuh pendidikan di Unimed tetapi juga akan bermanfaat setelah menyelesaikan pendidikan. Bagi calon tenaga kependidikan, kepiawaian dalam memanfaatkan komputer dalam rangka pendiversifikasian sumber belajar sangat dibutuhkan terlebih dengan penerapan Kurikulum Berbasis Kompetensi atau terakhir lebih spesifik menjadi Kurikulum Tingkat Satuan Pendidikan (KTSP) yang menuntut guru untuk mampu membuat inovasi dalam media pendidikan. Komputer adalah perangkat yang mumpuni untuk tujuan itu. Juga bagi mahasiswa program studi kimia (lebih gaul disebut nondik) penguasaan teknologi komputer adalah hal yang mutlak dan tidak perlu ditawar lagi. Buku diktat untuk mendukung proses perkuliahan bagi mereka yang berbelanja matakuliah Komputasi Kimia ini, mengenalkan kepada mahasiswa software-software yang termasuk dalam keluarga MS Office, yaitu MS Word, MS PowerPoint, dan MS Excel. Disamping itu juga diperkenalkan software Kimia yang sederhana yaitu ISIS/Draw versi 2.3 untuk mendukung keleluasaan mahasiswa dalam penulisan struktur kimia, khususnya kimia organik yang belum tersedia perangkatnya di dalam MS Office. Buku ini sebenarnya adalah sumber minimal, mahasiswa dapat memperkayanya dengan melirik buku-buku praktis lainnya. Untuk kemahiran, dengan pertimbangan limitasi waktu praktikum, mahasiswa diharapkan dapat berlatih secara mandiri di luar jam kuliah. Buku sederhana ini tidak tertutup kemungkinan untuk digunakan oleh pemakai lainnya, khususnya untuk tujuan penulisan naskah yang sederhana, baik untuk presentasi, pengolahan data dll.

This study aimed to determine the differences in chemistry learning results by Numbered Heads Together (NHT) type of cooperative model. This model used student worksheet media compared to question card media on salt hydrolysis. The results shown that there were differences in the learning outcomes in SMA N 1 Perbaungan 2016/2017. The analysis data shown for the gain value in the first experiment class reached 73.19% and the second experiment class 67.57%. The data processing obtained the average value of pre-test and post-test in the first experiment class (33.78) and (82.42) respectively. In the second experiment class cheieved the average value of pretest (33.48) and posttest (78.48). The difference in increasing learning outcomes achieved 5.62%.

The use of android-based learning media is one of the 21st century learning style applications. By using media that have been developed, this research was also conducted to find out the improvement of student learning outcomes. The population in this study were 2 class XI IPA of SMA Negeri 1 Sidamanik, where the experimental class 1 was given an integrated e-worksheet of problem based learning and the experimental class 2 was given a power point with a direct interaction model. This research uses methods and media development (R&D). The results of the feasibility analysis of the e-worksheet on the aspect of content eligibility are 4.75; language eligibility is 4,80; the feasibility of serving is 4.82 and the feasibility of serving is 4.14. By using e-worksheets that integrate problem based learning in the reaction rate material obtained an increase in learning outcomes of 82.4% with the highest value of 95 and the lowest value of 75 both of which have passed the KKM of 70. Hypothesi...

This study aimed to determine the differences in chemistry learning results by Numbered Heads Together (NHT) type of cooperative model. This model used student worksheet media compared to question card media on salt hydrolysis. The results shown that there were differences in the learning outcomes in SMA N 1 Perbaungan 2016/2017. The analysis data shown for the gain value in the first experiment class reached 73.19% and the second experiment class 67.57%. The data processing obtained the average value of pre-test and post-test in the first experiment class (33.78) and (82.42) respectively. In the second experiment class cheieved the average value of pretest (33.48) and posttest (78.48). The difference in increasing learning outcomes achieved 5.62%.

The COVID-19 pandemic forces learning activities to change from classroom learning to online-based learning Based on the results of the interview, it was found that the teachers at Nurul Fadhilah school did not yet have the readiness to manage online teaching and learning activities, especially in science subjects The influencing factors are (1) understanding of basic science concepts (physics, chemistry, biology), (2) understanding of systematic online learning management and (3) mastery of Learning Management System (LMS) technology Therefore, the aim of this activity is to implement LMS technology in the management of online science learning using a basic conceptual approach to chemistry education LMS is a technology application developed specifically for managing classrooms, distributing learning materials and enabling collaboration between students and teachers online The LMS used in this activity is Google Classroom Based on the data, it is known that 65% of the teachers at Nu...

The complex of Cu(II) 1,2,4 H-triazole is one complex compound having a polymeric structure. The objective of this study determines the difference in energy formation and structure data of Cu(II) 1,2,4 H-triazole complex. The computational study used the Hartree-Fock method and the basis set 3-21G and 6-31G(d). The complex was studied of [Cu 2 (Htrz) 4 (trz) 2 ] 2+ and [Cu 2 (Htrz) 6 ] 4+. The result of a computational study with function/ basis set UHF/ 6-31G(d) shows the distance between Cu(II) ions for complexes with deprotonated ligands of 3,433Ǻ, while complexes with undeprotonated ligands are 3,551Ǻ. Bond length of Cu-N in the complex with deprotonated ligands are 1.953Ǻ-2.167Ǻ, whereas for the complex with undeprotonated ligands are 2,063Ǻ-2,123Ǻ. The difference of energy from a computational study using the function/ basis set UHF/ 6-31G(d) for the [Cu 2 (Htrz) 4 (trz) 2 ] 2+ complex is-3693.43 KJ/ Mol and the [Cu 2 (Htrz) 6 ] 4+ complex is-1666.01 KJ/ Mol.

Jatropha leaves from Durian, Labu Beach, North Sumatera was prepared as a biosorbent for the selectivity absorption of Pb 2+ and Cd 2+ in their mixture system. Jatropha curcas leaves was prepared by heating at 105 o C for 4h, then characterized by XRD and FTIR. FTIR spectra indicate the content of organic groups as-OH,-CN and-CO groups in their function to reduce of Pb and Cd ions in liquid contaminant. Pb 2+ and Cd 2+ were adsorbed in the single system obtained as optimum amount of Pb 2+ at 100 mgL-1 and 60 min contact time is 4.72 mgg-1 which higher than Cd 2+ as 4.42 mgg-1 at 100 mgL-1 ion solution for 90 min. Interestingly, in the mixture solution of Pb and Cd ions, Cd 2+ was adsorbed as 2.64 mgg-1 which higher than Pb 2+ adsorption amount as 2.11 mgg-1 at 100 ppm solution and adsorption time for 90 min. It indicates the mixture content of Pb and Cd ions in liquid solution shows a preferential adsorption properties compared with their single system adsorption.

This study aimed to develop an Android-based learning media integrated with a scientific approach to the colligative solution's nature. This study uses the Research and Development (R & D) method with the ADDIE model development stages. The population of the study was all students of class XII SMA using the 2013 curriculum. The sample was class XII SMA Swasta Al - Azhar Medan. The validation of learning media based on Android integrated scientific approach by material experts and media experts obtained a feasibility score of 4.4 and 4.8, respectively. In contrast, the feasibility score by two chemistry teachers received an average value of 4.7. The validation of Android-based learning media integrated with the scientific approach shows that the average score is 4.6, which means that the learning media used has very feasible criteria. Android-based learning media products integrated with the scientific approach were tested on 26 students of class XII at Al-Azhar Medan Private Hig...