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INDONESIA
Jurnal Pendidikan Kimia (JPKim)
Published by Universitas Negeri Medan
ISSN : 20853653     EISSN : 25493116     DOI : 10.24114
Core Subject : Science, Education, Social,
Biochemistry, Genetics & Molecular Biology Chemistry Education Environmental Science
Jurnal Pendidikan Kimia (JPKim) yang dikelola Program Pascasarjana Universitas Negeri Medan terbit 3 kali setahun, yakni bulan April, Agustus dan Desember. JPKim menerbitkan artikel ilmiah hasil-hasil penelitian pendidikan kimia dan kimia fundamental. JPKim juga menerbitkan artikel Review terkait Pendidikan Kimia dan Kimia.
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Articles 12 Documents
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Search results for , issue "Vol 13, No 3 (2021): December" : 12 Documents clear
Methanol extract from kesambi (Schleichera oleosa (L.) oken) stem bark as a natural antioxidant to increase crude palm oil (CPO) quality Weny J A Musa; Nurhayati Bialangi; Diky Kurniawan; M Amrin Sunardi; Ninik Triayu susparini; Sriwijayanti Sriwijayanti; Boima Situmeang
Jurnal Pendidikan Kimia (JPKim) Vol 13, No 3 (2021): December
Publisher : Pascasarjana Universitas Negeri Medan

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (340.16 KB) | DOI: 10.24114/jpkim.v13i3.29018

Abstract

The content of active compounds in methanol extract of kesambi stem bark (Scheleicera oleosa) is known to have good antioxidant activity. Methanol extract of kesambi stem bark contain flavonoid and fenolic compounds. The purpose of this study was to evaluate the methanol extract of kesambi in inhibiting the oxidation of crude palm oil (CPO). In this study, the extraction of kesambi stem bark was carried out with methanol solvent. Antioxidant activity test of methanol extract of kesambi using the DPPH method. The parameters observed were free fatty acids (FFA) values, acids value, and DOBI (Deterioration of Bleachability Index). The used concentration of natural antioxidant were 200; 400; 600; 800 and 1000 ppm. Based on the results of this study, the natural antioxidant of methanol extract of Kesambi stem bark (Schleichera oleosa) can reduce levels of free fatty acid numbers, acid value, and DOBI value. Actioxidant activity methanol extract of kesambi stem bark shown IC50 42.092 ppm. The lowest FFA levels and acid numbers were obtained from samples with addition of 1000 ppm natural antioxidants with free fatty acid (4.1%), acid value (7.7 mg KOH/g) while the DOBI value increased to 1.331. Furthermore, FFA value meets the CPO quality standard, according to SNI-01-2901-2006. Keywords: Crude palm oil, antioxidant, free fatty acid (FFA), acid value
The effectiveness of the four-step jigsaw and jigsaw learning model in improving students' argumentation skills about salt hydrolysis concept Windy Kartika; Asrial Asrial; Muhammad Haris Effendi-Hasibuan
Jurnal Pendidikan Kimia (JPKim) Vol 13, No 3 (2021): December
Publisher : Pascasarjana Universitas Negeri Medan

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (329.145 KB) | DOI: 10.24114/jpkim.v13i3.29929

Abstract

One of the learning models that can train students in developing argumentation skills is the jigsaw learning and its modified forms. This study aimed to see the effectiveness of the four-step jigsaw learning and the Jigsaw learning in improving students' argumentation skills about the concept of salt hydrolysis. This study was conducted with 2 classes of 11 grade students of SMAN 7 Kerinci Jambi. Some 53 students in total were purposively recruited and participated in this experiment. Concurrent embedded mixed method with two-group pretest-posttest control group design was used in this study. The results of independent t-test showed that 4SJ was more effective than the Jigsaw class (t= 2.668; p-value = 0.01 < 0.05). It was supported by the n-Gain of 4SJ which was 0.71 and the n-Gain of jigsaw was 0.67. Two factors that influenced the differences in students' argumentation skills were observed; these included the difference in learning duration and the intensiveness in conducting the argumentation debate. Keywords: argumentation ability, four-step jigsaw, jigsaw, salt hydrolysis

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