Jurnal Pendidikan Kimia
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The Effect of Catalyst in the Process of Nano-Silica Particle Formation as a Hydrophobic Material
Get PDFNano Silica is known as a hydrophobic material used to coat the material that further modifies the surface properties of the material. In this study the process of making nano silica material is using sol-gel method. The sol gel process is defined as the process of forming an inorganic compound through chemical reaction in solution at a low temperature wherein the process a phase changes from the colloidal suspension (sol) to a continuous liquid phase (gel). The types of catalyst were studied. The result was then applied to cotton, polyamide and silk fabrics. Acid catalyst showed the greatest moisture reduction based on Moisture Content and Moisture Regain evaluation in cotton and polyamide fabrics, whereas base catalysts showed a significantly less moisture reduction on the three fabrics. The use of these types of catalyst will also affect the value of the tensile strength of each fiber. Tensile test results showed that the use of acid catalysts decreased the maximum tensile strength in cotton fabrics by 88.57%, compared to polyamide and silk fabrics and the use of base catalyst showed less significant decreased on tensile strength for all fabrics
Practicality Analysis of Developing the Student Worksheet Oriented Blended Learning in Acid Base Material
Get PDFThis study aims to produce a Student Worksheet (LKPD) in an integrated manner with blended learning oriented, the learning was carried out based on 1) the online and offline activities of students; and 2) student responses. The design of this study was using the stages of defining, designing, and developing, followed by testing. Data collection had been conducted by using instruments for measuring student activity and responses. The results of this study indicate that 1) the online and offline activities of students were 97.03 and 98.33%, respectively and 2) the results of the questionnaire responses of students were 93.33%. Based on the results of the response and online and offline activities it can be indicated that the development of LKPD is very practical to be use in acid-base subject learning.
Improving Ethanol Permeation Efficiency Using Modified Poly(Vinyl Alcohol) Membrane
Get PDFThis research is about using blended membrane poly(vinyl alcohol)-pectin that are crosslinked by glutareldehide for ethanol permeation. Poly(vinyl alcohol) or PVA is used as the base membrane, pectin as biopolymers and gluteraldehida (GA) as a crosslinker agent. The objective of this study is improving the efficiency of ethanol permeation using blended PVA membrane with pectin and glutaraldehyde to determine the optimum composition of blended membrane PVA-pectin-GA. Membrane with optimum composition is selected based on the highest flux value. Membrane optimization was obtained by studying the effect of the PVA concentration, the addition of GA and pectin. Moreover, optimization was studied based on membrane permeation rate (flux) of ethanol that passes through the membrane. Membranes with high flux value were selected as the optimum membrane. The results conclude: (1) Addition of gluteraldehide decreased flux values but increased membrane stability. The highest flux value generated from the blended membrane that has cross-linker number (n) 120; (2) Addition of pectin increased flux value but decreased membrane stability. The highest flux value was obtained from blended membrane of PVA-pectin-GA with the optimum composition on mole ratio of PVA: pectin = (1: 2)
Antioxidant Activity of Methanol Extract of the Purun Tikus (Eleocharis dulcis) Leaves
Get PDFPurun tikus (Eleocharis dulcis) is a kind of swamp plant, can be found in open water areas, both in swamps and rice fields. Purun tikus is an indicator vegetation of acidic sulfate soil. Chemically, plants that able to adapt to special or extreme conditions, usually produce a compound that are unique and have unique bioactivity as well. This paper reports a phytochemical screening of Purun tikus methanol extract and its antioxidant activity. The results showed that the methanol extract of Purun tikus leaves contained phenolic compounds, flavonoids, tannins and terpenoids. By using DPPH method as an antioxidant test, the methanol extract of purun tikus leaves showed a strong activity, with IC50 value was 58.58 ppm while vitamin C had an IC50 value of 4.50 ppm
Development of Organic Chemistry I Learning Module Integrated Experiment Based on Conceptual Change Model ED3U (Explore, Diagnose, Design, Discuss, Use)
Get PDFOrganic Chemistry lecture requires the student to be able to think critically in getting knowledge and prove the facts through experiment. The problem of this lesson is the students have different ability to receive the concepts. To overcome this matter a teaching material, like a module which can facilitate the students who cannot follow lecture well is needed. Therefore, a module which is based on the conceptual change model ED3U (Explore, Diagnose, Design, Discuss, Use) was developed with the steps that activate critical thinking and skilled which appropriate for the learning outcome in alcohol lesson. The module was validated, tested for its practicality and affectivity to ensure the quality and functionality of the module to help students gained conceptual change. The instrument used for validity and practicality test was questionnaire, while test was used for evaluating its effectiveness. The Data was analysed using Cohen Momen Kappa Formula. The result showed that the module developed was valid, practical and effective and fit the category very high with the positive result for conceptual change.
Validation of the TSH IRMA Kit for Determination of the TSH Levels in Human Blood Serum
Get PDFTSH IRMA kit is a kit used for the determination of TSH (Thyroid Stimulating Hormone) levels in human blood serum. Thyroid hormone is a hormone that our bodies need for growth of the brain, bone and other tissues and regulate the metabolism in the body. TSH normal range for adult is in the range of 0.4-4.5 mIU/L, whereas for baby is about 3.0-18.0 mIU/L. Thyroid would affect the quality of optimal growth of children if disturbed. Therefore, TSH assay in the blood needs to be determined to know whether the function of the thyroid gland works normally or not. Detection of TSH in blood can be performed by Immunoradiometricassay (IRMA) method. IRMA method is one of the immunoassay techniques based on immunological reactions (antigen-antibody binding) using radionuclide 125I as a tracer, that sample in small quantity can be detected. IRMA method was developed locally by replacing TSH IRMA kit which is costly since imported from commercial companies. Center for Radioisotope and Radiopharmaceutical Technology (PTRR) BATAN has successfully developed the TSH IRMA kit that can be used to determine the levels of TSH in human blood. TSH IRMA kit must be validated to know the limit of detection, sensitivity, accuracy, precision and the assay parameters, such as Non-Specific Binding (NSB) and Maximum Binding (MB). Validation of TSH IRMA kit had been carried out resulting in the limit of detection of 0.115 ng/mL, accuracy with a recovery of 93.6-108.0 %, intra-assay precision (% CV) QC L = 1.9848, QC M = 3.6360 % and QC H = 2.2085 % while the inter-assay precision (% CV) QC L = 11.0055, QC M = 5.6768 % and QC H = 5.4181 %. It was concluded that this TSH IRMA kit showed good performance based on the % NSB and % B/T of 0.68 and 34.64 %, respectively
Validation of Atomic Absorption Spectrometry Method for Contamination Determination of Lead (Pb) and Cadmium (Cd) in Methanol Extract and Product of Curcuma xanthorrhiza Roxb.
Get PDFThe validity of atomic absorption spectrometry method for lead (Pb) and cadmium (Cd) determination in methanol extract and product of Curcuma xanthorrhiza was unknown. The aim of this work is to determine the validity of atomic absorption spectrometry method for Pb and Cd determination in methanol extract and product of Curcuma xanthorrhiza. Digestion process was done by wet digestion method and its results were read by atomic absorption spectrometry at a wavelength 217.0 nm for Pb and 228.8 nm for Cd. Validation results found % recovery of Pb and Cd respectively were 87.16% ± 0.38 (RSD 0.42) and 89.10% ± 0.06 (RSD 0.07) in methanol extract of Curcuma xanthorrhiza, 92.62% ± 0.24 (RSD 0.26) and 100.16% ± 0.07 (RSD 0.07) in Curcuma xanthorrhiza product. Precision test found the RSD value for Pb in the methanol extract and product of Curcuma xanthorrhiza were 0.02 and 0.14 respectively, but the RSD value for Cd were not detected. The linearity test results of Pb and Cd standar solution were 0.9998 and 0.9979. The LOD for Pb and Cd were 0.4 ppm and 0.1 ppm, and the LOQ were 1.3 ppm and 0.5 ppm respectively. Based on the % recovery results, the method of Pb and Cd determination by atomic absorption spectrometry is valid for methanol extract and product of Curcuma xanthorrhiza. The levels of Pb in extract and product of Curcuma xanthorrhiza were 2.10 ± 0.001 mg/kg and 4.34 ± 0.001 mg/kg respectively, but the levels of Cd in both samples did not detected.
Analysis of High School Students’ Argumentation Ability in the topic of Buffer Solution
No full textArgumentation is scientific discourse in science learning that is used as a link between knowledge from an environment and concepts in science learning. Through argumentation skills can be controlled student understanding in connecting facts with concepts in learning. This study aims to analyze students' argumentation ability on buffer solution subject. Students' argumentation ability is divided into 4 levels; level 1 (claims), level 2 (claims with data), level 3 (claims with data and one rebuttal), and level 4 (claims with more than one rebuttal). Data analysis was done by a qualitative descriptive method using a case study method. The case study method was chosen so that a study of 92 students who were research participants could be carried out in depth and comprehensive. The results obtained that the students' argumentation ability was at level 1 and level 2 argumentation. This shows that students' argumentation skills are still at low and medium levels. The results of this study can be used as a basis for improving the quality of teaching and further research
Phytochemical Test and Antibacterial Test of Rhizopora apiculata Mangrove-Root against Escherichia coli and Staphylococcus aureus Bacteria
Get PDFIndonesia has many kinds of mangrove but they have not been widely utilized as health food and medicinal products because of the limited information and research on the content of bioactive compounds in the mangroves. One of the mangrove species that are found in the Bontang mangrove forest, East Kalimantan is R. apiculata. It is used as fuel, building materials, shipbuilding, and as traditional medicine. This study aims to determine the class of secondary metabolites compounds and the antibacterial activity of methanol extract of R. apiculata mangrove roots. The extraction was performed by maceration method using methanol solvent. Secondary metabolites compounds class in the mangrove sample was determined qualitatively by using several phytochemical reagents. Antibacterial test against E. coli and S. aureus were performed using diffusion method with various concentration of the roots-mangrove methanol extract of 500, 250, and 125 ug/well. Incubation was performed in various time of 12, 24, 48 and 72 hours. Phytochemical test results showed that the roots-mangrove methanol extract of R. apiculata contained secondary metabolites classes of alkaloids, flavonoids and triterpenoids. The extract does not inhibit the growth of E. coli, but it could inhibit the growth of S. aureus at 500 ug / well with incubation time of 12, 24, 48 and 72 hours and have inhibition zones of 7.95 mm, 8.3 mm, 8.0 mm, and 7.0 mm, respectively. At a concentration of 250 ug/ well with an incubation time of 48 hours has a 7.5 mm of inhibition zone. Those inhibitions are relatively weak category
Development of Interactive Chemistry Learning Devices using Domino Chemical Media in terms of Student Activity and Learning Outcomes of Class X High School in Samarinda
Get PDFThis research focuses on research and development of learning devices using Chemical Domino media. The product of this research is Interactive Chemical Domino learning media, which focused on compound nomenclature material for class X which is expected feasible to be used as learning media. The subjects in this study are divided into 2 stages, the first is the small group test in which only 12 students from SMA Negeri 1 Samarinda participate. The second is field test (large group) which 96 students from 3 high schools participate, namely SMA Negeri 1 Samarinda, 36 students from Madrasah Aliyah Negeri 2 Samarinda, and 36 students from SMA Negeri 5 Samarinda. The results showed that the validation of media experts scored 85.77%, material expert validation scored 88.63%. In learning media validation, it showed that validation of RPP scored 92.08%, LKS validation scored 92.67%. For student response results scored 81.25%. From those scores it can be concluded that development of learning device using Media Chemical Domino is "very good”. Meanwhile for the observation results of student activity increased up to 33.71% and for student learning results from posttest and daily test reach KKM with percentage of student learning result 77,34%.