JKPK (Jurnal Kimia dan Pendidikan Kimia)
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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.  Â
Development of Applicative-Integrative Student Worksheet Based on Scientific Approach on Reaction Rate Subject
Get PDFThis research aimed to design applicative-integrative student worksheet based on scientific approach, which was applied to the learning process by using guided inquiry learning model. The worksheet was properly assessed from three aspects. There were validity, effectivity and practicality. The approach used in this research was ADDIE approach (Analysis, Design, Development, Implementation and Evaluation) with Embedded Mixed Methods. The stages of this research were extraction of potentials and problems, designing student worksheet, validation by experts including media, subjects, and practitioners, then testing the student worksheet. The results showed that the student worksheet was appropriate based on the analysis of the data obtained. This student worksheet was feasible to be implemented in the learning process of chemistry class, particularly reaction rate subject. The result of this research showed that validity, effectivity and practicality obtained 93.9, 83.1, and 94.3%, respectively.Â
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
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 goodâ€. 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%.Â
Isolation of Ferulic Acid from Leaves of Mindi (Melia azedarach L.) and Its Antioxidant Activity Test
Get PDFMindi (Melia azedarach L.) is one of a plant from Meliaceae family and has been known for its bioactive compound, such as ferulic acid. On this study, the isolation of ferulic acid and antioxidant activity test has been conducted. The aim of this study was to isolate the ferulic acid on ethanol extract of Melia azedarach L. leaves, determine the ferulic acid content and antioxidant activity test qualitatively. The method used in this research was isolation with hydrolysis (acid and base) and without hydrolysis, determining the phenolic acid content using TLC scanner instrument and antioxidant activity test qualitatively using DPPH radical reduction method. According to the identification using TLC and TLC scanner, the base hydrolysis fraction (HB), acid hydrolysis (HA), and without hydrolysis (HA) of ethanol extract from Melia azedarach L. was suspected contain the ferulic acid compound. The analysis result using TLC scanner was known to have ferulic acid content on HB, HA, and TH fraction of 15.57%,12.17%, and 9.56%, respectively. This study showed that hydrolysis affected the phenolic acid content where the HB fraction produced higher ferulic acid than HA and TH fraction. The antioxidant activity test that has been conducted qualitatively showed that ferulic acid isolates contained on each fraction actively reduce the DPPH radical
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)
Estimation of Air Pollutant Emissions in Eastern Indonesia from Non-Oil and Gas Sources (Case Study in Sulawesi and Papua)
Get PDFEstimation of air pollutant emissions from non-oil and gas sources in eastern Indonesia, namely Sulawesi and Papua provinces during the period 2014 – 2016 was conducted. This paper intended to estimate the emission of three air pollutants namely NOx, SO2 and CO2. The aim was to find out the amount of pollutant and greenhouse gas (GHG) emissions in the Sulawesi and Papua regions. The method used was the emission estimation method based on statistical data of Gross Regional Domestic Income (GRDP) in the Papua and Sulawesi regions. The results from estimation of pollutant emissions was then carried out for pollutant emissions mapping. The pollutant emission estimation showed the emission of air pollutants in Sulawesi region was higher than Papua. The mapping of emissions in Sulawesi were consisted of four provinces, namely north, central, south and southeast Sulawesi. The Papua region were consisted of Papua and west Papua provinces. The highest emission in Sulawesi region was south Sulawesi. The CO2 emission in Sulawesi was increase about 23% with the detail value; 84.4 tons in 2014; 94.3 tons in 2015; and 103.7 tons in 2016. The emission of NOx during 2014 until 2016 are 0.53, 0.58 and 0.64 tons, there was an increasing in the emission of NOx around 21%. In addition, SO2 emission of south Sulawesi are 0.42 tons in 2014, 0.47 tons in 2015 and 0.51 tons in 2016, increased about 21 % during the year 2014 - 2016. In the Papua region, the emission in Papua was higher than Papua Barat province. CO2 emissions in Papua during 2014 -2016 were 112, 124.8 and 144.99 tons, it means the CO2 was increased 29%. The emission of NOx during 2014-2016 were 0.70, 0.77 and 0.89 tons, increased around 27%. In addition, SO2 emission was increase 26% with the detail value; 0.56 tons in 2014; 0.61 tons in 2015 and 0.71 tons in 2016.Â
The Effect of Chemistry Learning with PjBL and PBL Model Based on Tetrahedral Chemistry Representation in term of Student’s Creativity
Get PDFThis research aims to know: (1) the effect of PjBL and PBL models based on tetrahedral chemistry representation toward student’s achievement; (2) the effect of creativity toward student’s achievement; and (3) the interaction between PjBL and PBL models based on tetrahedral chemistry representation with creativity toward student’s achievement on the colloid subject in SMA Negeri 1 Sragen. This research used quasi experiment method with 2×2 factorial design. Samples of research were determined with cluster random sampling technique and used 2 classes in SMA Negeri 1 Sragen. Data has been collected by test, questionnaire, observation, and literature documents which owned by teacher. Hypothesis testing of this research for cognitive and skill aspects of learning achievement used parametric test of Anova two ways, and for attitude aspect of learning achievement used non-parametric test of Kruskal-Wallis. The results of this research showed that: (1) there was no effect of chemistry learning using of PjBL and PBL models based on tetrahedral chemistry representation toward knowledge, attitude, and skill aspects of student’s achievement; (2) there was effect of high and low creativity toward knowledge and skill aspects of student’s achievement but there was no effect toward attitude aspect of student’s achievement; and (3) there was no interaction between using PjBL and PBL models based on tetrahedral chemistry representation with creativity toward knowledge, attitude, and skill aspects of student’s achievement.Â
Acid Base Indicator from Shoot-Leaves Ethanol Extract of Pucuk Merah (Syzygium oleana)
Get PDFExperiment on natural acid-base indicators is usually done by extracting the natural sources with certain solvent, testing the extract with acid, base and neutral solutions, observing the color changes, making conclusion and discharging the remaining extract at the end of the experiment. Production of long-lasting natural acid-base indicator is needed to reduce the discharged of chemicals excessively. This research was carried out to produce natural acid-base indicator from extract of shoot leaves of Syzygium oleana (SLS). The extraction was done by maceration technique using ethanol 95% for 13 h. The extract of SLS (SLS indicator solution) is then used to produce SLS indicator paper by soaking the filter paper in SLS indicator solution and followed by drying under shade. Both of the solution and paper indicators were tested for their color changes in pH solutions range of 1-13. Durability and performance of the indicator was investigated for 6 d. Absorbance of the indicator solution was measured under wavelength of 200-700 nm by using UV-Vis spectrophotometer. The results showed that, both of the indicators can be used as acid-base indicator; even it can be used to determine the pH range of solution. The color changes of SLS indicator in solution pH of 1-13 were pink-fade green-moss green-brown. Both of the indicators showed a good performance in their color change for 6 d of storage. Thus, the ethanol extract of SLS can be used as raw material to produce acid-base indicator
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.Â