Jurnal Akademika Kimia
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Analysis of Primary Metabolic Compounds in Durian Seed Flour (Durio zibethinus Murr) Typical of Central Sulawesi (Parigi Moutong)
Get PDFThis study aims to determine the carbohydrate, protein, and fat content of durian (Durio zibethinus Murr) seeds from Parigi Moutong. This study consisted of two samples, namely, sample A (crushed durian seeds) and sample B (mashed and sifted durian seeds)—Soxhlet method. The results obtained in sample A for carbohydrate content of 52.8 %, protein 3.50 % and fat 2.06 % while in sample B for carbohydrate content of 43.2 %, protein 2.27 % and fat 2.25 %. Based on the results obtained, durian seed flour can be used as processed food and can be of economic value if it is further processed and traded
Improving Student Learning Outcomes by Applying the Discovery Learning Model to the Acid-Base Titration Material of Senior High School
Get PDFThe acid-base titration topic has links between concepts, equations of reactions, and calculations. Therefore, the lack of mastery related to this topic will affect the low learning outcomes. This study aimed to improve student learning outcomes on the acid-base titration topic by applying the discovery learning model. The sample of this study was students of class XI MIPA SMA Negeri 5 Palu, consisting of class XI MIPA 5 as experimental class 1 (n = 35) and class XI MIPA 6 as experimental class 2 (n = 33). The effectiveness of applying the discovery learning model can be seen from the average N-gain value in the experimental class. For experimental class 1, the average N-gain value was 0.67, which is included in the medium category. While the experimental class 2 was 0.63, which is included in the medium category. Based on the results of data analysis, the average value of student learning outcomes for experimental class 1 was 76.42 and experimental class 2 was 75.3. This value was greater than the average student learning outcomes before the treatment, which were 65. So it can be concluded that applying the discovery learning model can improve students’ learning outcomes in class XI MIPA on acid-base titration topics in SMA Negeri 5 Palu
Effectiveness of Purification Used Cooking Oil Using Adsorbents: Activated Charcoal Seeds Salak (Salacca zalacca)
Get PDFSalak seeds have a reasonably high cellulose content. This suggests that salak seeds can be used as a raw material for producing activated charcoal to refine used cooking oil. This study aims to determine the effectiveness of refining used cooking oil using active charcoal adsorbents derived from Salacca zalacca seeds. The methods used to determine free fatty acid levels and peroxide values are the acid-base and iodometric titration methods. This study will observe several variables that affect the adsorption process, namely the mass of activated charcoal and the contact time of used cooking oil. The results showed a decrease in free fatty acids and peroxide number, and the colour of the oil became brighter with increasing adsorbent and contact time. The best results were obtained at a mass of 15 grams and an adsorption time of 120 minutes. Based on the quality requirements for cooking oil as specified in SNI 3741-1995
Synthesis of Fluorescent Carbon Dots from Soybean Residuals Using Hydrothermal Method
No full textSoybean residuals are biowaste composed of carbon chains and amine groups bounded in peptide linkages. The component was identified through FTIR analysis which showed the vibration of the diamide bond (N=C=N) at wave number 2132cm-1. Owing to the existence of these components, soybean has the potential to be used as a precursor to synthesize carbon nano-material, such as Carbon Dots (C - Dots). In this study, the synthesis of C - Dots material from soybean residuals was carried out using the facile hydrothermal method at a temperature of 200 oC for 6 hours. Afterward, the as-synthesized C - Dots were analyzed for their optical property, structure, and morphology. Based on the analysis of the UV - Vis and photoluminescent spectra, C - Dots exhibited absorbance peaks of 292 nm and 301 nm in the UV light region, and fluorescence emission peaks of 468 nm, with blue luminescence characteristics. The observation was supported by the morphological analysis using the HR - TEM, C - Dots exist in a spherical shape with an average particle size of 3.467 nm and a lattice distance of 0.363 nm. Besides, the C - Dots exhibited a good quantum yield of 28.15 %. From the results of the analysis, it is known that the synthesis of C - Dots material has been successfully carried out with particle size < 10 nm
Antioxidant Activity Test of Ethanolic Extract of Tempuyung Leaves (Sonchus Arvensis L.) Based on Linoleic - Thiocyanic Method
No full textFree radicals chemically have free electrons, free radicals tend to take electrons from other molecules, which then give rise to abnormal compounds. Antioxidants are substances that can delay or prevent free radical oxidation reactions in lipid oxidation. Tempuyung leaves contain flavonoids which can act as antioxidants. This research aims to determine the antioxidant activity of the ethanol extract of tempuyung leaves using the linoleic-thiocyanate method and to determine the total phenolic and total flavonoid content using the Folin-Chiocalteu reagent method. The results showed that the ethanol extract of tempuyung leaf extract had antioxidant activity. Percentage of antioxidant activity of 10 % extract = 82.91 %, 5 % extract = 70.07 %, 1 % extract = 57.70 %, Vitamin E 1 % = 70.2 1%. Total phenolic content of 10% extract = 0.48 %, 5 % extract = 0.25 % and 1 % extract = 0.04 %. The total flavonoid content of the extract is 10 % = 0.14 %, 5 % extract = 0.07 %, and 1 % extract = 0.02 %. Pearson correlation test showed that phenolic and flavonoid compounds greatly influenced the antioxidant activity of the ethanol extract of tempuyung leaves
Synthesis of Silver Nanoparticles using Gandaria Seeds Bioreductor
No full textThe silver nanoparticles (NPP) are synthesized with the chemical reduction method by using a water extract bioreductor of gandaria seed (Bouea macrophylla G.) which acts as a reducing precursor, in this case, AgNO3 Ag+ is reduced to AgO. The concentration of AgNO3 is made between 0.5 mm and 1 mm. The characteristic of NPP is unstable, so a modification is needed with and without the addition of PVA 1 %. The process of NPP shaping is monitored by observing the uptaken of UV - Vis when the color changes occur. The high NPP concentration of AgNO3 has higher absorbance and is wider if compared to the lower AgNO3 concentration. The result of this research based on the absorbance value and the wavelength showed the NPP synthesized without the addition of PVA 1 % (b/v) is wider. The addition of PVA 1 % (b/v) provides better stability and maintains the absorbance of spectrum changes from day to day. The maximum uptaken of UV-Vis from NPP AgNO3 0.5 mm by using green synthesis and 1 mm without adding PVA are 0.946 and 0.980, respectively. However, NPP with the addition of PVA has 0.968 and 0.978 absorbance. The best concentration of NPP produced was 1 mm AgNO3
Study of Conceptual Change in Chemistry for Class XI Science High School Students
Get PDFVaried initial concepts can be an obstacle or support in understanding a new concept. The study of changes in students' chemical concepts was carried out on thermochemical material. This study aimed to examine changes in students' thermochemical concepts in each subject of high, medium, and low ability. Qualitative descriptive research with mixed methods was conducted on SMAN 1 Bumi Raya Morowali, Central Sulawesi students. The study began by giving an initial test to all students of class XI IPA 1 and 2, as many as 60 students, to obtain initial concept data and the basis for grouping subjects on each ability criterion (high, medium, and low). Every two people from each ability group in semi-structured interviews. Thermochemical material is re-taught using a metacognitive skill learning model and given a final test and interview to get concept data after learning to assess conceptual changes. Five concepts become variables in this study: the heat of reaction, enthalpy of reaction in a calorimeter, Hess's law, energy diagrams, and bond energies. The results showed that concept changes occurred in all high, medium, and low ability subjects. Changes in students' conceptions occurred in the concepts of the heat of reaction, reaction enthalpy, calorimeter, Hess's law, energy diagrams, and bond energy. The most significant conceptual change occurred in the subject of medium ability and low ability, namely the concept of bond energy
Chlorine Identification in Rice Samples through a Method Validation Approach using Cyclic Voltammetry with Platinum Electrodes
Get PDFDetermination of chlorine in rice samples with a method validation approach using cyclic voltammetry based on platinum electrodes has been conducted. This study aimed to determine whether the cyclic voltammetry method with platinum electrodes is acceptable and can be recommended for routine chlorine testing in the laboratory. The basis of the analysis is the reduction reaction of hypochlorite ions to chloride ions. The initial step taken by optimizing the electrolyte with the optimal electrolyte for testing is a pH 7 phosphate buffer solution. Method validation parameters consist of determining linearity, detection limit, quantitation limit, repeatability, recovery, and measurement uncertainty. The range of standard solutions used for testing was from 10 mg/L to 150 mg/L and analyzed at a rate of 0.1 V/s. Linearity is determined based on the calculation of the coefficient of determination (R2) of 0.998, while the limits for detection and quantization are 7.49 mg/L and 24.96 mg/L, respectively. Repeatability is determined by calculating the relative standard deviation with a result of 1.77% while for recovery it is obtained at 88.19%. The result of the chlorine content test for rice samples was 0.011% with a measurement uncertainty value of 0.0011%. The major contributor to uncertainty came from the concentration of the calibration curve plot of 87.91%
Method Validation and Estimation of Measurement Uncertainty in the Determination of Total Polyphenols Content in Land Spinach by UV-Vis Spectrophotometry
Get PDFLand spinach contains polyphenols which can be determined by the spectrophotometry method. Data on method validation and estimation of uncertainty measurement of polyphenols in land spinach are not yet available, so method validation and estimation of uncertainty measurement of polyphenol content determination were carried out using a UV-Vis spectrophotometer. The validation parameters of the tested methods include linearity, precision, accuracy, and LOD and LOQ. Analysis of total polyphenol content was carried out using the Folin-Ciocalteu method with the gallic acid standard. Based on the results of method validation, the equation of the line y = 0.7213x-0.0096 with a coefficient of determination (R2) is 0.9994. These results indicate that the correlation between standard concentrations of gallic acid and absorbance shows good linearity. Repeated measurements showed the average total polyphenol content and the estimated measurement uncertainty value was (3.0501±0,2886) mg/Kg GAE. The RSD percentage was obtained at 1.79% were the result entered the acceptance condition because it was ≤ 2%. Percent recovery was obtained at 81.50% and 85.66%, and the terms of acceptance range between 80-110%. The LOD and LOQ values obtained were 0.1024 mg/L and 0.3412 mg/L. Based on the data obtained, it can be said that the method used has good validity
Analysis Redox Reaction on Zinc-Coating Thickness Test in Metal Processing Industry of Small and Medium Enterprises
Get PDFThis study discusses the implementation of redox reactions on the thickness test of the galvanized (zinc-coated) layer using the JIS-H-0401 standard to help Small and Medium Enterprises (SMEs) industries. Some of the finished products go through the galvanizing process in the metal processing industry. Quality constraints, especially related to the thickness of the galvanic (zinc-coated) layer, have become an object that is less controlled because of the limitations of the test equipment used. This research uses an experimental method applied to one of its products: a flat washer with SPCC material and a thickness of about 2.20 mm. SPCC - SD material is classified as low carbon steel based on its carbon content. 5-unit flat washers were identified with sample codes A, B, C, D, and E. Flat washers have an internal diameter of 22.65 - 22.7 mm. In comparison, the outer diameter is between 43.75 - 43.80. The redox reaction process uses HCl (hydrochloric acid) with a concentration of 1 M, which is diluted with water (H2O). The zinc thickness test results show that the flat washer has an average thickness of 10.52 microns with a minimum and maximum thickness variation of 10.66 -10.72 microns