Jurnal Akademika Kimia
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The Levels of Student Questioning and Critical Thinking Ability in Acid-Base Topics and Correlation with Learning Outcomes
Get PDFAcid-base material is often considered difficult for students because it is abstract, leading to misconceptions and poor learning outcomes. The ability to ask questions reflects cognitive engagement and is closely related to the critical thinking required to understand abstract concepts. Therefore, it is important to examine this skill to obtain evidence of its role in improving chemistry learning outcomes and as a consideration for teachers in determining the appropriate learning process. This study aims to analyze students' questioning skills and critical thinking abilities in acid-base learning and examine the relationship between these skills and students' learning outcomes. A quantitative descriptive approach was employed and conducted at SMAN 1 Dampal Utara. The research subjects comprised 30 students, including 17 females and 13 males. Male students. The sample was selected using a purposive sampling technique. The instruments used for data collection included the questioning skills test and the critical thinking skills test. The results indicated that students’ questioning skills were categorized as moderate with a percentage of 57.5 %, similarly, their critical thinking abilities also fell into the mild category with a rate of 48.33 %. Correlation analysis revealed a significant relationship between questioning skills and learning outcomes (r= 0.386;α=0.035). Meanwhile, the relationship between critical thinking and learning outcomes was shown to be insignificant (r= 0.225;α= 0.173). These findings suggest that questioning skills can contribute to optimal learning outcomes
Epoxidation of Eugenol from Clove Oil (Syzygium aromaticum) Using H₂O₂ Oxidizer and H₃PO₄ Catalyst
Get PDFClove oil (Syzygium aromaticum) contains 80–90% eugenol. Eugenol is a pale yellow liquid with several active functional groups, such as hydroxyl, aromatic rings, and allyl groups, which allow it to be modified to produce various eugenol derivative compounds. This study aims to characterize eugenol epoxy resin synthesized from clove oil eugenol using hydrogen peroxide (H₂O₂) and phosphoric acid (H₃PO₄) as a catalyst. The resulting eugenol epoxide was in the form of a yellowish-white gel with a distinctive clove aroma. It was soluble in benzene and chloroform but insoluble in ethanol. FTIR analysis showed that the epoxy compound contained an ether group (C-O-C) at absorption peaks of 1266.07 cm⁻¹ to 1018.66 cm⁻¹, a hydroxyl group (─OH) at 3347.08 cm⁻¹, a methyl group (-CH₃) at 1470 cm⁻¹ to 1350 cm⁻¹, an alkene group (C=C) at 1637.39 cm⁻¹, and a vinyl group at 910.2 cm⁻¹
A Study Compares The Effectiveness of Hydrochloric and Sulfuric Acids in Hydrolyzing Jackfruit Seeds into Bioethanol
Get PDFNorth Sumatera Province, known for its jackfruit production, presents an opportunity to explore jackfruit seeds as a viable bioethanol feedstock. The province’s diverse agricultural commodities generate substantial agricultural waste, currently primarily used as fertilizer. This research aims to diversify waste utilization by focusing on jackfruit, a prominent commodity in North Sumatera, and its potential as a bioethanol feedstock. Given the scarcity of fossil fuels, exploring renewable energy sources, such as bioethanol derived from agricultural waste, is crucial. Identifying accessible sources within regions is vital. Converting jackfruit seed starch into bioethanol requires hydrolysis. This paper compares hydrochloric and sulfuric acid for bioethanol production. Qualitative testing confirmed the presence of bioethanol from both acids. The density of bioethanol produced using hydrochloric acid was 0.825 g/mL, 3.4% higher than the Indonesian standard value. Similarly, the density of bioethanol produced using sulfuric acid was 0.894 g/mL, 12% higher than the standard value. The viscosity of bioethanol produced using hydrochloric acid was 1.02 cp, 12% lower than the standard value. In contrast, bioethanol produced using sulfuric acid had a viscosity of 1.04 cp, 11% lower than the standard value. FTIR spectra of bioethanol treated with hydrochloric acid showed five prominent peaks: 3339.88 cm-1 (OH), 2953.35 cm-1 (-CH), 1643.79 cm-1 (-C-C), 1450.75 cm-1 (-CH3), and 1014.17 cm-1 (-CO). FTIR spectra of bioethanol treated with sulfuric acid showed only two major peaks at 3339.46 cm-1 and 1635.42 cm-1, both corresponding to -OH and -CH. The NMR spectra show three distinct peaks. In ethanol’s proton NMR spectrum, the first doublet at 1.71 and 1.61 ppm is the methyl group protons. The second peak at 2.02 ppm is the hydroxyl group proton. The third doublet at 3.59–3.62 ppm is the methylene group protons. All methods indicate that hydrochloric acid is a more effective hydrolytic agent than sulfuric acid
Effectiveness of Problem-Based Learning with Dr Stone Animation on Grade XI Students’ Acid-Base Learning Outcomes
Get PDFThe background of this research is low student performance in the topic and the need for an innovative, interactive, and contextual learning approach. This study aims to examine the effectiveness of the Problem-Based Learning (PBL) model using Dr Stone's animation media on students' learning outcomes in the acid-base topic for Grade XI students at SMA Negeri 1 Sirenja. The problem addressed in this research relates to how to improve student learning outcomes and engagement through the integration of contextual and technology-based media. The research employed a pre-experimental design with a one-group pre-test and post-test on a single experimental class consisting of 30 students. The instruments used included Lesson Plans (RPP), Student Worksheets (LKPD), Dr Stone animation media, and a multiple-choice learning outcome test consisting of 15 validated questions, reviewed and approved by expert validators. The validation results showed that all instruments were valid and appropriate for use. Student learning outcomes were analysed using the N-Gain score to measure the improvement after learning. The average N-Gain score was 0.7331 (73.31%), placing it in the moderately effective category. The average difference between pre-test and post-test scores was 37.10 points, indicating a significant improvement in student learning outcomes. Most students experienced substantial learning gains after participating in problem-based learning supported by animation media. This study demonstrates that combining the Problem-Based Learning (PBL) model with Dr Stone's animation media effectively improves student learning outcomes. Furthermore, this study supports the learning process by incorporating a contextual and interactive approach that fosters students’ motivation, deepens their conceptual understanding, and promotes active involvement in chemistry lessons. It also offers valuable guidance for teachers on applying technology-integrated, student-centred teaching strategies in science education
Characteristics of Critical Thinking Skills of Class XI Senior High School on Stoichiometry Material
Get PDFThis study aims to describe the characteristics of students’ critical thinking skills in the Stoichiometry material of class XI SMA Negeri 1 single. This type of research is descriptive quantitative. The sample of this research was all students of class XI SMA Negeri 1 Sindue, which consisted of 3 classes, namely class XI MIA 1, XI MIA 2, and XI MIA 3. The data in this study were obtained through a test of students' critical thinking skills in the form of essays with as many as five items. Three essential thinking indicator items are interpretation, analysis, and inference. The results of data analysis for students' critical thinking skills for indicators of interpretation, analysis, and inference showed that class XI MIA 1 obtained the percentage results for the interpretation indicator 40,5 % in the low category, the analysis indicator obtained by the percentage of 35 % was included in the low category, and indicator inference obtained a percentage of 17 % who are in the very low category. Class XI MIA 2 obtained the percentage result on the interpretation indicator 46 %, which is in the low category. In comparison, the analysis indicator obtained a percentage of 59.5 % who are in the low category, and indicators inference obtained a percentage of 25,5 % who are in the low category. Whereas in class XI MIA 3, the percentage of interpretation indicators was 44 % in the low category, the analysis indicators obtained a percentage of 57,5 % who were in the low category. The inference indicator obtained 23,5 % who were in the very low category. Based on the research results at these schools, it can be seen that the critical thinking skills of class XI students of SMA Negeri 1 Sindue are still very low
Comparison of Maceration and Soxhlet Extraction Methods on Flavonoid Contents from Papaya (Carica papaya)
Get PDFThe papaya plant offers numerous benefits. Each part of the papaya plant has its benefits, starting from the fruit, stem, roots, flowers, and leaves. Livestock Medicine confirmed the presence of at least 22 types of bioactive compounds. The papaya plant contains active compounds that act as antioxidants, including flavonoids. This research aims to compare maceration and Soxhlet extraction methods on the flavonoid content of papaya (Carica papaya) leaf extract as measured using a UV-Vis spectrophotometer. The methods used to separate flavonoid levels are maceration and Soxhlet extraction. Based on the research that has been carried out, it was found that two treatments were carried out in the maceration method: the first treatment was with 70 % ethanol solvent, namely 36.6 mg / 100g or 3.66 %, for 96 % ethanol solvent, namely 77.6 mg / 100g or 7.76 %. Two treatments are also carried out in the Soxhlet method: 70% ethanol (33.6 mg/100g, 3.36%) and 96% ethanol (92.6 mg/100g, 9.26%). These results indicate that Soxhlet extraction is the most effective method for producing flavonoids in papaya leaf extract, as the levels obtained are higher than those obtained by maceration
Determination of Citric Acid Level in Starfruit (Averrhoa bilimbi L.) and Starfruit Raisins
Get PDFCitric acid is one of the plants in Indonesia that has many benefits in various fields, especially in the industry. This study aims to determine the levels of citric acid in starfruit (Averrhoa Bilimbi L.) and starfruit raisins in Oti Village, Sindue Tobata District, Donggala Regency. The analytical method used to determine the levels of citric acid is alkalimetric titration. The sample used in this study came from Oti Village, Sindue Tobata District, Donggala Regency. The percentage results showed that the levels of starfruit citric acid were 6.363 %, and the starfruit raisins were 4.703 %
Analysis of Metal Content in Rocks Using X-Ray Fluorescence (XRF)
Get PDFRocks in mining have different types and levels of metal from one another. This study aims to determine the levels of metals present in rocks found in illegal mining areas in the Dongi-Dongi region. The parameters tested are the type of metal contained in rocks from unlawful mining in the Dongi-Dongi area and the amount of metal content in rocks from illegal mining in the Dongi-Dongi area. The results showed that the metals contained in the five rock samples from gold mining in Dongi - Dongi were, respectively, iron (Fe), potassium (K), silicon (Si), calcium (Ca), titanium (Ti), arsenic (Ar), zirconium (Zr), manganese (Mn), rubidium (Rb), niobium (Nb), molybdenum (Mo), indium (In), strontium (Sr), tin II (Sn), and rubidium (Ru) with the highest metal percentage found in the fifth rock sample (E), namely iron (Fe) at 62.89 % and potassium (K) at 54.7 %. The high content of iron and potassium in Dongi-Dongi mining rocks has the potential to be utilized by the community, as these metals are widely used in various industrial fields
Analysis of Bioaccumulation of Mercury (Hg) in Yuyu Crabs (Parathephusa Convexa) in The Janja River, Malomba Village, Dondo District, Tolitoli Regency
Get PDFThe phenomenon of environmental damage due to unlicensed gold mining activities harms aquatic ecosystems. Mercury (Hg) waste from the mining process has the potential to cause bioaccumulation in aquatic biota such as fish and crabs, which can lead to mercury contamination in the human body through the food chain. The bioaccumulation process can also produce toxic organic compounds that harm human health. Therefore, this research aims to determine whether mercury bioaccumulation occurs in yuyu crabs in the Janja River, Malomba Village, Dondo District, Tolitoli Regency, due to gold mining activities. The method used in the research is the calibration curve method with Cold Vapor Atomic Absorption Spectrophotometry (CV-AAS) analysis at a wavelength of 253.7 nm. The results obtained from this research indicate that bioaccumulation has occurred in yuyu crabs that live in the Janja River. The highest accumulated mercury metal levels were obtained at upstream locations with an average of 5.24 ppb; the lowest was in the midstream, which is 1.53 ppb. At the downstream location, it has a mercury concentration of 4.53 ppb. So it shows that the mercury contamination in the yuyu crab samples is below the quality standard threshold, Indonesian National Standard No. 7387 of 2009, for the heavy metal mercury in other types of crabs and crustaceans is 1.0 ppm or 1000 ppb
Protein Content and Organoleptic Test Central Sulawesi Pumpkin Seed Tempeh (Cucurbita moschata) for Learning Resource
Get PDFThe yellow pumpkin (Cucurbita moschata) is a plant that readily adapts to diverse soil conditions; however, the utilization of its seeds remains restricted. Despite possessing a relatively high protein content crucial for growth and energy, it can serve as an alternative raw material for tempeh production. This study intends to generate yellow pumpkin seed tempeh in compliance with SNI 3144:2015 organoleptically, assess variations in the protein content of yellow pumpkin seed tempeh from three distinct regions in Central Sulawesi, and produce a Student Worksheet as an alternative resource for chemistry education through expert lecturer validation. This research employs a quantitative methodology utilizing the Kjeldahl analysis technique to ascertain protein concentrations across three phases: destruction, distillation, and titration. Furthermore, a sensory evaluation was conducted by 20 panelists to analyze the texture, color, flavor, and scent of yellow pumpkin seed tempeh. The resultant tempeh has favorable organoleptic properties, achieving an average preference score of 4, characterized by uniform white coloration, a distinctive tempeh aroma, and a dense texture. Protein content research revealed that tempeh from Palu City had the most significant protein concentration at 24.5 %, followed by Palolo District at 23.91 %, and North Lore District at 20.41 %, suggesting the impact of environmental factors on the nutritional composition of the manufactured tempeh. According to SNI 3144:2015, the visual characteristics of yellow pumpkin seed tempeh and its protein content conform to the established quality criteria. The findings of this study were presented as Student worksheets, which achieved a validity rate of 85 %, indicating its high suitability as a learning resource. This research enhances the application of yellow pumpkin seeds as a nutritious food source and fosters the creation of engaging and novel educational materials