Jurnal Akademika Kimia
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Determination of Vitamin C and Metal Copper (Cu) Levels in Katokkon Chili (Capsicum chinense Jacq) Based on Maturity Level
Get PDFKatokkon chili is one type of chili grown mainly in the Tana Toraja district, and the people use this plant as a typical spice with variations colors from green, orange, and red. It is assumed that the plant is rich in vitamins and minerals. This study aims to determine the levels of vitamin C and copper metals in katokkon chili based on their level of maturity. Vitamin C and copper levels were determined by spectrophotometry. The results showed that the highest level of vitamin C was 23.52 and 5.12 mg/kg in both wet and dry orange chilies, while the highest copper level was found in green chili was 12.25 mg/k
Analysis of Students' Skills through Practicum on Reaction Rate Topic
Get PDFNational education emphasizes learning on assessing students' knowledge, attitudes, and skills. The development of skills aspect is not enough only relying on the learning in the classroom, but also necessary doing understanding outside the classroom such as practicum in the laboratory. The implementation of training allows students to practice their skills and help students understand the material taught in the class. This study aimed to describe the quality of students' skills on reaction rate topics through a practicum in grade XI at SMA Negeri 5 Palu. This type of research was a quantitative descriptive study with a one-shot case study design. Sampling was conducted by purposive sampling. The sample was Class XI Science 2 as the experimental class 1 with 23 students and Class XI Science 3 as the experimental class 2 with 25 students. The quality skill of students was measured by instruments in the form of observation sheets as the primary data. The data obtained through the observation sheet showed that the average percentage of all aspects of student skills in experimental class 1 was 74.81%, and in experimental class 2 was 74.05%. It indicates that the ten skills elements have emerged in the learning activities with a good category. This study concludes that the quality skill of grade XI students at SMA Negeri 5 Palu on learning reaction rate topic through practicum is a good category
A Simple Analyte Volatilization in Polytetrafluoroethylene (PTFE) Vessel for Spectrophotometric Determination of Boron
Get PDFA simple analyte separation through an in-situ volatilization system in a polytetrafluoroethylene (PTFE) container was carried out for boric acid analysis in a food product by spectrophotometry. Separation was conducted in two teflon containers divided into the reagents compartment (outer vessel) and sample compartment (inner vessel). System optimization was done by varying the curcumin content and ethanol: water ratio. The optimum condition of the volatilization system was achieved at a curcumin concentration of 0.1% and ethanol: water ratio of 3:1. LOD and LOQ measurements, respectively, gave a value of 0.0413 mg/L and 0.1088 mg/L. The established method was used to determine boric acid content in sausage products by UV-Vis Spectrophotometry at 555 nm. The boric acid concentration in food samples was found to be 0.913-3.518 mg/kg. The separating method through in-situ volatilization systems in a polytetrafluoroethylene (PTFE) container can be used for boric acid analysis in food samples
Softening Hard Water using Cocoa Shell Activated Charcoal
Get PDFCocoa pod shells contain 23-54 % cellulose, 1.14 % hemicellulose, and 20-27.95 % lignin. The high cellulose content in the cocoa pod shell has the potential to be further processed into adsorbents. Before being used as an adsorbent, activation using HCl solution was carried out to increase the adsorption power of the cocoa shell. This research was conducted to analyze the influence of adsorbent dose, pH solution, the efficiency of hard water reduction, and adsorption capacity on Ca2+ and Mg2+ ions. Adsorption of hard water ions was conducted by varying adsorbent doses of 1, 3, 5, 7, and 9 g and varying at the pH of 5, 6, 7, 8, and 9. Optimum condition achieved at the mass of 5 g with Ca2+ and Mg2+ ions adsorption efficiency of 85.4 and 18.31%, respectively. Optimum condition achieved at the pH of 9 with Ca2+ and Mg2+ ions adsorption efficiency of 61.54 and 49.11%, respectively. The highest Ca2+ and Mg2+ ions adsorption capacity was obtained at the adsorbent mass of 1 g with adsorption capacity respectively 4.05 and 0.54 mg/g. The highest Ca2+ and Mg2+ ions adsorption capacity was obtained at a pH of 9 with an adsorption capacity of 4.05 and 0.54 mg/g, respectively
Profile Secondary Metabolite Compounds and Antioxidant Activities of Stem Bark Jambu Mete (Anacardium occidantale L.) Extract
Get PDFOxidative stress is a condition in which the amount of free radicals and antioxidants in the body is not balanced, causing various diseases. One of them is a degenerative disease. Oxidative stress can be reduced by antioxidant compounds. Anacardium occidentale L. is a type of plant from the Anacardiaceae family. This plant is found in many trophic countries included Indonesia, and is believed to ward off degenerative diseases caused by oxidative stress. The purpose of this study was to analyze the activity of A. occidentale stem bark extract against DPPH radical inhibition (1,1-Diphenyl-2-Picrilhidrazil) and the profiling of secondary metabolites in their active fraction. The bark of A. occidentale was extracted by a gradient maceration method. The solvents used were n-hexane (nonpolar), ethyl acetate (semi-polar), and methanol (polar). The macerate was concentrated using a rotary vacuum evaporator, followed by DPPH radical inhibition analysis using a spectrophotometer. The most active extract was analyzed for chemical content by LC-MS/MS. The results showed that the extract of A. occidentale stem bark had antioxidant activity. Methanol extract obtained very strong and best antioxidant activity with an IC50 value of 47.13 ppm compared to ethyl acetate extract and n-hexane extract, which had IC50 values of 163.92 ppm and 501.72 ppm, respectively. Secondary metabolites that are thought to have antioxidant activity in the methanol extract of A. occidentale stem bark were epigallocatechin (EC) and epigallocatechin gallate (EGCG) compounds
Preliminary Study of Chemistry Knowledge Through Ethnochemistry Approaches to Communities
Get PDFThis research was a descriptive qualitative study using ethnographic methods. It aimed to determine the understanding and application of chemistry knowledge in the daily lives of Wiapore society, Marawola Barat district, through an ethnochemistry approach. Data obtained was in the form of an initial data inventory. These inventory data were then grouped into several data categories, namely categories related to food, beverage, and agriculture categories. The percentage value of each data was as follows, related to food 55.55%, related to drinks were 22.22%, and connected to agriculture were 22.22%. The results of this study are significant for local governments in taking policies relating to education for children and the Wiapore communit
Application of Discovery Learning Model to Improve the Understanding Concept of High School Students on Buffer Topic
Get PDFThis study aimed to describe the increase in understanding of students in class XI SMA 7 Palu on the buffer solution material after applying the discovery learning model. This type of research was pre-experiment with the design of one group pre-test-post-test. This study was conducted in two replication classes, namely, class XI MIA 1 as replication class 1 (n = 26) and class XI MIA as replication class 2 (n = 24). Testing of the data from research results data used descriptive statistical analysis of the understanding concept. The criteria for understanding the concept was good if the percentage of students who have the category of moderate, high, and very high is not less than 60%. The data results of analysis understanding of each concept obtained in the replication class 1. The concept of buffer, score 65. 38% increased to 96.15%. The concept of the properties of the buffer score 3.84% increased to 96.15%. The concept of acid-base buffer solution, score 0% increased to 92.3%. The concept of pH acid buffer, score 0% increased to 88.46%. The concept of pH base buffer, score 0% increased to 84.61%. In replication class 2, the concept of buffer solution score is 20.83%, increased to 91.66%. The concept of acid and base buffer solution, score 12.5% increased to 91.66%. The concept of pH base buffer, score 4.16% increased to 83.33%. The results of the analysis showed that there is an increase in understanding the good concept by applying the discovery learning model in the buffer material
Influence of the Guided Inquiry Learning Model Assisted by a Two-stay Two Stray towards Chemistry Learning Outcomes of High School Students
Get PDFThis study aimed to determine the influence of the guided inquiry learning model assisted by two stay two stray toward learning outcomes of students on chemistry at SMA 7 Palu. The type of study was Pre-experimental with a one-shot case study design. The sample was prepared using the purposive sampling technique with a sample consisting of Class XI Science 4 as the experimental class 1, and Class XI Science 2 as the experimental class 2. Both classes consisted of 28 students. The research instruments were the learning outcomes tests, student worksheets, and observation sheets that have been validated theoretically and empirically. Data of learning outcomes was analyzed using inferential statistical analysis with a prerequisite test: normality, homogeneity, and t-test hypothesis test (right side). The results showed that the average learning outcomes for experimental class 1 was 62.32, and for experimental class 2 was 50.29, with standard deviations of 12.58 and 12.05, respectively. Hypothesis test obtained tcount>ttable or 4.04 > 1.67, so H1 is accepted. The average learning outcomes of students in the experimental class 1 with guided inquiry learning model assisted by two stay two stray is higher than in the experimental class 2 with a guided inquiry learning model. Guided inquiry learning model assisted by two stay two stray influences learning outcomes of students at SMA 7 Palu
Applying Science Process Skills in Understanding Chemical Equilibrium Through Experiment
Get PDFStudents from Teachers College coming from various regions causes variations in the cognitive, affective, and psychomotor level. Some of them have a difficulty that leads to misconception in understanding the content in chemistry, particularly on chemical equilibrium. One of the ways to comprehend that content is by conducting experiments. This study aims to apply science process skills in understanding chemical equilibrium through the experiment method. This research also helps students in their experiments in which their ability is shaped to reach the level of application. Through experiment method, science process skill will develop and give a good response in giving action both in cognitive comprehension and ineffective as well as psychomotor level. The research method used is pre-experimental with a One-Group Pre-Post test Design. The result showed N-gain was 0.7, which classified high categories and science process skills showed good categories. The final result of this research was that students would be able to understand chemical equilibrium better by applying science process skills with an experiment
Pre-service Chemistry Teachers’ Mental Model of Colligative Properties for Nonelectrolyte Solutions
Get PDFMental models are representations that describe the understanding of the three levels of representation in chemistry, that is macroscopic, sub-microscopic, and symbolic. This study aims to obtain a general description of the mental model of pre-service chemistry teachers in the colligative properties of non-electrolyte solutions. The study was a descriptive research with 22 second-year FIP Chemistry Education students from Pelita Harapan University Tangerang. Data collection was carried out with research instruments in the form of diagnostic tests. The results of the study state that the average percentage level of representation is 67 % macroscopic level, 31% sub-microscopic level, and 72 % symbolic level. The results of this study indicate that students' understanding at the macroscopic and sub-microscopic level of the colligative properties of non-electrolyte solutions was low compared to chemical representations at a symbolic level. Meanwhile, the categories of mental models possessed by pre-service chemistry teachers in the topic of non-electrolyte colligative properties vary for each level of chemical representation. Based on the percentage at each level of representation, the mental model of chemistry teacher candidates with a symbolic model category is higher than the scientific model. The low mental model of the scientific model contributed to the understanding of the pre-service chemistry teachers that the concept of chemistry is not intact scientifically