Activated carbon is a prominent adsorbent for removing hazardous chemicals, and abundant natural resources allow the production of activated carbon utilizing various sources of biomass. This study aims to investigate the capacity of carbon prepared from Coffea arabica grounds waste in adsorbing methanal. The carbon from used coffee grounds was activated using ZnCl2 30% in a microwave at 800 Watt for 10 minutes. The characteristics of activated carbon investigated include moisture content (1.47%), ash content (4.74%), and iodine number (803.7 mg/g). The study of methanal adsorption was carried out under the following conditions: adsorbent mass (gram) (0.5, 1, and 1.5), contact time (minute) (20, 50, and 80), methanal concentration (ppm) (5, 10, and 15), and pH (2, 5 and 8). The optimum conditions for adsorption were studied using a central composite design (CCD), and the data were analyzed using Minitab 16 software. The adsorption was optimally achieved at 1.50 grams of adsorbent, 58.18 minutes of contact time, 10.15 ppm of methanal concentration, and pH of 2. The percent of adsorption of methanal at optimum conditions was 54.31%. The adsorption of methanal by activated carbon from Coffea arabica ground waste fit best with the Freundlich isotherm model (R² = 0.9918), indicating multilayer adsorption

The study objective was to determine the validity and reliability of the test items used to measure understanding of multiple representations. For this purpose, quantitative methods are applied. Participants were first-year students of the Chemistry Department, Education and Teacher Training Faculty, Syiah Kuala University, who took the Basic Chemistry course I (specifically solubility, redox, and hydrocarbons). The test was followed voluntarily. Before determining the validity and reliability of each test, the Multiple Representation Understanding Test (MRUT) was developed, which was conducted in five stages. MRUT contains 20 items, and its validity is determined using Pearson Product Moment (PPM). Valid test items are nine where r coun t 0.3128-0.7145. The nineitem tests are reliable, and Cronbach alpha ranged from 0.701 to 0.769 (moderate-high).

One of the concerns in the learning process is the meaning of writing mnemonics to help students memorize chemistry concepts. The research aimed to correct mnemonics in learning presentation by prospective chemistry teachers' students to be meaningful. The research used constructive design and qualitative methods. The researcher was the main instrument for the microteaching course. Data were collected through observation, focus group discussions (FGD) based on cognitive conflict, and documentation analysis. The results showed that it was found that two prospective chemistry teachers’ students from different groups presented the same mnemonic with less meaningful. The mnemonic was used to memorize the halogens (group 17 of the periodic table). The less meaningful mnemonic generally comes from social media. Based on the group discussion, the students of prospective chemistry teachers obtained 18 mnemonics with meaningful values.Prospective teachers must be able to improve mnemonics in learning to make it more meaningful, one way being to integrate ethnoscience aspects. It was suggested that there should promote creativity in developing learning that encourages positive attitudes to strengthen character education.

Chemical misconceptions occur in almost all topics. Identification of chemical misconceptions has been carried out on students, students and even teachers. Chemical concepts are interrelated, so misconceptions at the primary level have the potential to cause misconceptions in the next concept. This study aims to identify misconceptions held by prospective chemistry teachers practicing basic teaching skills and overcome them through cognitive conflict strategies. This research is a naturalistic case study with an interpretive paradigm framework. Research is carried out naturally (natural setting) following the ongoing lecture program. The research was conducted during the even semester of the 2021/2022 academic year with 32 meetings for two classes. The research participants comprised 25 students (2 classes) taking microteaching courses. As the main instrument, the researcher is a microteaching subject with more than ten years of teaching experience. Data were collected using observation and interview methods with a cognitive conflict strategy framework. The results showed many misconceptions, including ionic bonds, ionization, and the formula for determining the pH of a buffer solution. Four prospective chemistry teachers experienced this misconception when practicing basic teaching skills. The correction results showed that 3 out of 4 students managed to correct the misconceptions that had been experienced before. One misconception is resistants. Based on the study results, it is recommended that a teacher or instructor pay attention to the misconceptions that occur and immediately overcome them as soon as possible.

Research has shown that most chemistry teachers have misconceptions about covalent bonding. This study investigates whether the cognitive conflict interview technique could persuade teachers to revise their possible misconceptions of covalent bonding. Eight chemistry teachers from different schools participated in this study. Two validated instruments, cognitive conflict technique inter-view guidelines and the open-ended covalent bonding test, were employed for data collection. The results showed that cognitive conflict interviews could facilitate respondents to overcome their misconceptions about covalent bonding. Five of the eight respondents experienced a conceptual change from misconceptions to scientific conceptions, and three others experienced a partial conceptual change. Six concepts previously a source of misconceptions was eliminated and turned into a scientific concept instead. Of the 46 cases of misconceptions, 41 cases turned into scientific conceptions. The result of this study serves as an initial perspective for exploring the effectiveness of cognitive conflict interviews more broadly.