Designing Calorimeter Made from Various Wastes

<p>A research has been conducted which aims to design a waste-based calorimeter as an alternative to measuring heat for chemistry practicum in schools. Research products developed through the steps of design-based research comprising the steps of analysis, design, and development. The resulting product is a waste-based calorimeter equipped with an automatic stirrer. The container to store the reagent solution on the calorimeter is made of Styrofoam, paper, plastic, melamine, PVC and bamboo. Optimization tool was conducted to determine the heat capacity of the calorimeter and the enthalpy of neutralization. The highest accuracy calorimeter value between 78-97%. Bamboo calorimeter has the highest accuracy value (97%). Styrofoam calorimeter has the lowest accuracy values (78%). Based on the results of the validation and feasibility test it can be concluded that the product is declared valid and feasible.</p>

Synthesis of Cinnamic Acid Based on Perkin Reaction Using Sonochemical Method and Its Potential as Photoprotective Agent

<p>Cinnamic acid plays a vital role in the synthesis of other important compounds and as a precursor for the synthesis of commercial cinnamon esters used in perfumery, cosmetics, and pharmaceutical industries. The aim of this research is to synthesize cinnamic acid using sonochemical methods. Cinnamic acid was synthesized using Perkin reaction by reacting 0.05 mole of benzaldehyde with 0.073 mole of acetic acid anhydride and 0.03 mole of sodium acetate as a catalyst in the Erlenmeyer flask and then the mixture was put in a sonicator for 60 minutes at 70 ^oC. The synthesized compound was tested organoleptic properties, and the melting point was measured. The chemical structure was elucidated using FT-IR, H-NMR, and ¹³C-NMR. The photoprotective activity was examined from its antioxidant and SPF values. The synthesized compound was found in the form of a shiny white fine crystal which had distinctive odor with a yield of 4.98% and the melting point was found at 133^oC. In the structure elucidation using FT-IR (the aromatic ring absorption at the wave number 1580 cm^-1 -1600 cm^-1. The wave number 1625 cm^-1is an aromatic conjugated alkene group, while wave number 1689.4 cm^-1is a carbonyl group. The wave number 2500 cm^-1– 3250 cm^-1is an OH carboxylic acid group) , H-NMR (7.410 (<em>m</em>, 5H, Ar-H); 7.425(<em>t</em>, 1H); 7.572 (<em>d</em>, 1H); 8.057 (d, 1H,C=CH) and ¹³C-NMR (129.309 ppm; 130.998 ppm; 134.58 ppm; 170.017 ppm) showed that when compared with the standard compound as the reference, the synthesized compound was confirmed to be cinnamic acid. The antioxidant activity test showed that at the concentration of 20 ppm the synthesized compound was able to reduce free radicals by 46.69%. This finding showed that the synthesized compound had antioxidant activity.</p>

Using Think-Pair-Share to Develop Students' Social and Emotional Competencies in Chemistry Learning

<p>The aim of this study was to analyze students' social and emotional competencies through the integration of Think Pair Share (TPS) and a Social and Emotional Learning (SEL) approach to topics related to Ac­ids and Bases. Social and emotional learning (SEL) is the process through which children and adults under­stand and manage emotions, set and achieve positive goals, feel and show empathy for others, establish and maintain positive relationships, and make responsible decisions.. The study involved thirty-five 11th grade students in one of private school in Jakarta and was conducted between January and April, 2017. A qualitative methodology was employed to analyze students’ social and emotional competencies using inter­views, classroom observations, reflective journals, and student worksheets. The application of a SEL ap­proach was carried out by integrating it with a TPS strategy. In the <em>Think</em> stage students were given the opportunity to explore their understanding of acids and bases and to solve problems individually. In the<em> Pair</em> stage they could communicate their insights to the group, and in the <em>Share</em> stage they had occasion to present their group perspectives and respond to others. The five social and emotional competences found in this study were; self awareness, self management, social awareness, relationship management, and re­sponsible decision making. Self awareness was demonstrated by understanding a student’s abilities, their needs, and their self- confidence. Self management was indicated by a student’s ability to manage pressure, plan strategies, and seek help. Social awareness competencies were analyzed through the development of students' attitudes to diversity and how they demonstrated care for friends. Relationship management com­petencies were identified by observing a student’s ability to manage friendships, how they overcame differ­ences, and whether they provided assistance to each other. The responsible decision making competency was determined by observing how students made decisions when trying to solve a problem and whether they were able to plan a strategy when facing pressure. Whilst integrating SEL the researchers were chal­lenged by the need to empower students, encourage teachers to stimulate students’ social and emotional competencies, and to manage time constraints. Integrating SEL into chemistry learning provided opportuni­ties for students to develop their social and emotional competencies through independent thinking activities, group discussions, and presentations to their peers.</p>

Potential of Water Extract of The White Frangipani (Plumeria acuminate) and Hibiscus (Hibiscus tiliaceus) Leaves Powder as Textile Natural Dyes

<p class="Default">Synthetic dyes have a high environmental impact, especially on waters. The use of natural dyes for textiles provides new hope for ecological improvement. This article is to find out the yield of water extract of white frangipani (<em>Plumeria acuminate</em>) and hibiscus (<em>Hibiscus tiliaceus</em>) leaves-powder, as well as to find out whether the water extracts have potential as textile natural dyes. Natural dyes must have a good quality of fastness. For this reason, the color fastness tests for washing with a launder meter and colorfastness against rubbing with a crock meter are performed. Colorfastness is assessed by comparing color changes to washing with grayscale and color changes due to staining on fabric with staining scale. The rubbing test is carried out on the wet and dry cloth. Cotton and polyester fabrics are samples that will be colored. Fixers used to bind dyes are Al₂(SO₄)₃, CaCO₃, and FeSO₄.H₂O. The results show that the water extraction of hibiscus and white frangipani leaves powder gave a yield of 11% (w/w) and 27 % (w/w), respectively. The test of colorfastness against washing showed that both water extract of the white frangipani dan hibiscus leaves has a pretty good average quality in staining scale but less in grayscale. The test against rubbing shows that the type of fixer used affects the quality of the colorfastness, but in general, the water extract of white frangipani leaves gives better quality as a potential of natural dye than hibiscus leaves</p>

Influence Comparison of Precursors on LiFePO4/C Cathode Structure for Lithium Ion Batteries

<p>Electricity is the most energy demanded in this era. Energy storage devices must be able to store long-term and portable. A lithium ion battery is a type of battery that has been occupied in a secondary battery market. Lithium iron phosphate / LiFePO₄ is a type of cathode material in ion lithium batteries that is very well known for its environmental friendliness and low prices. LiFePO₄/C powder can be obtained from the solid state method. In this study the variables used were the types of precursors : iron sulfate (FeSO₄), iron oxalate (FeC₂O₄) and FeSO₄+charcoal. Synthesis of LiFePO₄/C powder using Li:Fe:P at 1:1:1 %mol. Based on the XRD results, LiFePO₄/C from FeSO₄+charcoal shows the LiFePO₄/C peaks according to the JCPDS Card with slight impurities when compared to other precursors. XRD results of LiFePO₄/C with precursors of FeSO₄ or FeC₂O₄ shows more impurities peaks. This LiFePO₄/C cathode is paired with lithium metal anode, activated by a separator, LiPF₆ as electrolyte. Then this arrangement is assembled become a coin cell battery. Based on the electrochemical results, Initial discharge capacity of LiFePO₄/C from the FeSO₄ precursor is 19.72 mAh/g, while LiFePO₄/C with the FeC₂O₄ precursor can obtain initial discharge capacity of 17.99 mAh/g, and LiFePO₄/C with FeSO₄+charcoal exhibit initial discharge capacity of 21.36 mAh/g. This means that the presence of charcoal helps glucose and nitrogen gas as reducing agents.</p>

Influence of Upwelling in the Southern Waters of Java on CO2 Concentration in Kototabang, Agam District West

<p>Absorption of atmospheric CO₂ by the sea through two processes, namely solubility pumps and biological pumps. This study aims to determine the effect of upwelling in the southern waters of Java on atmospheric CO₂ concentrations in Kototabang. The data used are in situ CO₂ concentration, sea surface temperature and chlorophyll-a concentration from 2004-2016. The method used was descriptive analysis. The results showed that upwelling that occurred during JJA-SON caused a decrease in sea surface temperature to 26.8 °C and 27.1 °C respectively, as well as an increase chlorophyll-a concentration to 2.03 mg/m³ and 2.19 mg/m³. In both seasons CO₂ concentration in Kototabang dropped to 385.8 ppm and 385.4 ppm. Meanwhile, when there was no upwelling during DJF-MAM, sea surface temperatures rose to 28.8 °C and 29.0 °C, and chlorophyll-a concentration dropped to 0.32 mg/m³ and 0.54 mg/m³. CO₂ concentration in DJF and MAM increased to 386.3 ppm and 386.5 ppm. Based on these results it is known that when upwelling occurs, CO₂ concentration decrease and vice versa.</p>

Sonochemical Synthesis of Ethyl Cinnamate

<p>This research aimed to determine the yield of ethyl cinnamate synthesized by the sonochemical method and its potency as a sunscreen agent. Ethyl cinnamate was synthesized from cinnamic acid and ethanol with concentrated sulfuric acid as catalysts assisted by ultrasonic waves. The Identification of compounds was carried out by infrared spectrophotometry and gas chromatography-mass spectroscopy. Synthesis of ethyl cinnamate resulted in the form of clear yellow liquid with a fragrant aroma of a cinnamon ester with a 96.61% yield. Identification by an infrared spectrophotometer showed many functional groups of ethyl cinnamate. Identification by GC-MS was given a relative abundance of 98.96%. The product of synthesis had SPF number 4.769 at 10 ppm used Mansur Equation. Based on this research, it concluded that it has potential as a sunscreen agent. The sonochemical method provides an excellent yield of ethyl cinnamate.</p>

QSAR Modeling of Compounds Derived from 1,2,3-Triazolopiperidine as DPP-4 Enzyme Inhibitors Using Semiempirical AM1

<p>This study aims to model the derived compounds of 1,2,3-triazolopiperidine using sem­iempirical method AM1 and determine the further derivation with the better IC₅₀ values against DPP-4 enzyme theoretically. This research employed ChemDraw Pro 12 software for for 2D struc­tural drawing, Hyperchem 8.0 for 3D modelling, and MLR statistical analysis for modeling QSAR equations. The semiempirical method was likely to be the appropriate platform to apply because the correlation coefficient of H¹NMR chemical shift between theoretical and actual value is rela­tively close, 0.8891. The multilinear regression analysis produced 4 equation models where the best one is equation 4 as detailed below:” IC₅₀ = 875,5116 + (-7400,27*qH35) + (-0,00133* Eat.is) + (-3230,72* qN23) + (3,30277* µ)” n = 25; r² = 0,594; <em>Adjusted r²</em>= 0,486; PRESS = 1,2× 10⁴^.Finally, the theoretically promising substituent was -CN possessing IC₅₀ value = 1.61 nM. </p>