Reaction Formula Research Articles

고교학점제에서 과학 선택 과목의 경향성 분석

Objectives This study investigated and analyzed the tendency of students to choose subjects and the tendency of chemical academic achievement according to science subject selection in the high school credit system. Methods For six months, from March to August 2020, 339 sophomores of S High School located in Gyeongnam were surveyed and analyzed for their perception of subject selection. Among them, a questionnaire was devel-oped to find out the perception of the content of chemistry subjects, and a questionnaire was conducted on 78 people who agreed to participate in the study. In order to analyze the tendency of chemical academic achievement according to science subject selection in the high school credit system, descriptive statistics, cross-analysis, and nonparametric tests were performed with the SPSS 28 program. Results Students selected many of the science elective subjects in the order of 'Chem-Phys-Bio,' 'Chem-Phys-Earth,' and 'Chem-Bio-Earth.' In the content and concept of the Chemistry I subject, students were found to have difficulty understanding concepts such as 'mole,' 'chemical reaction formula,' 'orbital,' etc., and the 'Chem-Phys-Earth' subject group was found to have the most difficulty in understanding the concept of 'mole.' In addition, in the comparison of achievement by elective subject group, the 'Chem-Phys-Bio' subject group showed the highest chemical academic achievement and the 'Chem-Phys-Earth' subject group showed the low-est achievement. Conclusions In the high school credit system, students chose the Science I course independently, but many stu-dents were found to have insufficient understanding of the basic concept of Chemistry I. Therefore, in terms of understanding the concept of chemistry, it is essential to design a teaching-learning process by level so that stu-dents can better understand the basic concept of Chemistry I in the high school credit system.

Flow Effects on the Morphology of Silicon Materials Produced in a Gas Phase Reaction of SiCl<sub>4</sub>

Chemical reaction formula does not provide information on size and morphology of formed solids. In this talk, we introduce our recent results on process-dependent changes in size and morphology of silicon solids produced via zinc reduction of SiCl4. Silicon whiskers, microparticles and nanowires form in the reaction, in which zinc vapor reduces SiCl4 and zinc droplets catalyse crystallization of silicon. Flow of gases in a reactor and temperature of substrate affect solidification processes of silicon. Effects of there factors on the formation of silicon whiskers and nanowires are discussed using both experimental results and numerical analysis.

초등 과학 교과서의 화학 반응에 대한 초등예비교사들의 내용 이해에 관한 연구 : 2015 개정 교육과정 중심으로

This study investigated the analysis of chemical reactions in the 2015 revised curriculum science textbook and the questions of six chemical reactions through questionnaires. The results are as follow. The subjects of this study were 54 students in senior who are pre-service elementary teachers. After experiencing all the experiments in elementary science textbooks for one semester, six chemical reactions were selected from the science textbooks. The six research questions were: writing reaction formulas, matching coefficients, mass relationship, state of matter, thermal relationship, kind and types of reaction. I found out the level of understanding through the questionnaire. In writing the chemical reaction formula, the confirmation of the chemical reaction and reason was answered by looking at the basic theoretical knowledge and the phenomenon that appeared. As for the coefficient of the chemical reaction equation, the incorrect answer rate was much higher than the correct answer rate due to the lack of a concept of the balanced equation. As for the mass relation, more than half of them are generally aware of it because of the theoretical knowledge that mass is conserved. But there were many students who recognized that mass could change as the state of matter changes. As for the state of matter, It was difficult to distinguish the states of reactants and products during chemical reactions so about half of the students recognized the state of matter. As for the thermal relationship, most students recognized that energy is involved in a chemical reaction from the theoretical knowledge and the phenomena that appeared. As for the kinds of reacions, most of the students were familiar with them but did not know well about the types of reaction. Therefore, the lack of knowledge about chemical reactions can affect the classes in the future education field, so it is important to acquire knowledge from the college subjects and individual efforts.

Free radical degradation in aqueous solution by blowing hydrogen and carbon dioxide nanobubbles

The main findings are the hydroxyl radical scavenging and the superoxide anion diminishing by mixing the carbon dioxide (CO2) nanobubbles after hydrogen nanobubble blowing in water and alcohol aqueous solution. The nanobubbles produce the hydroxyl radical by ultrasonic waves, changing the pH and catalyst and so on, while the nanobubble is very reactive to scavenge free radicals. In this research especially hydrogen (4% H2 in argon) and CO2 nanobubbles have been blown into hydrogen peroxide (H2O2) added pure water, ethanol, and ethylene glycol aqueous solution through a porous ceramic sparger from the gas cylinder. The aqueous solutions with H2O2 are irradiated by ultraviolet (UV) light and the produced hydroxyl radical amount is measured with spin trapping reagent and electron spin resonance (ESR). The CO2 nanobubble blowing extremely has reduced the hydroxyl radical in water, ethanol, and ethylene glycol aqueous solution. On the other hand, when H2 nanobubbles are brown after CO2 nanobubble blowing, the hydroxyl radical amount has increased. For the disinfection test, the increase of hydroxyl radicals is useful to reduce the bacteria by the observation in the agar medium. Next, when the superoxide anion solution is mixed with nanobubble containing water, ethanol, and ethylene glycol aqueous solution, H2 nanobubble has reduced the superoxide anion slightly. The water containing both CO2 and H2 nanobubble reduces the superoxide anion. The less than 20% ethanol and the 30% ethylene glycol aqueous solution containing CO2 nanobubbles generated after H2 nanobubble blowing can diminish the superoxide anion much more. While the H2 nanobubble blowing after CO2 nanobubble blowing scavenges the superoxide anion slightly. The experimental results have been considered using a chemical reaction formula.

Solid‐state synthesis and characterization of cobalt blue core‐shell pigment particles

AbstractCobalt blue is one of the most chemically and thermally stable blue pigments. However, cobalt is scarce and expensive. To minimize the use of cobalt and reduce production costs and toxicity, cobalt blue core‐shell pigments were synthesized by a solid‐state method, which is cheaper than a liquid‐phase reaction. Small cobalt hydroxide particles and large α‐alumina particles, in various ratios, were used as the starting materials. The dry mixed powders were calcined at 1200°C for 2 hours. Elemental mappings of the surfaces and cross sections of the synthesized particles showed that the cobalt blue had a core‐shell structure. X‐ray diffraction patterns showed that the synthesized cobalt blue consisted of an α‐alumina core and a cobalt aluminate shell. The color tone of the synthesized cobalt blue was evaluated from the lightness (L*) and chroma (C*) values. The color tone of the cobalt blue synthesized in this study was almost same as those of commercially available samples although the cobalt molar fraction was lower than the stoichiometric ratio (Co/(Co + Al) = 0.33, Co/Al = 0.5) which was calculated from the chemical reaction formula.

Solving the Schrödinger equation of atoms and molecules: Chemical-formula theory, free-complement chemical-formula theory, and intermediate variational theory.

Chemistry is governed by the principle of quantum mechanics as expressed by the Schrödinger equation (SE) and Dirac equation (DE). The exact general theory for solving these fundamental equations is therefore a key for formulating accurately predictive theory in chemical science. The free-complement (FC) theory for solving the SE of atoms and molecules proposed by one of the authors is such a general theory. On the other hand, the working theory most widely used in chemistry is the chemical formula that refers to the molecular structural formula and chemical reaction formula, collectively. There, the central concepts are the local atomic concept, transferability, and from-atoms-to-molecule concept. Since the chemical formula is the most successful working theory in chemistry ever existed, we formulate our FC theory to have the structure reflecting the chemical formula. Our basic postulate is that as far as the SE is the principle of chemistry, its solutions for chemistry should have the structure that can be related to the chemical formulas. So, in this paper, we first formulate a theory that designs the wave function to reflect the structure of the chemical formula. We call this theory chemical formula theory (CFT). In the CFT, we place the valence ground and excited states of each atom at each position of the chemical formula of the molecule and let them interact using their free valences to form the ground and excited states of the molecule. The principle there is the variational principle so that the ground and excited states obtained satisfy the orthogonality and Hamiltonian-orthogonality relations. Then, we formulate the exact FC theory starting from the initial functions produced by the CFT. This FC theory is referred to as free-complement chemical-formula theory (FC-CFT), which is expected to describe efficiently the solution of the SE by the above reason. The FC-CFT wave function is modified from that of CFT. Since this modification is done by the exact SE, its analysis may give some insights to chemists that assist their chemistry. Thus, this theory would be not only exact but also conceptually useful. Furthermore, the intermediate theory between CFT and FC-CFT would also be useful. There, we use only integratable functions and apply the variational principle so that we refer to this theory as FC-CFT-variational (FC-CFT-V). It is an advanced theory of CFT. Since the variational method is straightforward and powerful, we can do extensive chemical studies in a reasonable accuracy. After finishing such studies, if we still need an exact level of solutions, we add the remaining functions of the FC-CFT and perform the exact calculations. Furthermore, when we deal with large and even giant molecules, the inter-exchange (iExg) theory for the antisymmetry rule introduced previously leads to a large simplification. There, the inter-exchanges between distant electron pairs fade away so that only Coulombic interactions survive. Further in giant systems, even an electrostatic description becomes possible. Then, the FC-CFT for exactly solving the SE would behave essentially to order N for large and giant molecular systems, though the pre-factor should be very large and must be minimized.

Analysis of oxidation decomposition reaction scheme and its kinetics of delafossite-type oxide CuLaO2 by thermogravimetry and high-temperature X-ray diffraction

The oxidation decomposition reaction and its reaction kinetics of delafossite-type oxide CuLaO2, which is a mother phase of new luminescent material, at various temperatures were investigated by thermogravimetry and high-temperature X-ray diffraction. It was clarified that CuLaO2 is not thermodynamically stable in air and reacts with O2, which is represented as the chemical reaction formula, 4CuLaO2 + O2 → 2CuLa2O4 + 2CuO, above 500 °C. It was also revealed that CuLaO2 transforms to a metastable CuLaO2.66 phase with a copper valence of 2.32+ and some phases with lower crystallinity below 500 °C. At 800 °C, a metastable defect perovskite Cu2La2O5 phase was generated at initial period of the decomposition, resulting in variation to mixture of CuLa2O4 and CuO as reaction proceeded. It was found that a first-order reaction model can be applied to the reaction kinetics of the oxidation decomposition reaction. The activation energy for the reaction was estimated to be 65 kJ mol−1 under air flow. It was concluded that CuLaO2 has lower kinetic stability than the other delafossite-type oxides such as CuAlO2 and CuGaO2.

Relations between harmonic frequencies of diatomic molecules

The relations between the harmonic frequencies of different molecules are revealed with the aid of the spring constants of atoms in molecules. Using the atomic spring constants in the related molecules, the force constants for a new molecule can be estimated. The simplest scheme to obtain the force constant of a given molecule is similar to a simple chemical reaction formula, such as A(2) + B(2) → AB, and the corresponding relation between the molecular force constants is k(AB)(-1) = (2k(A(2)))(-1) + (2k(B(2)))(-1). For a given molecule, one can design numerous schemes to obtain its force constant from the atomic spring constants in other molecules. A high degree of periodical regularity appears in the application of different kinds of schemes to the ground states. The reliable schemes for the ground electronic states can be adopted for the excited states. Over two hundred molecules with experimental data available for comparison have been tested. The discrepancies between the calculated and the experimental harmonic frequencies can reach 1% and better; the results show that the present approach is simple in theory and handy to use. The harmonic frequencies for dozens of hetero-nuclear molecules of the transition-metal elements are also predicted.

Study on Durability of Cement Soil under Brine Erosion

In the coastal areas, deep mixing method or high pressure jet grouting method are usually used to form cement soil during the ground treatment. It’s easy to inflict corrosion damage of cement soil when the underground confined water is connected to the brine. Therefore, research of the cement soil’s durability under the brine erosion is of important significance to engineering. Start from the theory of chemical dynamics and damage mechanics, based on the chemical reaction formula between MgCl2 and the cement soil, with appropriate assumption, the relationship between ion concentration and corrosion time is deduced: (C1/C2)β=t2/t1, that is: when the soil eroded to equivalent mechanic effect, the relationship of corrosion time can be obtained in the solution with high and low concentration. Based on stress strain relationship, incorporate chemical damage factor into compression modulus, suggest certain assumptions, the same relationship between corrosion time and ion concentration is deduced.

Study on Durability of Cement Soil under Brine Erosion

In the coastal areas, deep mixing method or high pressure jet grouting method are usually used to form cement soil during the ground treatment. It’s easy to inflict corrosion damage of cement soil when the underground confined water is connected to the brine. Therefore, research of the cement soil’s durability under the brine erosion is of important significance to engineering. Start from the theory of chemical dynamics and damage mechanics, based on the chemical reaction formula between MgCl2 and the cement soil, with appropriate assumption, the relationship between ion concentration and corrosion time is deduced: (C1/C2)β=t2/t1, that is: when the soil eroded to equivalent mechanic effect, the relationship of corrosion time can be obtained in the solution with high and low concentration. Based on stress strain relationship, incorporate chemical damage factor into compression modulus, suggest certain assumptions, the same relationship between corrosion time and ion concentration is deduced.

Failure analysis and redesign of the evaporator tubing in a Kimchi refrigerator

Abstract A failure analysis was conducted on a pitted aluminum tubes in the evaporator used to cool, a Kimchi refrigerator. The root cause of the failure was a pitting corrosion which was traced to chlorine in a cotton adhesive tape used on the tubes. To reproduce the failure modes and mechanisms causing the tube pitting corrosions, a tailored set of accelerated life tests was applied to the evaporator tubing. Using chemical loads, the key noise parameters in the assembly, including a variety of chemical reaction formula, were analyzed. The failure modes and mechanisms found experimentally were identical to those of the failed sample. To correct the problem, the cotton tape in the cooling evaporator was replaced by a generic transparent tape. The B 1 life of the new design is now guaranteed to be over 10 years with a yearly failure rate of 0.1%.

Void Formation Mechanism of Flip Chip in Package Using No-Flow Underfill

This paper investigates the void formation mechanism induced by chemical interaction between eutectic solder (Sn63/Pb37) wetting and no-flow underfill material curing during flip chip in package assembly. During the process, low weight molecular components, such as fluxing agents and water molecules, could be induced by the chemical interaction between solder wetting and underfill curing when these components are heated to melt and cure, respectively. The low weight molecular components become volatile with exposure to temperatures above their boiling points; this was found to be the main source of the extensively formed underfill voiding. This mechanism of chemically and thermally induced voids was explained using void formation study, differential scanning calorimetry thermogram comparison, and gas chromatography and mass spectroscopy chemical composition identification on the suggested chemical reaction formula. This finding can enhance understanding of the mechanism that drives no-flow underfill voiding and can develop a void-free flip chip assembly process using no-flow underfill material for cost effective and high performance electronics packaging applications. Furthermore, this study provides the design guideline to develop an advanced no-flow underfill having high performance at high temperature range for the lead-free application.

Highly sensitive detection method of dibenzyl disulfide and the elucidation of the mechanism

Highly sensitive detection method of dibenzyl disulfide (DBDS) in insulation oil was realized using solid phase extraction (SPE) with active alumina adsorbent followed by gas chromatography equipped with a mass spectrometry (GC-MS). The detection limit of DBDS is around 0.1 ppm. This method is also useful for detecting bibenzyl (BiBZ) and dibenzyl sulfide (DBS). The good relationship between the weight change of copper strip and BiBZ /DBS formation was obtained under heating with insulating oil containing DBDS and copper strip, so it was clarified that BiBZ and DBS are the byproducts of the copper sulfide generation with the chemical reaction between DBDS and copper. The chemical reaction formula between DBDS and copper was proposed based on the assumption that copper sulfide should be generated via Cu-DBDS complex. The temperature dependence of the weight change of copper strip before and after the heating in the insulating oil containing DBDS was quantitatively explained with the chemical reaction formula.

2122 接触帯電による静電付着エネルギーを利用したセルフアセンブルとアセンブルプロセスのモデリング(要旨講演,一般セッション:マイクロナノメカトロニクス)

Novel self-assembly process using electrostatic adhesion energy induced by contact electrification phenomenon was proposed and its analytical formulation was performed for the first time. The contact electrification, which is observed when two different metals, such as platinum (Pt) - Silver (Ag) are contacted, was utilized to align a face of a component on a substrate. First, two types of 1 mm square silicon components with thickness of 0.5 mm coated with Pt or Ag and R substrate were prepared. Adhesion energies for two different metal pairs (Pt-Ag and Pt-Pt) were measured by measuring the vibration energy to separate the components from the vibrating substrate. The experimental results indicated the adhesion energy between Pt-Pt was 0.57 nJ, and Pt-Ag was 1.4 nJ on an average. Next, the face alignment experiment was carried out by vibrating the substrate on which 20 components with thickness of 0.2 mm were placed. The front and back face of the components were coated with R and Ag, respectively and they were split into half of R face up and the other half of Ag face up. We could get 83 % components were aligned as R face up. Finally, modeling of the proposed self-assembly process was performed based on the concept of chemical reaction formula. The forward and reverse reaction rates of the face alignment process were determined by fitting the foumula to the experimental data.

A Study of Calcium Phosphate Crystal Phases Prepared from Oyster Shells

Calcium phosphate was prepared by chemical reaction formula using Oyster shells and <TEX>$H_3$</TEX><TEX>$PO_4$</TEX>solutions. After added to 0.1 M∼0.9<TEX>$ M H_3$</TEX><TEX>$PO_4$</TEX> solution for oyster shell, prepared powders were investigated for heating properties and formation phase with heat treatment temperatures. As the results of XRD analysis of heated powders at <TEX>$500^{\circ}C$</TEX>∼<TEX>$1200^{\circ}C$</TEX>,<TEX>$ CaCO_3$</TEX> phases were observed at the temperature of below 900 TEX>$^{\circ}C$</TEX> and in the condition of 0.1 M∼0.9 M <TEX>$H_3$</TEX><TEX>$PO_4$</TEX> solutions. However, <TEX>$CaCO_3$</TEX>, <TEX>$CaPO_3$</TEX>(OH) and <TEX>$Ca_3$</TEX>(<TEX>$PO_4$</TEX>)<TEX>$_2$</TEX> phases were appeared at the temperature range between <TEX>$500∼900^{\circ}C$</TEX> and in the solution of 0.7 M to 0.9 M <TEX>$H_3$</TEX><TEX>$PO_4$</TEX>. <TEX>$Ca_{ 5}$</TEX>(<TEX>$PO_4$</TEX>)<TEX>$_3$</TEX>(OH) and CaO phases due to the decarbonation of oyster shells(<TEX>$CaCO_3$</TEX>) were appeared at above <TEX>$1000^{\circ}C$</TEX> and in the solution of below 0.5 M <TEX>$H_3$</TEX>X<TEX>$PO_4$</TEX>. However in the case of above 0.7 M <TEX>$H_3$</TEX><TEX>$H_4$</TEX> solutions, <TEX>$Ca_{5}$</TEX> (<TEX>$PO_4$</TEX>)<TEX>$_3$</TEX>(OH) was decomposed into <TEX>$Ca_3$</TEX>(<TEX>$PO_4$</TEX>)<TEX>$_2$</TEX> at more higher 100<TEX>$0^{\circ}C$</TEX>. Thus <TEX>$Ca_3$</TEX>(X<TEX>$Ca_4$</TEX>)<TEX>$_2$</TEX> phases were appeared at higher than 100<TEX>$0^{\circ}C$</TEX>.

Expres: An expert system for synthesizing chemical reaction cycles

An expert system, EXPRES (EXPert system for chemical REaction cycles Synthesis), is developed. This expert system can generate two kinds of reaction cycles systematically, i.e. chemical reaction cycles and chemical reaction clusters, with the help of reaction databases and various kinds of knowledge bases. In the reaction data base, known reactions that have already been proven to proceed at reasonable rates are collected. EXPRES has distinctive features such as reaction rules abstracted and evaluated by experts, learning effect and hierarchically structured knowledge base on effective processing and maintenance. The method for conversion of a chemical reaction formula into a list expession in LISP language is also established. EXPRES can be applied to: (1) derive multistep reaction clusters from a single reaction that is difficult to proceed under industrial conditions; or (2) to find chemical heat pump cycles that work within desired temperature range, for effective use of resources or thermal energy.

THE OXIDIZING PROCESS OF Fe3O4 ULTRAFINE PARTICLES

The conversion of magnetite to maghemite has been studied by M?ssbauer effect. That is a nucleation and growth process of γ-Fe2O3. The change of the concentration of Fe3O4 with time was determined by the change of magnetic moment in the oxidizing process. The chemical reaction formula, -dC/dt = mC3, is only appropriate for the starting stage of the oxidizing process.

The temperature dependence of mortality rate in starved yeast cells.

The thermal inactivation of stable and unstable (persistent lethal sectoring) lines of yeast was investigated at various temperatures. The temperature dependence of mortality rate was adequately described by the first-order chemical reaction formula. A semilog plot of temperature vs. life time of the stable line appeared as a straight line. On the other hand, that of the unstable line had two components: one had the same activation energy as the stable line and the other one had a different lower value. This new component may have originated in a mutated protein and caused the instability.